BUILDING ZONES & LINES FROM SEGMENTS
FORMAT OF POLYGON GEOGRAPHIC FILES
OzGIS is a software system for displaying geographically referenced data as coloured maps on graphics display devices. The maps portray the data values associated with geographic zones by uniform colours, site data by different sized symbols, and line data by different line types.
The system can be used to analyze socio-economic and demographic data produced by censuses and surveys and to support management decisions associated with for example marketing, sales, site and personnel location, and advertising. Other spatial data such as environmental data can be displayed.
OzGIS aims to accept basic data files and to provide most of the facilities required for the analysis and display of attribute data as maps. The analyst has to be able to rapidly use the facilities, so OzGIS provides an interactive user interface. The user interacts via menus and is aided by on-line assistance.
Visual inspection of choropleth maps is the intuitive way to interpret the spatial features of data. An analyst needs to be able to rapidly display and manipulate maps to aid his understanding. OzGIS was designed to enable maps to be changed within seconds so the analyst does not lose his train of thought. OzGIS enables the analyst not just to display a map, but to generate the map that best shows the features of the attribute data. A hardcopy map can be generated as the final operation as a record or for dissemination.
Easy to use systems are either trivial systems, or have a small number of options. The enormous number of options within OzGIS means that it takes some time to understand everything. However, maps can be produced quite simply by using only a small number of options and by using the system defaults.
OzGIS can be considered as one system of a facility for analysis and display of Census type data. The various components are:
Hence you may use:
It is expected that an analyst would have access to a PC close
to his office. The PC/workstation may be connected via a computer
network to provide access to large host machines. The host machines
would contain the database systems from which map data could be
extracted, and other systems for analysis and hard-copy generation.
This manual is supplied on disk as C:\OZGIS.HTM and can be viewed
by opening it as a file within a web browser.
The software was originally developed as part of a research project at the Division of computing Research of the Commonwealth Scientific and Research Organisation (CSIRO) in Canberra for a mapping product called COLOURMAP.
Software development started in 1979 with the purchase of hardware that had been developed for the DIDS mapping system in the White House in Washington DC. This hardware consisted of a PDP11 mini-computer and a DeAnza display system. The display featured a 12bit frame buffer, 4096 value primary look-up table and cascaded 256 value colour table. This enabled maps of up to 4000 zones (e.g. USA Counties) to be displayed and manipulated very rapidly, and is the best hardware so far produced.
The environment changed over several years, with moves to larger PDP11 systems and to VAX and CDC machines. Several display systems were used, Tektronix, Jupiter and RAMTEK, and maps were generated on plotters and film recorders. The system was also available on CSIRONET, an Australia-wide computer network with Control Data and FACOM host computers. The 1981 ABS Census data could be accessed via the SIR/CENSYS system on the Cyber 845. A system was developed to handle the Census district boundaries digitised by the Division of National Mapping, to enable windowing, line simplification and aggregation for production of geographic map data files. The SAS system was available on the FACOM 180 for statistical analysis and display of map data.
The first year of development was supported by Techway, and APASCO supported the development of techniques for retail applications. APASCO used the system and hardware for several years as part of their consulting activities to churn out thousands of maps.
The Division of computing research was split into the CSIRONET computing bureau and the new Division of Information Technology in 1985. Later, CSIRONET was given to private industry. The mapping project was abandoned. The software was resurrected in late 1990 and ported to the IBM PC to produce a system for DOS. A WINDOWS 3.1 version came later. The current WIN95 / NT version was released early in 1998.
The purpose of the Guide is to introduce the facilities of OzGIS. The Guide is intended to complement the messages and assistance given during the operation of OzGIS. The user should understand the techniques of statistical data analysis and computer mapping, and also have an elementary understanding of colour representations.
OzGIS is developed by The Clever Company, a Canberra based software company offering consulting and contract programming services in the areas of:
Digital map data can be purchased from many Government and private companies. Demographic data are available from various Census Bureaux.
Free / demonstration data are also available.
Most major suppliers have a site on the Web these days, so use
a search engine to look for obvious words such as GIS, map etc.
As is usual, once you get to a major site there are lots of links
to other places.
You can start at the Australian Bureau of Statistics' site www.abs.gov.au, which has links to other Census bureaux
www.clark.net/pub/lschank/wed/census.html has lots of links
to other data
The USGS is the major site in the USA usgs.gov.au
AUSLIG is a major site in Australia. It has some free data. www.auslig.gov.au
The installation of the OzGIS system is described in the file
\OZGIS\READ.ME
OzGIS expects whatever is a fairly standard PC. Currently this
is:
Earlier versions were written to run on machines with limited
memory and made heavey use of disk IO. The 32-bit version is moving
towards using RAM to speed up data manipulation and display, so
processing of large files may require 32meg of RAM, or more.
The file \OZGIS\OZGIS.INI is the initialisation file for the system.
The file should NOT have to be modified initially.
The file should be well commented, and modifications should be fairly obvious.
Ensure that you dont alter the columns used i.e. the file is not free format!
The first three lines should define you video board (although the system currently gets the information from the WINDOWS screen driver).
e.g. for the VGA board
640 Number of pixels across VGA screen
480 Number of lines on screen
16 Number of colours
The initial user interface settings for trace and help levels are here. You can modify them later if you like.
An important part of the file is the entries that define the fonts that are used. There is more information about these in the section on the formats of device files.
The first font in the list is usually used (set to Arial initially).
You can view the fonts on your system by choosing the Fonts icon in the Control Panel window.
If you find that no text is displayed on maps you probably do not have the usual fonts installed so will have to change to one that you have.
Fonts have to be variable size so TrueType fonts should be used.
OzGIS uses the standard WINDOWS printer for output of hardcopy maps.
Windows print drivers are also used for other devices e.g. plotters,
special file formats.
Use the Sounds icon in the Control panel to enable / disable bleeping
when dialog boxes appear.
Typing alt+PrintScreen will load a displayed map into the clipboard
from whence it can be used by other packages e.g. inserted into
a Word document.
Most data are entered into OzGIS as external data files. Examples are Census data and Census digitised boundaries. These files come from Census Bureaux, Mapping agencies, data supply companies or your own data-base systems. Some data can be prepared or modified with word processors or spreadsheets.
Several data fornmats are supported. If your format is not supported you have to convert it into one of the supported formats or the OzGIS standard format for the type of file. The data entry options are initiated by choosing IMPORT from the menu.
The main menu enables selection of the type of file:
IMPORT GEOGRAPHIC FILES
IMPORT ATTRIBUTE FILES
IMPORT A NAMES FILE
IMPORT A COMBINE FILE
IMPORT A DEVICE FILE
Choosing a menu item may generate another menu e.g. for GEOGRAPHIC FILES
IMPORT A STANDARD FORMAT GEOGRAPHIC FILE
IMPORT NEW FORMAT SAS GEOGRAPHIC FILE
IMPORT OLD FORMAT SAS GEOGRAPHIC FILE
IMPORT A DLG-3 OPTIONAL FORMAT GEOGRAPHIC FILE
IMPORT A GINA FORMAT GEOGRAPHIC FILE
IMPORT A TIGER FORMAT GEOGRAPHIC FILE
IMPORT A DIME FORMAT GEOGRAPHIC FILE
IMPORT A DXF FORMAT GEOGRAPHIC FILE
.
.
.
.
where DLG-3, TIGER, DXF etc are different data formats.
In all cases, data entry requires giving the name of your data file and supplying the name to be used for the internal file. Data files usually have names that finish with the extension DAT. e.g. LONDON.DAT, A:SALES.DAT.
The one time a full file name can be given within OzGIS is when reading a data file, as it is sometimes inconvenient to rename files . For example you may have TIGER files from the US Census bureau on CD-ROM. Then you could read the files directly by giving the complete file name e.g. E:/18/003/TGR18003.F42
Often data files will need further processing before used for mapping e.g. attribute data may need manipulating by arithmetic expressions or geographic line segments may need thinning and forming into polygons.
Future versions of the OzGIS system may have incompatible internal file formats so always keep important data files.
The system comes with many of the system files already entered
e.g. device files. The data files are also provided.
The OzGIS system is supplied with a complete set of sample external data files so that the user can become familiar with the system. These files can be inspected to clarify the file formats.
The files are usually in the directory \OZDATA and have names
DEM*.*
Generally there will be two data files for each map; a file that describes the map boundaries and another for attribute data. The example files are:
1. Far East Asia
Attribute file - FEA-A
Geographic file- FEA-G
2. Lowe electorate (Sydney)
Attribute files- LOWE-A1 and LOWE-A2
Geographic files- LOWE-G (zones), LOWE-S1, LOWE-S2 (sites)
These files are already entered (supplied with the system).
3. Australia
Attribute file - OZ-A
Geographic file- OZ-G
These files have already been input in the demonstration chapter.
4. Washington DC Census Tract/BNA and TIGER lines
These have been entered off CD-ROM files and preprocessed ready for display.
attribute file WASHTRACT
Geographic zones file WASHTRACT
Geographic lines file WASHROADS
Geographic lines file WASHRAIL
5. Africa in Atlas format
Geographic data files AFRICA.DAT
6. Hawaii in DLG-3 optional format
These came off a USGS CD-ROM
HAWDLGWB.DAT Water boundaries (islands)
HAWDLGAB.DAT administration boundaries
HAWDLGST.DAT streams
HAWDLGRD.DAT roads
7. DXF example files from VIC Roads. These have extensions *.DXF
8. London Cholera
Files are supplied for the classic mapping example where the mapping of the houses where people died during the 1854 outbreak of Cholera onto a street map of inner London, and then mapping the water supply, showed clustering about one pump. The data files are in IDRISI format.
STREET.* London streets (lines)
DEATH.* Where fatalities occurred (points)
PUMP.* Locations of water outlets
9. ACT / Canberra
Test data are provided for Canberra.
CANBP1.DAT and CANBP2.DAT are shopping centre locations
ACTSHOP.DAT is sample attribute data for shopping centres
L81SEG.DAT are 1981 Census boundaries for the ACT. This file is Crown Copyright of AUSLIG, Australia's national mapping agency. It is supplied with the permission of the General Manager, Australian Surveying and Land Information Group, Dept Arts and Admin. Services, Canberra, ACT.
L81ATTR.DAT is sample attribute data for the above (mangled Census dervived data). L81.ATT is the entered data.
ACTSUBURB.DAT is a points file of names of Canberra suburbs (LGAs).
ACTSUBUR.GEO is the enetered geographic file.
ACTMT.DAT is point data for ACT mountains.
Two files for site catchment examples are:
CATCH.CAT example site catchments and
CANBL81.GEO a geographic file for Canberra city.
10. D.C.W.
The Digital Chart of the World is an extensive vector database supplied on 4 CD-ROMs at minimal cost.
The test data are from the low resolution browse database. The files are:
DCWLAND - World polygons (PO lines data param file modifed to give lines
131, 132 feature code 99 - these close asia at the edges)
DCWPOTXT - polititical names
DCWPPPNT - pop places locations
DCWPPTXT - pop places names
DCWDNLN - drainage lines
Feature codes:
DCWLAND - none
DCWPOTXT - 1=land place names, 2=ocean place names
6=mountains, 8=islands, 10=deserts
DCWPPPNT - none
DCWPPTXT - none
DCWDNLN - 1 = rivers, 2=inland shorelines
The characteristics of devices and the appearance of maps are given by display files. Data files are provided for all the device files supplied with the system.
The files are already entered on the system and are described
in a later chapter.
You choose processing and display options from pulldown menus
or from a pop-up menu that appears in the OzGIS window. The menu
changes depending on what you are doing.
You will find that some there are lots of menus, and it is difficult at first to know where you are in the menu "tree". To make it more confusing the menus are dynamic e.g. adding something to a map can cause a new menu item to appear that allows you to delete that item.
The general approach is: if the current menu does not have the option you want select from the pulldown menu. You will find that you cannot return to a previous menu at some "main" menus. This prevents loss of map data at various stages; Select "Top menu" from the Control menu.
Main menus appear as pulldown menus.
Questions are asked by OzGIS when data are required for an operation. The user must supply the data by entering appropriate responses in a dialog box. The format of questions consists of the question, a possible range of values in brackets (if appropriate), a default value in parentheses (if appropriate) and terminated by a question mark. The range of values and default values indicate the form of the expected answer. An example is a request to replace an existing file:
DO YOU WANT TO REPLACE THE FILE [Y,N]?
The user must respond by clicking on YES or NO.
Commands are issued by OzGIS when an operation has to be performed by the user. When the operation is completed, control returns to the appropriate menu.
The format for commands consists of a directive, a possible range of values in brackets (if appropriate), a default value in the input field (if appropriate), terminated by a colon. An example is:
TYPE NUMBER OF CLASSES [1-6] (4):
The number of classes must be in the range 1 to 6, and if the
user simply presses the "Enter" key a default value
of 4 will be selected.
Graphic interaction in OzGIS involves the use of the mouse to control the cursors on the monitor. Use the left mouse button to select.
The user is directed to operate the mouse etc by the appearance of the cursor on the monitor and by an appropriate command on the screen. The extent of the command depends on the current level of user communication
There are several types of cursors:
Every program generates printout on a file OZGIS.OUT. This includes:
Every time a map is interactively queried the list of map items
retrieved is output to a file QUERY.OUT
Error messages are also output to a file WINDOWS.OUT
The following kinds of files must be entered into OzGIS:
Data files usually come from Census bureaux, map data suppliers or your corporate database. Data are now available on the net.
External data files must be entered into OzGIS explicitly. This operation permits OzGIS to generate internal representations of the data for efficient processing and to check the data.
Certain files must be prepared explicitly within OzGIS under user direction. These files are:
Some files can be prepared externally or internally. These are:
Some files are usually prepared with a word-processor. These are:
The file types will become obvious with use of the system. There are many different types of files used:
OzGIS distinguishes the various types of files, so you can give the same name to files of different types e.g. you may have a geographic file called AFRICA and also a (probably related) attribute file called AFRICA and you may save the map using these files in a saved display file also called AFRICA.
The system differentiates between files by adding an extension to the given file name e.g. the AFRICA attribute file would actually be AFRICA.ATT
You generally dont have to worry too much about extensions, but they are:
It is essential to understand the data held in geographic files
before the more advanved features of OzGIS can be used.
A geographic file can contain some of:
For simple mapping of, for example Census data, the fast display polygons are all that are required.
However, OzGIS uses a topological structure for zones and lines which allows manipulation of the geographic data for operations such as:
A complete zones geographic file can be constructed from line segments. See the building process. Such a file contains:
Fast display polygons, which are ordered so base polygons are
displayed first, followed by islands within them, and so on.
Device files control the appearance of maps:
Experience showed that it is better to have fixed sets of definitions rather than allow the user to specify the display parameters.
There are sets of device files available:
The supplied files have a naming system e.g.
The best way to understand device files is to look at the contents, for example:
Select Data-> CHANGE DEVICE FILE
Select C256SV5 .DEV
Select Data-> DISPLAY DEVICE CHARACTERISTICS
You will now get a display that shows the text types (sizes and colours), lines (types and colours) and the various polygon fills as rectangles. Of particular interest are the class colours. The bottom set is a sequence of 121 colours which is designed to give the appearance of increasing attribute values. All the colours will be different (and can be used for "continuous colour" maps). The set of colours above are a 7 x 7 set for bivariate maps. They actually map onto the same set as for single variate maps, so if bivariate maps are to be produced different device files should be used.
Now choose a bivariate device file B256BV2 .DEV and display that.
The bivariate sequence will show a progression of colour in each
dimension.
It is usual to use a black background when displaying maps on
the screen as white seems to "wash out" the colours.
However, if you want to print maps you will need a white background
e.g. device file C256SV1.
You should now display a few of the single variate device files (C256SV?) and decide on one that you will use as the default device file.
When you have decided on the default file type exit from OzGIS and:
cd \ozgis
copy C256SV6.DEV DEFAULT.DEV (using the file you have chosen)
This will overwrite the device file that was supplied as the default
with the system. Obviously you can select a different device file
for display at any time, and you should do so for bivariate maps.
The colour sequences are designed to provide a colour progression that can help interpret the pregression in values in the attribute data.
The sequences were generated by sampling at equal intervals along
curves through uniform colour space, and then transforming the
values using a model for the colour response of colour / TV monitors.
There are several types of displays:
These maps display data from both attribute and geographic files. There are one or two streams of attribute processing for the types of
maps available for zone, line and site attribute data:
The type of map is selected before display and cannot be changed except by returning to the main menu.
Site data can be displayed in several ways:
Line data can be displayed in several ways:
These maps display data from geographics files (without any attribute
data. example
When you have prepared a map and have it displayed you can use the File->Save to store all information
about the map in a file.
File->Open can be used to restore a map display..
This option was not ported from the PDP11 / DeANZA version
but may be partially re-implemented.
Special options are available for the display of time lapse files. The following parameters can be altered:
The zone legend format is not updated during a time lapse sequence,
and by default the class description of the legend is set to the
"HIGH" and "LOW" format. Histograms and scatter
plots cannot be displayed during a time lapse presentation.
Attribute data is held in attribute files. Each file can have
many variables e.g. USA Census data STF1A files can have over
900 variables. This chapter explains the options used to select
which attribute is to be displayed on a map.
Various attribute files can be nominated to generate a map display. Attribute may be selected for quantisation and display from attribute files in various ways:
To try these options, display a zones map using attribute file LOWE1 and geographic file LOWE as before and then select CHANGE ATTRIBUTES.
The menu gives the following options:
SELECT FROM A LIST
DISPLAY THE NEXT SEQUENTIAL ATTRIBUTE
SELECT AN ATTRIBUTE FOR DISPLAY BY NUMBER
SELECT AN ATTRIBUTE FOR DISPLAY BY DESCRIPTION
A list of available attributes is displayed and one is selected
by double clicking with the mouse.
This option will simply select the next attribute off the file.
A particular attribute may be selected by the position within
the file. Type zero to generate a list of the attributes on the
current file.
The attribute can also be selected by typing part of the description
e.g. "FORC" to retrieve "ARMED FORCES". Typing
L lists the attributes.
This option enables a new attribute to be generated for display
e.g. the expression " #2 + #4 " forms a new attribute that is the sum of the second and fourth attributes on the input file.
Attributes can also be prepared as a data preparation option and
the options are fully described in the relevant chapter.
It is your responsibility to ensure that the names referenced by the attributes match the names of the displayed zones, lines or sites in the map. Obviously colours can be assigned only to the zone with names common to the attribute and zone files etc.
Only some of the names have to agree; it is quite common to process
attribute data for a larger area than is displayed.
Quantisation is the process of assigning map items to classes according to their attribute values.
The quantisation process is the most important aid for the analyst in understanding the features of the attribute data. The quantisation method and parameters should be chosen logically according to the purpose of analysing the data.
The aim is to display the map that best shows the spatial features
and distribution of the data.
Attributes are usually presented to OzGIS as values which have to be quantized into a number of classes for display.
A maximum of 10 classes can appear in single variate zone displays and 9 classes (a maximum of 3 per variate) in a bivariate display. A maximum of 4 classes is available for lines and 4 classes for sites.
The best maps usually have a small number of classes; manipulate the map to show the data according to requirements. This contrasts with the production of atlases, where large numbers of colours are used as the purpose to which the map will be put is not known.
To try these options, display a zones map using attribute file LOWE1 and geographic file LOWE as before, and select DEFINE QUANTISATION.
The quantisation menu has the following form:
CHANGE THE QUANTISATION METHOD
CHANGE THE NUMBER OF CLASSES
SELECT THE ZONES FOR QUANTISATION
SELECT THE ATTRIBUTE VALUE RANGE FOR QUANTISATION
You will find that this menu is dynamic as usual. You will find other entries such as SELECT THE LINES FOR QUANTISATION or CHANGE THE NUMBER OF SITE CLASSES for different types of maps.
Try changing the number of classes first and then work through the various methods.
There are other options to change the list of zones to which quantisation
is applied and to change the range of values over which the method
operates.
Selecting the menu option CHANGE THE QUANTISATION METHOD will display a new menu of the form:
USE EQUAL VALUE INTERVALS
USE QUANTILES
USE SELECTED CLASS INTERVALS
USE SELECTED NUMBER OF ZONES PER CLASS
USE REFINED EQUAL VALUE INTERVALS
USE THE MEAN AND STD DEVIATION METHOD
USE THE NESTED MEANS METHOD
USE THE NATURAL BREAKS METHOD
USE SELECTED PERCENTILES
USE SELECTED CLASS RANGE PERCENTILES
USE INTERACTIVE SELECTION OF CLASS INTERVALS
USE EQUIVALENCE CLASSES
USE CURRENT CLASS RANGES
USE CURRENT NO PER CLASS
USE PSEUDO CONTINUOUS-COLOUR
You should try out these various methods e.g. with the attribute and geographic files OZ.
The following methods for quantization are available for determining the class intervals:
The range of values over which the quantization is applied can be restricted in all methods. The following options are available for limiting the range:
Zones with values outside these limits are assigned the "excluded zone" value and colour, lines and sites are not displayed.
The menu is of the form:
QUANTISE FOR ATTRIBUTE VALUE RANGE
TYPE IN ATTRIBUTE VALUE LIMITS FOR EVERY QUANTISATION
FIX LIMITS AT CURRENT VALUES
QUANTISE FOR AUTOMATICALLY SELECTED VALUE LIMITS
For example a standard legend for percentage data with value ranges
0,25,50,75 and 100 could be generated by choosing extremes to
be 0 and 100 and fixing them, and by using 4 equal value classes.
Each of the attribute processing streams has an associated list that holds the names of the items being quantised i.e. zones or lines or sites. There is one list for a single stream, one zones list for bivariate maps, and for two streams there is a list of zones and a list of lines or sites.
Each list selects the items that are to be quantised from the corresponding attribute file. When a map is generated the lists are set to all the names if the attribute files (common names in the case of bivariate maps).
Zone lists can be reset to:
The menu is of the form:
QUANTISE FOR DISPLAYED SITES
QUANTISE FOR ALL SITES IN THE ATTRIBUTE FIL
QUANTISE FOR SITES IN A NAME FILE
EDIT SITES USED FOR QUANTISATION
Zone lists can also be modified by adding or deleting zone names by typing in a name or selecting the zone with the cursor
Site lists and line lists can be modified by giving the names.
Hence the quantisation can take place for a set of items that is independent of the displayed, zone lines and sites (although it is illogical for none to be the same). It is common for the quantisation to be carried out over a larger geographic area than that being displayed.
Sometimes zones are removed because the attribute data are doubtful e.g.
Geographic files can be displayed on zones, sites and lines maps to add extra information, usually for "navigation" purposes.
Overlays are selected by choosing DEFINE GEOGRAPHIC OVERLAYS off the main map display menu.
A menu appears of the following form:
OVERLAY LINE SEGMENTS FROM A GEOGRAPHIC FILE
OVERLAY MARKERS FOR SITES IN GEOGRAPHIC FILE
OVERLAY NAMES FOR SITES IN GEOGRAPHIC FILE
UNDERLAY POLYGONS FROM GEOGRAPHIC FILE
OVERLAY LINE SEGMENTS FOR FEATURE CODES
OVERLAY MARKERS FOR SITES FOR FEATURE CODES
OVERLAY NAMES FOR SITES FOR FEATURE CODES
UNDERLAY POLYGONS FOR FEATURE CODES
This menu is similar to the one used with geographic (no attributes) maps.
Polygons can be displayed underneath, such as postal districts under a sites map.
Lines are often displayed on top of a map e.g. roads, rivers.
Points can be displayed as symbols e.g. locations of shopping centres.
Point labels can also be displayed e.g. names of towns.
Overlays etc are displayed in the order polygon underlays, then the standard map according to attribute values, then line overlays, then point symbols, and finally names.
Within each type of overlay display takes place in the order the overlays are defined. In some cases order of definition is important as a later overlay can obscure an earlier one.
The basic geographic files contain polygons,lines, points and
names. e.g. a file of one level of census boundaries (e.g. blocks)
could be displayed as a lines overlay. Files built with BUILD
TOPOLOGY also contain approximate centroids of zones with labels
being the zone names.
A series of options are available to control the general appearance of maps. These are chosen by selecting CHANGE DISPLAY FEATURES from the main map menu.
The menu is of the form:
DISPLAY TEXT
DEFINE ATTRIBUTE DIAGRAMS ON MAP
ADD STATISTICS TO DIAGRAM
CHANGE ZONES LEGEND
CHANGE LINES LEGEND
CHANGE SITES LEGEND
CHANGE GEOGRAPHIC OVERLAYS (GIS) LEGEND
DISPLAY SYMBOL LEGEND
DISPLAY REGION GRIDS
The actual options that appear depends on the type of map. The
options are described in the following sections:
A legend is always displayed on the monitor when an attribute is quantised for map display. Similar legends are displayed for zones, lines and sites.
The menu to change legends has the form:
REMOVE/INCLUDE CLASS RANGES
ANNOTATE CLASS BOXES WITH 'HIGH' AND 'LOW'
TYPE IN CLASS ANNOTATION (2 LINES PER CLASS)
CHANGE ANNOTATION FOR A CLASS
TYPE IN CLASS ANNOTATION HEADER
REMOVE/INCLUDE CLASS ANNOTATION HEADER
REMOVE/INCLUDE NO. ZONES IN CLASSES
REMOVE/INCLUDE MISSING DATA BOX
REMOVE/INCLUDE EXCLUDED ZONES BOX
REMOVE/INCLUDE UNITS DESCRIPTION
TYPE IN ZONES LEGEND TITLE
REMOVE/INCLUDE ZONES LEGEND TITLE
SPECIFY CLASS RANGE DISPLAY PRECISION
SELECT ZONES LEGEND VIEWPORT WITH THE BOX-CURSORS
The elements of a legend are:
Zone legends have fixed size boxes that give the colours used for the classes.
Site legends have variable sized symbols in a special colour that give the markers and their sizes used for the classes.
Line legends replace the boxes by sample lines in a special colour that give the line types used for the classes.
All text in a legend is written with small fixed size characters.
Display of the legend elements can be controlled by the user. The boxes corresponding to attribute classes are always displayed but the elements (including "excluded zones" and "missing data " boxes) can be removed.
Some of the legend text can be replaced by characters entered by the user on the keyboard, viz.,
The default map layout sets the map image viewport as the left three quarters (approximately) of the monitor, and the legend viewpoints on the right side of the screen. The zone legend is on the bottom, line or site legend above.
New legend viewpoints can be selected with the box cursor. A single
variate legend may need more than one column to fit.
When line overlays, markers, text at points or polygon underlays
are displayed a legend appears that describes the overlays. The
text must be specified by the user.
When several line files are being displayed using different lines, or several site files are displayed using different markers, a legend can be added.
The line and marker legends have similar format:
Lines of text can be typed in and displayed on the screen in one of the four available text types. The text is positioned with the cursor. Up to 20 lines of text can be displayed.
Lines of text can be deleted and moved around the screen.
Text is usually added to a map to supply extra information e.g.
the name of the geographic region and type of zones, organisation
names, disclaimers.
A menu is available to control diagrams added to an attribute map.
Select DEFINE ATTRIBUTE DIAGRAMS ON MAP.
DISPLAY THE SCATTER DIAGRAM
DISPLAY THE ATTRIBUTE DISTRIBUTION
DISPLAY THE QUANTISATION RESULTS
DISPLAY THE SORTED ATTRIBUTE VALUES
REMOVE/DISPLAY AXES
REMOVE DIAGRAM
CHANGE DISPLAY VIEWPORT
(a) Histograms can be displayed in the map area. The histograms show one of the following:
the number of items (zones or sites) within equal intervals of a single attribute
the number of items within class intervals of a single attribute
the attribute values corresponding to zones sorted in ascending order of attribute value.
The bars of a histogram are coloured according to the class colours in the legend. For two variate displays, two histograms can be displayed one underneath the other. The histograms provide an overview of the statistical distribution of the attribute values.
(b) Scatter plots can be displayed in the map area for bivariate zone displays. The plots show the distribution of zones within the ranges of each attribute. The elements of the plot are coloured according to the class colours in the legend. The scatter plots provide an overview of the statistical distribution of the attribute values.
(c) Statistics can be added to the diagrams:
mean and standard deviation lines
median
A regression polynomial of order 1,2 or 3 can be added to a scatter diagram.
The diagram viewport is selected with the cursor.
Addition of a distribution histogram or scatter diagram (bivariate)
add considerably to the information content of a map. They are
displayed by default.
Options to change colours are no longer available. They were removed when DOS limits were exceeded. They may be re-implemented.
All colours within a map display can be changed by the user when a 256 colour VGA display system is being used. Individual colours can be selected in three ways:
Any of these ways can be selected by the user.
The set of colours is assigned to map classes and associated map elements by reference to the current device file. This enables colours for all of the classes to be assigned quickly, although individual colours in the set can be modified subsequently. Displayed elements must be identified in order to change their colour.
Certain elements are explictly referenced in the menus associated with colour change, and can be identified by selecting the appropriate menu option. These elements are:
Specific attribute classes, text, markers and lines are identified
by number.
Map regions enable complex map layouts to be generated. Maps often have only one region, typically zones from one geographic file displayed on the default viewpoint on the monitor. Multiple regions, each with defined window and viewport provide many possibilities:
For example:
These options are for the geographically referenced features of a map. There is a different set of options for defining other features on a map such as text and legends that are simply positioned on the screen.
Definition of map regions is requested by selecting MAP REGIONS from the main map menu after a map has been displayed. A menu then appears of the following form:
CHANGE THE DISPLAYED ITEMS IN THE MAP
CHANGE MAP REGION WINDOW (GEOGRAPHIC AREA)
ZOOM MAP REGION WINDOW ABOUT X-HAIR POINT
CHANGE MAP REGION VIEWPORT (SCREEN AREA)
DEFINE NEW REGION FOR QUANTISED ZONES
DISPLAY MORE QUANTISED ZONES ON A REGION
DELETE QUANTISED ZONES FROM REGION
These few options enable comples layouts to be defined (sometimes
with a lot of playing around). If a map is complex it is recommended
that the map be saved often so you will not have to start from
the beginning if a mistake is made.
A new map region is established when a geographic file is displayed. The region is defined by the geographic window (or subset) and its displayed area (or viewport) on the monitor.
A standard map consists of one region. The window is the whole of the geographic file and the viewport is most of the screen.
Other regions can be added to a map. A maximum of 10 map regions can be defined in a map. The option DEFINE NEW REGION FOR QUANTISED ZONES enables other geographic files to be added to the map, each on their own part of the screen, and to be coloured according to the attribute file values.
For example, you may want to display a map of 5 counties, where you have 5 geographic files (one for each county) and one attribute file that has the values you want to display. You start by displaying just one geographic file and then use this option to add and position the other four files. You will find that it takes some time to finalise the layout in this type of map.
Regions are identified by number, being the order in which the regions are defined. A standard map has only region number one, and you do not have to specify the region number.
A geographic window is initially the total area of the geographic file (Files are subset as a data preparation process). You can change the part of the geographic file that is displayed by selecting a new geographic extent via the options CHANGE MAP REGION WINDOW (GEOGRAPHIC AREA) or ZOOM MAP REGION WINDOW ABOUT X-HAIR POINT
A new viewport is selected by positioning the cursor on the monitor with the mouse or arrows (i.e. it is a rectangular part of the screen) via the option CHANGE MAP REGION VIEWPORT (SCREEN AREA)
Polygon underlays, line, point and name overlays can be added to any map region. This process is the same as already described in the chapter on overlays except that the region number has to be given if there are more than one.
More than one geographic file can be displayed on a region according to the attribute data with DISPLAY MORE QUANTISED ZONES ON A REGION. For example you may want to display maps of two adjoining states. You start by displaying one of the geographic files for the attribute file in the standard way. You then add the second file to the same region (and adjust the viewport and window). The two states will neatly fit together (if the projection & coordinate system is the same).
Geographic files are automatically windowed, scaled and clipped for display on map regions.
When multiple files are displayed on a region, the precedure order is polygons, quantised zones, lines, sites, line overlays, markers and finally text at points.
Multiple regions can be defined anywhere on the map display area of the monitor. However, if regions overlap the display procedure is established by the order of definition. Therefore the user should consider the order of display carefully in multiple region presentations.
Geographic files can be displayed in any order, and regions can be defined and changed as desired.
Many of these operations destroy the data in the display system
memory (the map display is corrupted) so: Select "Display
map" from the Control menu.
A list of displayed items (zones, lines and sites) is maintained by the system.
The list can be changed by selecting CHANGE THE DISPLAYED ITEMS IN THE MAP, which displays a menu of the form:
USE THE ITEMS IN A NAMES FILE
USE ITEMS IN THE CURRENT ATTRIBUTE FILE
USE DISPLAYED ITEMS FROM RANGE OF CLASSES
USE THE ITEMS THAT ARE QUANTISED
EDIT THE DISPLAYED MAP ITEMS
The list is sorted into alphabetical order, and the items are displayed using pixels corresponding to the position in the table . This enables items to be selected with the cursor and identified.
A list of flags corresponding to the map list is also held. The flags enable some of the displayed items to be dropped interactively. The flags are usually set to items in the attribute files:
The options are:
Items can be added or deleted by selecting them with the cursor
or typing the name.
Up to 10 sets of zones files can be displayed on defined regions. Adjacent files will automatically join. GKS clips the polygons to the edges of the region viewports. Where regions overlap, the zones of the last one to be displayed will overwrite the displayed data underneath. Zones that are not in the map list are not displayed.
The zones are displayed every time attribute data are quantised
for the appropriate classes.
Up to 10 sets of lines can be displayed on regions. GKS clips lines to region viewports. Lines that are not in the map list are not displayed.
Each file is assigned to a different line, and is displayed in
that line colour. Four different lines are available. The results
of the quantisation are displayed by using different line types.
The attribute data can be quantised into up to four classes, so
four line types are used. The line files are assigned to the four
available lines according to overall classification when they
are defined (e.g. roads, railway tracks and rivers).
Up to 10 files can be displayed on regions. Sites that are not in the map list or are outside the region window are not displayed. Each file is assigned to a different marker and is displayed in that marker's colour and background colour. Four different markers are available. The results of the quantisation are displayed as different sized markers.
The attribute data can be quantised into up to four classes so
four different marker sizes are used. The files are assigned to
the four available markers according to overall classification
(e.g. owners of banks at the sites).
The segments from up to 10 geographic files can be displayed as
overlays on map regions. Each file is assigned to a region and
one of four available lines and is displayed as a solid line in
that line's colour. GKS clips the lines to the region's viewport.
The polygons from up to 10 geographic files can be displayed as
underlays on map regions. Each file is assigned to a region and
one of eight available polygon colours.
The points from up to 10 geographic files can be used to display
markers at points in regions. Each file is assigned to a region
and to one of four available markers. Markers are not displayed
for points outside the region's window.
The points from up to 10 geographic files can be used to display
names at points in regions. Each site file is assigned to a region
and to one of four available types of text. Names are not displayed
for points outside the region's window.
The window and viewport of a map region can be modified by selecting
a new one with the cursors. Files displayed for quantisation can
be deleted from regions, unless the only one of that type.
Selecting ANALYSE from the main map menu enables further analysis of a displayed map (with attribute data). The following menu appears:
INTERROGATE MAP DATA
GENERATE MAP REPORT ON FILE OZGIS.OUT
DISPLAY ATTRIBUTE STATISTICS
An option is available to write a full map report (giving details
of the displayed items, their attribute values and class numbers)
on the file OZGIS.OUT
The statistics of displayed attributes can be computed and displayed under user control.
The following statistics are computed for a simple attribute:
For pairs of attributes (bi-variate displays) the above statistics are computed for each attribute, as well as
When a map has been displayed, it is possible to interrogate the map data interactively. The actual menu depends on the type of map, but is of the form:
LIST DATA FOR A CLASS RANGE
LIST DATA FOR NAMES TYPED AT TERMINAL
LIST DATA FOR ITEMS IN A NAMES FILE
LIST DISPLAYED SITES
LIST QUANTISATION SITES
LIST SITES WITHIN WINDOW SELECTED WITH BOX-CURSOR
LIST SITES WITHIN DIGITISED POLYGON
LIST SITES WITHIN CIRCLE, TYPED IN RADIUS
LIST SITES WITHIN CIRCLE, CURSOR SELECTED RADIUS
The details generated by interrogation are the names of the zones, lines or sites, the values of the displayed attributes (one value for single variate displays, and two for bivariate) and their assigned class number.
The map can also be interrogated for the textual information held in text attribute files. This enables non-numeric information to be accessed in the same way as the values in standard attribute files.
The options for interrogation are:
(a) class number range - items (zones, lines or sites) within a specified range of class numbers.
(b) single item identification - zone line or site selected by entering its name at the keyboard.
(c) set identification - items selected by a names file, items in map, or items in quantisation lists.
(d) Lists - The names of all the displayed items are held in one list. Each attribute stream has an associated list of items that are being quantised.
(e) Interactive selection
The list of items selected interactively is also output to a file
QUERY.OUT for use either as a names file or for export to other
systems.
The raw data are input to the system using IMPORT DATA FILES. However, the data often need further processing. Also, some data needed within the system cannot be specified as data files and need to be prepared. These facilities are provided by the PREPARE option in the top menu.
The main menu is of the form:
PROCESS ATTRIBUTE FILES
PROCESS GEOGRAPHIC FILES
PROCESS NAMES FILES
OUTPUT EXTERNAL DATA FILES
The PROCESS ATTRIBUTE FILES menu is:
FORM ATTRIBUTES WITH ARITHMETIC EXPRESSIONS
AMALGAMATE ATTRIBUTE DATA FOR AN COMBINE FILE
A new attribute file can be generated from an attribute file and a combine file by selecting AMALGAMATE ATTRIBUTE DATA FOR AN COMBINE FILE. The combine file defines new zones (or site catchments) in terms of the names referenced by the attribute file.
For example, you may define sales territories in terms of postal districts and put the definition in a combine file (manually or via territory definition). You would then amalgamate both the geographic file of postal district boundaries and any attribute files based on postal boundaries to produce files for mapping.
Attributes can also be derived from existing attributes by applying arithmetic operations to the attribute values via FORM ATTRIBUTES WITH ARITHMETIC EXPRESSIONS
A common application is preprocessing Census data before display to form the desired attributes.
Attributes are identified by the character # followed by a number, indicating the sequential position of the attribute on the input file e.g. #10 represents the tenth attribute). An example of an expression to form a composite attribute is:
(#1+#2)/2 > 0 < 1000
This creates a new attribute whose values are half the sum of the values from the first and second attributes on the input file. Any valid arithmetic expression is acceptable. The output values are limited to the given range.
Functions available are:-
Functions removed from the PC version are:
Pi is referred to as PI.
Operators are:
Expressions are evaluated left to right and have a limit of 70 characters. Parentheses should be used to ensure there are no ambiguities.
The user must give a 30 character attribute description and 10
character units description for each new attribute that is generated.
The menu is of the following form:
SUBSET FOR ZONES LIST
SUBSET FOR LINES LIST
SUBSET FOR SITES LIST
AMALGAMATE ZONES FOR A COMBINE FILE
JOIN LINE SEGMENTS FOR POLYGONS
SIMPLIFY (THIN) LINE SEGMENTS
EXTRACT BOUNDARY SEGMENTS
Often the geographic region covered by a geographic file will be much larger than is required. Geographic files can be subset (windowed) on the basis of a list of required display items (zones, sites, lines).
Line segments can be simplified to reduce the number of points that have to be processed. This is used to speed up display where the resolution of the digitised data are higher that that needed for display terminals.
Line segments that form polygons can be joined together into long segments. Where many short segments are used this process, in conjunction with simplification, can sustantially reduce the disk storage required and speed processing.
The zones in a geographic file can be amalgamated according to
a combine file to generate a new geographic file. The new file
contains the new zones. The same combine file can be used to generate
attribute data for the same new zones. For example, you may amalgamate
basic Census zones into zones at a higher level or into sales
territories.
Often digitised data are only available in polygon form for primitive
mapping systems. Polygons are all that are required for basic
choropleth mapping, but successful amalgamation of zones into
higher level zones (e.g. for territory definition) requires the
boundary segments. Usually the boundary segments will have been
digitised and used to form the polygons. A facility is available
to reverse the process. When Census data are processed, only the
lowest level of Census district need to be purchased along with
the lists of base districts that form higher level zones. Once
the boundary segments have been obtained they can be amalgamated
into the higher level zones.
Names files give lists of items (zones, sites,lines) that are to be processed. These lists can be generated from other types of files. These options are particularly useful when the names files are to be modified.
The menu is of the form:
SAVE ATTRIBUTE FILE NAMES AS A NAMES FILE
SAVE GEOGRAPHIC FILE ZONES AS A NAMES FILE
SAVE GEOGRAPHIC FILE LINES AS A NAMES FILE
SAVE GEOGRAPHIC FILE SITES AS A NAMES FILE
EDIT A NAMES FILE
For example, you may output the names from a Census attribute
file to a names file, edit it with a word processor and the use
it to subset a census boundary (geographic) file to produce the
desired map region.
Options are provided to output internal files as data files so they can be modified with word-processors for further processing. The menu is of the following form:
GENERATE ATTRIBUTE TEMPLATE DATA FILE
OUTPUT NAMES DATA FILE
OUTPUT ATTRIBUTE FILE IN SIMPLE (SAS) FORMAT
OUTPUT COMBINE DATA FILE
Names files can be edited to change the lists of items used for processing.
Attribute files can be output in simple database format.
Combine files can be modified as part of the definition of territories and sites.
Attribute templates can be generated for preparation of attribute
data with a word-processor. This is also useful for displaying
new boundary data when you have no attribute file. The file can
be input as a database format attribute file.
Geographic data, such as Census boundaries, are often supplied
as lines which have to be connected to form polygons or complex
lines.
Zone boundary data can be supplied either as the complete set of points for the outsides of each polygon or as the line segments that make up the boundaries.
Most segments will be common to two polygons so only about half the number of points are required. The segment form also allows zones to amalgamated into larger zones (by dropping internal segments) and to be thinned (by dropping excess points).
The segments form of data is preferred to polygon formats.
The build process takes line segments and joins the ends together to form polygons. The names of the zones on each side of the segments are used to derive the zone names.
Complex polygons are handled. Zones can be made up of many polygons, both disjoint polygons and polygons within polygons. The display order of the polygons are calculated so e.g islands within lakes within zones all appear.
Line segments can also be built into complex lines to which attribute data can be assigned.
It is usual to line simplify (thin) the segments before building as many digitised boundary files (e.g. census) are at a much higher resolution than require for the display. Joining of line segments and further thinning may follow.
If the message"TOO MANY POINTS IN POLYGON" appears you will have to line simplify your data. The building process can use a lot of disk space, effectively the product of the max number of polygons in a zone and the number of zones. Options are provided to help control this.
When the line segments were generated from spatial operations,
arithmetic roundoff can produce slightly different endpoints.
A tolerance factor can be given to help join faulty points. The
tolerance is usually zero.
The algorithm assumes that the segments have been produced on a proper digitising system and are correct e.g. it is assumed that end-points meet and the segments do not cross. Problems such as repeated segments, missing segments etc may cause problems. Ensure you use the program with trace turned on. If necessary turn on debug and look at the OZGIS.OUT file.
Use the file interrogation option to find the statistics on the geographic file
e.g. the number of zones.
The top menu option PREPARE DATA FOR DISPLAY can be used to generate
a prototype attribute file (simple format) from the zones in the
geographics file and hence get some test data that can be entered
via IMPORT DATA FILES to form an attribute file. Displaying both
files via SIMPLE CENSUS-TYPE MAPPING will allow the file to be
checked.
Building example.
The OzGIS system was designed to provide advanced mapping capablilities that could be interfaced to other systems such as:
The main software systems that are of value are spreadsheets and database systems for handling attribute and other data. These software systems (e.g. Lotus, Excel, MS access, Paradox) are easy to use and are growing in sophistication.
The OzGIS system interfaces to these systems via the Lotus WK1 file format.
Data must be held in a tabular format where the first column is ALWAYS the primary key and is the same as the map identifiers (and usually alphanumeric)
Other columns depend on the type of data.
WK1 format data can be imported into OzGIS via menu options in
the data entry process and exported via options in the data preparation
module.
Data from spreadsheets can be both imported and exported in WK1 format.
The spreadsheet must be set up in a fixed format:
e.g. the file DEMO123.dat can be read into the spreadsheet. It should look like:
| POPULATION | GROWTH | SALES | ||
| NUMBER | $ | |||
| ABBOTSFORD | 7418 | 237 | ||
| BURWOOD | E | 9925 | 955 | |
| CONCORD | 8984 | 202 | ||
| CROYDON | N | 9369 | 298 | |
| CROYDON | W | 735 | ||
| FIVE | DOCK | 9903 | 716 | |
| HABERFIELD | 727 | |||
| HOMEBUSH | 6631 | 704 | ||
| HUDSONPARK | 4668 | 71 | ||
| MORTLAKE | 1725 | 198 | ||
| STRATHFIELD | 6285 | 663 | ||
| YARALLA | 9875 | 516 |
For example, with Microsoft Excel for Windows, the test file can
be read by choosing the option "Open" from the "File"
menu and giving the test file as \OZDATA\DEMO123.WK1. A spreadsheet
in the above format can be output by selecting the "Save
As" option from the "Files" menu and using the
WK1 format option.
The first column of the spreadsheet can be output as a WK1 file and then imported into OzGIS as a names file to control the processing.
A names file can be exported as a single column WK1 file and hence used to initialise a spreadsheet.
Names can also be output from a geographic file, where the list
is one of the zone names, line names or site names.
Site names and their (X,Y) locations can be exported as WK1 files.
Points output from a spreadsheet can be input as a points geographic
file. The columns must have names called exactly "X"
and "Y". You can also assign positive numeric feature
codes by a column called exactly "Feature Code". If
the column is used, a feature code must exist for every point
(use zero if not required).
A combine file containing the definitions of either territories
or site catchments can be exported from OzGISas a WK1 file. The
column names are "Territory" and "Weight"
(the first column is the zone name).
You can export a column called "Address" as a WK1 file
from a spreadsheet and import it into OzGIS for reformatting as
a data file that can be used for geocoding.
The projection options will process a geographic file to form a new geographic file converting either from (Longitude,Latitude) to a projection or in the reverse direction.
Often projections will not be of concern, as map data will be used as supplied. However, if data comes from several sources in different projections, the files may have to be converted to a common coordinate system. You will have to have a basic knowledge of the projection you want to use
e.g. that AMG is UTM with the Australian Spheroid and a false origin
(500000,10000000).
The options are based on public domain software from USGS.
Projections processing is initiated by selecting MAP PROJECTIONS from the top menu
The main menu is:
CHOOSE FROM PROJECTION SET 1
CHOOSE FROM PROJECTION SET 2
CHOOSE FROM SPHEROID SET 1
CHOOSE FROM SPHEROID SET 2
DEFINE NON-STANDARD UNIT
WRITE PROJECTION DEFINITION INTO GEOGRAPHIC FILE
TRANSFORM LAT / LONG FILE TO PROJECTION
TRANSFORM PROJECTION FILE TO LAT / LONG
DISPLAY PROJECTION PARAMETERS FOR GEOGRAPHIC FILE
Vertices are stored in single precision in OzGIS (there is not
enough memory on the PC to do anything else). This means an accuracy
of seven digits, so some values may not be accurate e.g. UTM may
be a few metres out.
Latitude / longitude data must be given with units degrees.
Latitudes are negative in the Southern hemisphere.
Usual value ranges are:
Longitude -180 to +180
Latitude -90 to +90
Note that the X value in data files is the longitude.
examples: (-100.0,50.0) i.e. longitude -100, latitude 50
(145.0, -42.0) a point in Tasmania
Several projections are supported:
Several spheroids are available. The default is either Clarke 1866 or the 6370997 metre sphere where a radius is asked for.
The parameters of the projection are stored in the geographic file. When the data are first entered the projection is usually set to 'undefined', unless it is known e.g. Census boundary data are usually set to geographic (lat/long units degrees) by the data entry process.
The first operation is often to define the projection of a new geographic file and store the parameters in the file header. Hence you have to choose the projection, spheroid if non standard, and then the option WRITE PROJECTION DEFINITION INTO GEOGRAPHIC FILE.
Transformation is to and from lat/long. Hence conversion from
one projection to another has to take place in two steps.
Selecting File->Print will enable the displayed map to be output
to your printer.
You will probably need to use the printer setup option first and
use landscape.
You will usually use a device file that has a white background
if you are printing on white paper.
The standard WINDOWS facility of Alt+Print screen can be used
to load the current map into the clipboard. From there it can
be imported into other packages e.g. into a Word document.
Colour slides can be successfully produced by photographing the screen.
The room has to be dark and any lights on the PC covered. Watch for reflections around the edge of the screen (blacken around the screen).
You will have to experiment. Initially bracket exposures.
Lenses with long focal lengths reduce the curvature of the screen.
An initial setting is:
250mm lens
200 ISO film
f/8 at 1 second
Territories can be defined in terms of zones (polygons) in some
displayed base map.
Usually territories are to be developed from base zones according to some criterion; e.g. Sales territories should all have similar sales potential; e.g. School districts should have similar numbers of children.
The operations are as follows.
First choose the New pulldown menu:
START NEW SET OF TERRITORIES INTERACTIVELY
START NEW SET OF TERRITORIES FROM COMBINE FILE
This gives the choice of starting a new set of territories by selecting regions with the box-cursor, or reading in a pre-defined set of territories off a combine file that is probably the result of a previous run of OzTerr.
The Define menu is used to specify the zones in each territory
DISPLAY TERRITORY NAMES
DEFINE NEW TERRITORY
DELETE A TERRITORY
ADD ZONES SELECTED WITH BOX-CURSOR TO A TERRITORY
ADD A ZONE SELECTED WITH CURSOR TO A TERRITORY
DELETE ZONES SELECTED WITH BOX-CURSOR FROM A TERRITORY
DELETE A ZONE SELECTED WITH CURSOR FROM A TERRITORY
CHANGE BASE ZONE ATTRIBUTES
CHANGE THE QUANTISATION METHOD
OVERLAY MARKERS FOR SITES IN GEOGRAPHIC FILE
OVERLAY NAMES FOR SITES IN GEOGRAPHIC FILE
OVERLAY LINE SEGMENTS FROM A GEOGRAPHIC FILE
OUTPUT TERRITORY NAMES AS GEOGRAPHIC FILE
OUTPUT TERRITORIES AS COMBINE FILE
You define territories using the options:
DISPLAY TERRITORY NAMES
DEFINE NEW TERRITORY
DELETE A TERRITORY
Usually you are trying to balance territories e.g. you may display an attribute that is number of customers and the try to give each salesman a territory with about the same number of customers. To do this you define the correct number of territories making a guess at their size and then shuffle the zones between the territories while monitoring the results by using "Display Map" to display the map. The options relevant to modifying territories are:
ADD ZONES SELECTED WITH BOX-CURSOR TO A TERRITORY
ADD A ZONE SELECTED WITH CURSOR TO A TERRITORY
DELETE ZONES SELECTED WITH BOX-CURSOR FROM A TERRITORY
DELETE A ZONE SELECTED WITH CURSOR FROM A TERRITORY
You can add overlays to the displayed map to provide "navigation" with:
OVERLAY MARKERS FOR SITES IN GEOGRAPHIC FILE
OVERLAY NAMES FOR SITES IN GEOGRAPHIC FILE
OVERLAY LINE SEGMENTS FROM A GEOGRAPHIC FILE
Finally the territory definitions can be output to a combine file that can be used to amalgamate the base zones and related attributes (see data preparation) to get a geographic and attribute file for mapping by using the option OUTPUT TERRITORIES AS COMBINE FILE.
You should have line segments data for amalgamation. If you started with polygon data, the polygons will simply be renamed during the amalgamation process.
You can also output a points geographic file that can be used
as an overlay to label the territories on a map by using OUTPUT
TERRITORY NAMES AS GEOGRAPHIC FILE.
Many organisations have data which are spatially referenced by addresses, such as customer databases. These data can be shown on a zones map by accumulating the data within each postal district and displaying the results using digitised postal district boundaries. Examples are total number of customers and average sales amount.
Digital data are now becoming available that contain address information e.g. the US Census TIGER data. These data enable the locations of the attribute data to be extracted as points and maps produced with or without related attribute data.
The OzGIS system allows digitised road data and their associated addresses to be processed. Sets of addresses can be processed to produce geographic files of point locations. These point files can then be displayed in the usual ways, either as symbols or names as map overlays or as sites sized according to some attribute data.
For example, a bank may want to extract points using the addresses
of some customers and then map the average monthly account balances.
An address is made up of three parts, a number, a name and a postal code. Examples are:
123 Main Street 654321
Hyde Park
12 Funny Farm Drive, Hicksville 2601
1. The number is a simple integer. Common variations such as 22A, 5-6, 5/66 etc are not supported. If a number is not given the point will be placed in the centre of the geographic feature.
2. The name must be given, and is the main part of the address for matching.
3. The postal district is an integer number that helps processing
in cases where the same address name is used in different districts.
It need not be given.
Lines data can be entered with the normal process. Addresses are supported for TIGER data and data in standard form. Other formats will be supported according to availability of data and demand.
Only line data is supported as that is what is currently available. Typically the data will be roads.
Two ranges of street numbers will usually be associated with a road, a set of odd numbers down one side and even numbers down the other e.g. a digitised line segment may have road name "Hollywood Boulevarde" and number ranges 111 to 179 and 120 to 220.
A road may also have one range (e.g. 1 to 200) or no range may
be given. The order of the road numbers defines the direction
of the road. The direction does not have to be the same for the
odd and even numbers. If two ranges are given and one is not odd
and the other even, a single range is derived from the limits,
but the direction must be the same as defined by the two ranges.
An option is provided in the data preparation process to match addresses in a data file with those in the digitised line data in a geographic file. The major difficulty is the matching of the road names allowing for differences in spelling.
After a match is found, the number in the given address is used to find the distance along the road (using the ranges) and hence a location is calculated.
The set of addresses are given on a data file that has the following:
1. An identifier that can be used to attach attribute data to the point and which can be used as a label on maps. If no identifier is given the road name will be used. This identifier would often be a database primary key.
2. The road number. If not given the generated point will be the centre of the road.
3. The road name. Mandatory.
4. The post (zip) code. Optional.
A geographic file of points is generated. Any addresses that cannot
be matched are listed on the OZGIS.OUT file.
Matching takes place on upper case characters i.e. case is not significant e.g. "Main St" and MAIN st" match.
Multiple blanks are removed e.g. "Grand Parade" matches "Grand Parade".
A parameter file is used to convert parts of the names. This is commonly used to handle abbreviations e.g. ROAD and RD.
Matching is controlled by a level:
Level 1. Every character in the names in the geographic and data files must be the same e.g. "PHREDS ROAD" and PHRED ROAD" are not the same.
Level 2. Every character of the shorter name must match the other e.g. "phred" would match the above two strings.
Level 3. The first word in each name must match e.g. "Bloggs Street" and "Bloggs Ave" match.
Level 4. Matching is carried out by using derived names e.g. vowels are all treated the same, repeated letters are removed, non alphabetic characters are all the same.
Level 5. Matching uses the "soundex" algorithm
Address matching is an option in the data preparation process. Select PREPARE DATA FOR DISPLAY from the top menu, which gives the menu:
TUTORIALS & SYSTEM INFORMATION
PROCESS GEOGRAPHIC FILES
PROCESS ATTRIBUTES FILES
PROCESS NAMES FILES
OUTPUT EXTERNAL DATA FILES
ADDRESS MATCHING
CHANGE DEVICE FILE
So you choose ADDRESS MATCHING, which displays the menu:
EXACT MATCHING FOR POINTS OVERLAYS
MATCH FOR START OF ADDRESS FOR POINTS OVERLAYS
MATCH FOR FIRST WORD OF ADDRESS FOR POINTS OVERLAYS
DESPERATION MATCHING FOR POINTS OVERLAYS
EXACT MATCHING FOR SITE MAPPING
MATCH FOR START OF ADDRESS FOR SITES MAPPING
MATCH FOR FIRST WORD OF ADDRESS FOR SITES MAPPING
DESPERATION MATCHING FOR SITES MAPPING
These options correspond to the 4 matching levels for either point overlays or site mapping.
You have to specify a number of files:
1. the geographic file that contains the roads and the road names and address limits
2. Your data file containing the addresses to be matched
3. A parameter file of abbreviations to help the matching process e.g. AVE is defined as the abbreviation for Avenue
4. the name of the geographic file to be generated with the points location After you have generated the points geographic file you should check the file OZGIS.OUT to see how well the addresses were matched. You may then want to change some of the addresses in the data file to improve the hit rate.
You can now map the data with the OzGIS program. This is covered in other chapters, but briefly:
DISPLAY GEOGRAPHIC FILES (NO ATTRIBUTES) is used to display the points as symbols.
You would probably then use DEFINE GEOGRAPHIC OVERLAYS and add your roads file as a lines overlay and also overlay the names of the points.
DISPLAY SITES FOR AN ATTRIBUTE FILE would be used if you have attribute data for the points. You would probably add the roads as a lines overlay and the identifiers as a names overlay.
DISPLAY ZONES AND SITES FOR TWO ATTRIBUTE FILES could also be used if you want to display other data such as Census data as a zones map underneath the points with their attribute data.
The points could of course be added as overlays to any map.
You specify the addresses you want to match in a data files with fixed format records:
10 bytes Identifier. If blank the road name is used (first 10 bytes)
50 bytes Address
For example, the demonstration file DEMOMTCH.DAT looks like:
EXAMPLE ADDRESSES FOR MATCHING - DEMOMTCH.DAT
ADDRESS001 1 GReat north road 2600
666 GReat north road 2600
JOE BLOGGS 333 GReat north road 2600
ADDRESS004 GReat north road 2600
333 GReat north road
PIZZA KING GReat north road
ADDRESS007 333 GReat 2600
HARRY S 333 GReat north rd 2600
ADDRESS009 333 GReet narth read 2600
ADDRESS011 666 GReat north road 2600
ADDRESS012 666 Molonglo Gorge 2600
ADDRESS013 Molonglo Gorge
11 Northbourne Ave 2602
ADDRESS015 44 Northbourne Ave 2600
ADDRESS016 10 Northbourne Ave 2600
ADDRESS017 68 Northbourne Ave 2600
ADDRESS018 57 Northbourne Ave 2600
ADDRESS01940 EPPING HWY
ADDRESS020 33 EPPING HWY
A parameter file must be given to allow for abbreviations such as ST, AVE, RD
A sample file from the USA Census TIGER documentaion is provided \OZGIS\USA.PRM
You should set up your own abbreviation file. The shorter it is, the faster will be the matching process.
The first record of the file is a comment, and each following record is:
30 bytes text
10 bytes abbreviation
The file must be in upper case, and the abbreviation must be shorter than the text string.
The demonstration file is DEMOMTCH.PRM:
Address matching parameter file DEMOMTCH.PRM
AVENUE AVE
BOULEVARD BLVD
CIRCLE CIR
DRIVE DR
FREEWAY FWY
HIGHWAY HWY
MOTORWAY MTWY
PARKWAY PKY
PLACE PL
ROAD RD
STREET ST
The results of the matching process are written to the log file OZGIS.OUT Each data record is listed with either "MATCHED", "DUPLICATE" or "REJECTED". When the names match both the data and geographic file addresses are listed as well as the level of the match. The output will be of the form:
======= ADDRESS MATCHING AT LEVEL 4 ======
GEOGRAPHIC FILE demoaddr
ADDRESSES FILE demomtch
PARAMETER FILE demomtch
MATCHED 333 GReat north road 2600
MATCHED 666 GReat north road 2600
NO MATCH 666 Molonglo Gorge 2600
NO MATCH 68 Northbourne Ave 2600
MATCHED 11 EPPING HWY 0
MATCHED 33 EPPING HWY 0
NO MATCH 33 EPXXING HWY 0
New geographic files can be generated as the result of spatial
operations such as union and intersection between the spatial
objects in two input geographic files.
The options have not been fully tested.
The operations take place between the objects in two input geographic files, with the resultant objects being output to a new geographic file. The following operations are supported:
Two levels of polygons will be supported:
1. Simple polygons Single polygons are processed. There is no regard for polygons inside other polygons. Polygons with the names OUTSIDE or INSIDE are ignored. This will often be all that is required. These data can have been entered into the system as one of the polygonal formats supported (SAS, Atlas etc).
2. Complex polygons NOT IMPLEMENTED YET This handles zones
which are made up of any mixture of polygons, some of which can
be inside others to a considerable depth. The results of the polygon
processing is a file of line segments that can be built into polygons
with the zone/polygon building process.
Processing can take place for a range of feature codes or the
whole of the files can be processed. A new feature code must be
specified for the generated objects. Optionally the existing feature
codes for both files of objects can be added as well.
When the SPATIAL OPERATIONS item is selected from the top menu the following menu appears:
INTERSECT POINTS (SECONDARY) WITH SIMPLE POLYGONS (PRIMARY)
INTERSECT LINES (SECONDARY) WITH SIMPLE POLYGONS (PRIMARY)
INTERSECT SIMPLE POLYGONS WITH SIMPLE POLYGONS
UNION OF SIMPLE POLYGONS WITH SIMPLE POLYGONS
INTERSECT POINTS WITH SIMPLE POLYGONS FOR FEATURE CODES
INTERSECT LINES WITH SIMPLE POLYGONS FOR FEATURE CODES
INTERSECT POLYGONS WITH SIMPLE POLYGONS FOR FEATURE CODES
UNION OF POLYGONS WITH SIMPLE POLYGONS FOR FEATURE CODES
You select the appropriate option. You can either process all the geographic data or subset it for a feature code range. Then you have to give the names of the two input geographic files. As indicated by the menu items, the primary geographic file is always a file of polygons while the secodary geographic file is the points or line segments or polygons.
You also have to give a name for the geographic file that will be generated.
You always have to provide a feature code (a positive number) for the generated objects, and can optionally have the feature codes from the intersected (or unioned) pairs of objects included in the new objects.
Polygons are not directly generated. If you intersect or form
the union of polygons with polygons the output is line segments
which then have to be built into polygons with the zone/polygon
building process.
Algorithms are provided to aid in site selection for applications
such as the siting of new schools, shopping centres or fast-food
outlets.
The facilities are based on ILACS (Interactive Location Allocation
in Continuous Space) by Mike Goodchild.
The selection of a site for some service has two parts:
1. Location of the site.
2. Allocation of the data points to the site.
The data are a set of point locations and attribute data giving
the "demand" at each point.
There can be up to 5 current solutions, referred to by number. Each provides storage for a complete solution, giving the locations, optional capacities and mobilities of each of the sites
There is always a current solution (initially number one).
The contents of each solution are intially zero, so each site is located at (0,0) with zero capacity and is free to move.
The Alternating and Tornqvist algoriths take the contents of the
current solution and place the generated optimum solution into
a new, specified current solution.
The storage available for the mattrix of site/demand points is limited, and large numbers of demand points allow smaller numbers of sites to be allocated.
Sites are referred to by name. These are initially SITE001, SITE002 etc, but they can be renamed.
Sites can be mobile or fixed during optimisation; many situations have existing fixed sites and are allocating some new facilities. e.g. the schools in a city may be investigated with the view of keeping most, building a few new ones, and closing some down.
Site locations can be set to random locations within the map area or to a random sample of the data points.
The capacities of the sites can be initialised by dividing the total demand equally among them.
Sites can be located with the cursor / mouse.
A geographic points file gives a set of locations from which the demand is considered to come. Typically the points will be thye centroids of Census polygons. The points are displayed as symbols and any line segments (typically the boundaries of Census district polygons) will also be displayed.
Points should have unique names, but the case of multiple polygons
within Census districts (and hence the same name) are handled
by dividing the attribute value equally between them.
The attribute file gives the demand at the point locations. The data are typically demographic data such as Census data.
The data depend on the application and will often be prepared by applying arithmetic operations to basic attribute data.
In some cases the data are obvious e.g. Census data giving the total population in the age group 11 to 17 years may be used when siting high schools. Other cases may be more complicated and models developed by statistical analysis of other data e.g. an attribute for siting a maternity hospital may be 20% of women aged 17 to 25 years, 25% of women aged 26 to 35 years and 5% of the number of women aged 36 to 45 years. Sometimes a simple attribute may be found to correlate well enough to be used as an indicator variable.
The algorithmns work with positive integer values, so arithmetic
operations may have to be used to scale and offset the attribute
data. The data values should have a large range.
An allocation consists of a matrix of assignments of demand from each point to each site. Only one allocation is active at any time.
An allocation is defined explicitly by the allocation operation
(the point of Minimum Aggregate Travel using steepest descent)
or implicitly by the use of the Alternating or Tornqvist algorithms.
A number of parameters are used to control operations. They have default values and can be changed during a session.
Travel limitations such as rivers can be simulated by specifying straight line barriers with the mouse / cursor. Barriers can also be used for other situations such as political boundaries.
Freeways and travel speed ratios can also be specified.
The current allocation is continually output to a geographic file and displayed. The file name can be changed, and the file can be used for other mapping applications. The file contains:
A combine file can be generated giving the points allocated to each site. This can be used to accumulate attribute data for mapping at the sites in the generated geographic file. It could also be used to amalgamate polygons to form territories (if there are no repeated points i.e. weights < 1. In this case you will have to output the combine file as a data file and edit it).
The current allocation can be shown on the screen, and a full report can be output to the usual OZGIS.OUT file.
The allocation can be saved to (and restored from) a file.
Location / allocation example
Catchments can be defined as contours around sites and the attribute
data extracted from base zones (usually Census data) for mapping.
A common requirement is to know the demographics of an area surrounding a site.
For example, a shopping centre manager would like to know how many customers of a particular type should be attracted to the centre.
The basic source of demographic data is usually Census data. The aim of the site catchment software is to determine weights to be applied to Census districts around a site so values can be accumulated.
As it is expected that the attraction to a site will fall away with distance, the procedure is to define a set of contours around each site.
For example, it may be decided that 95% of people living within 10KM of a hospital will go there in am emergency, 50% within 20KM outside that, and 10% within 30KM.
The contours are defined interactively on the screen, and their shape will reflect other influences such as barriers and competition. For example, the contours may be drawn for a site at location X as:
*
* *
* *
* * * * *
* * * *
* * X * *
* * * *
* * *
*
After the catchment contours have been defined they can be overlayed on the underlying Census boundaries to find which Census districts lie within each contour. The Census districts, the proportion within the contours and the contour levels are used to produce a list of districts and their weights for each site. The lists are output as a combine file which can be used to amalgamate Census data for mapping.
The site names and locations are output as a geographic file that can be used with the attribute file to map the sites.
Geographic files containing the contour lines and other site definition
graphics can also be produced for use as an overlay on maps.
Sites are intiially defined as circles on the ground of a given size. The map projection must be known to do this. The geographic files must be Latitude Longitude with units of degrees.
Census boundary files are usually in this form.
You may have to use the projections options. In particular, even if the file is lat. long. you may have to write that information into the file header by:
Select CHOOSE FROM PROJECTION SET 1 and then GEOGRAPHIC LATITUDE LONGITUDE Then use WRITE PROJECTION DEFINITION INTO GEOGRAPHIC FILE
You will find that the process of intersecting the catchment contours and the base map polygons is slow. As the speed depends on the number of points in the polygons and as the process is approximate it is suggested that the data preparation option be used SIMPLIFY (THIN) LINE SEGMENTS
The catchments are held as latitude / longitude polygons so are independent of the base map i.e. you can use one base map during definition and another during the intersection process. The process assumes an even population distribution across the base map zones, so the smaller the zones the more accurate the results would be.
Note that the current set of sites being processed must always
fit on the base map.
The system aims to provide facilities for analysis of sites for the definition of site locations and catchments, the retrieval of data, development of models and display of results.
The base of the process is the catchment file.
A catchment file holds the definition of several sites. The sites have some common grouping (e.g. all part of the same retail chain) and all fit on the same base map.
A typical analysis would involve several catchment files, e.g. several sets of sites each for a different organisations( e.g. several sets, each defined on different base maps to increase resolution. )
Site definition is carried out for a current set of sites. These sites can be modified and new sites defined. A base map is always displayed and all the current sites must fit on the displayed map.
Also defined for assistance are any other catchment files relevant to the analysis Site symbols, names and catchments are displayed if they fit on the map. These sites cannot be modified.
A catchment file contains the following information for each site.
The whole process is iterative with catchments being modified and the results mapped.
The catchment definition menus provide the options (using a displayed base map):
INCLUDE SITES FROM CATCHMENT FILE Enables existing sites to be considered.
ADD A NEW SITE
DELETE A SITE
RENAME A SITE
Provides basic site control.
REPOSITION SITE LOCN, NAME OR SYMBOL Enables shuffling of displayed site information when sites are crowded.
MODIFY SITE CONTOURS Enables several contours to be defined for a site as circles or digitised simple polygons. The contours can reflect the interaction between sites and any barriers.
Contours are essentially simple i.e. they are assumed to be concentric, and do not cross.
CHANGE DISPLAYED REGION Enables zooming and panning of the base map.
TEMPORARILY OVERLAY OTHER CATCHMENT FILE ON BASE MAP Enables other site catchment files to be added as overlays.
OVERLAY GEOGRAPHIC FILES ON BASE MAP Enables lines, points etc to be added to the base map.
INCLUDE POINTS FROM GEOGRAPHIC FILE Enables a set of sites to
be defined as circles (all same radius) at locations given in
the file.
The Digital Chart of the World (DCW) is a fabulous world-wide database available on 4 CD-ROMs for the cost of distribution.
Points, lines and text data can be imported in VPF format. Polygons can be built from the lines with some restrictions.
The data entry process is designed so only the required files
are processed. This means that you do not have to have a CD-ROM
drive but can copy the required files from another PC.
The data comes on four CD-ROMS. Each contains a copy of the world-wide BROWSE library and one other library covering a part of the world
You obviously choose which library you want first.
The BROWSE data base contains data files that cover the whole world, but the other detailed libraries contain a hierarchy of file directories of data for 5 degree square tiles.
The first process is finding which directories contain the data
you require.
Processing requires two files:
1. a file that contains the actual data
2. A feature attribute table file that defines the feature codes of the
Pairs of files are:
Where xx is the main directory
The DCW files are binary. A VPFDUMP program comes with the data and can be used for inspection.
A similar program OZDCW is supplied. This can also be used to inspect data files.
OZDCW must be used to convert the binary DCW files to ascii files in preparation for data input i.e. the raw DCW files cannot be imported. Typing OZDCW FILE will list the file
Hence you often use "OZDCW file | MORE"
To process a file for importing use e.g. "OZDCW file >
dataFile"
The first file to look at is the coverage attribute table at the highest directory level for the library you want. This is called CAT.
e.g. type "OZDCW BROWSE\CAT. | MORE" to find what is in the BROWSE library
Digital Chart of the World file: \usr\local\DCW\BROWSE\CAT.
191L;
Coverage Attribute Table;-;
**DCWcolumns ====================
ID =I, 1,N,Row Identifier,-,-,:
COVERAGE_NAME =T, 8,P,Coverage name,-,-,:
DESCRIPTION =T, 50,N,Coverage description,-,-,:
LEVEL =I, 1,N,Topology level,-,-,:;
**DCWdata ===========================
**DCWrow --------------------
1
CO
ONC Compilation Date
3
**DCWrow --------------------
2
DV
Data Volume
3
**DCWrow --------------------
3
DN
Drainage
3
**DCWrow --------------------
4
GR
Geographic Regions
3
**DCWrow --------------------
5
DA
Hypsographic Data Availability
3
**DCWrow --------------------
6
IN
ONC Index
3
**DCWrow --------------------
7
PO
Political\Oceans
3
**DCWrow --------------------
8
PP
Populated Places
0
Hence Rivers etc are in the drainage coverage, Country boundaries in the
political directory PO etc
Suppose you want to find out the actual data available in the political coverage i.e. the PO directory.
type "OZDCW PO\INT.VDT | MORE"
Digital Chart of the World file: PO\INT.VDT
252L;
Political\Oceans Integer Value Description Table;-;
**DCWcolumns ====================
ID =I, 1,N,Row Identifier,-,-,:
TABLE =T, 12,P,Name of Feature Table,-,-,:
ATTRIBUTE =T, 16,P,Attribute Name,-,-,:
VALUE =I, 1,P,Attribute Value,-,-,:
DESCRIPTION =T, 50,N,Attribute Value Description,-,-,:;
**DCWdata ===========================
**DCWrow --------------------
1
POAREA.AFT
POPYTYPE
1
Land areas
**DCWrow --------------------
2
POAREA.AFT
POPYTYPE
2
Ocean areas
**DCWrow --------------------
3
POLINE.LFT
POLNTYPE
1
International Boundary
**DCWrow --------------------
4
POLINE.LFT
POLNTYPE
2
Coastline
**DCWrow --------------------
5
POTEXT.TFT
LEVEL
1
Land place names
**DCWrow --------------------
6
POTEXT.TFT
LEVEL
2
Ocean place names
**DCWrow --------------------
7
POTEXT.TFT
LEVEL
3
Ice Status
**DCWrow --------------------
8
POTEXT.TFT
LEVEL
4
Land place names (diacritical)
**DCWrow --------------------
9
POTEXT.TFT
LEVEL
5
Ocean Place names (diacritical)
**DCWrow --------------------
10
POTEXT.TFT
LEVEL
6
Mountain names
**DCWrow --------------------
11
POTEXT.TFT
LEVEL
7
Mountain names (diacritical)
**DCWrow --------------------
12
POTEXT.TFT
LEVEL
8
Island names
**DCWrow --------------------
13
POTEXT.TFT
LEVEL
9
Island names (diacritical)
**DCWrow --------------------
14
POTEXT.TFT
LEVEL
10
Desert names
**DCWrow --------------------
15
POTEXT.TFT
LEVEL
11
Desert names (diacritical)
**DCWrow --------------------
16
POTEXT.TFT
SYMBOL
1
Black annotation
**DCWrow --------------------
17
POTEXT.TFT
SYMBOL
4
Blue annotation
Each entry tells you what it is, the attribute feature table you have to use,
and the feature code e.g. the entry:
**DCWrow --------------------
4
POLINE.LFT
POLNTYPE
2
Coastline
Tells you that to to extract the Coast outline you need feature
code 2
To map the whole world use the BROWSE library.
First look at the coverage attribute table, which basically tells
what is in the various directories for the library:
Type "VPFdump \usr\local\DCW\BROWSE\CAT. | MORE"
191L;
Coverage Attribute Table;-;
ID =I, 1,N,Row Identifier,-,-,:
COVERAGE_NAME =T, 8,P,Coverage name,-,-,:
DESCRIPTION =T, 50,N,Coverage description,-,-,:
LEVEL =I, 1,N,Topology level,-,-,:;
1 CO ONC Compilation Date
3
2 DV Data Volume
3
3 DN Drainage
3
4 GR Geographic Regions
3
5 DA Hypsographic Data Availability
3
6 IN ONC Index
3
7 PO Political\Oceans
3
8 PP Populated Places
0
So rivers will be in the DN directory, towns in the PP directory etc.
In this example look at to PO directory...
As before, start by looking at the Integer Value Description table:
type "VPFdump \usr\local\DCW\BROWSE\PO\INT.VDT : MORE"
252L;
Political\Oceans Integer Value Description Table;-;
ID =I, 1,N,Row Identifier,-,-,:
TABLE =T, 12,P,Name of Feature Table,-,-,:
ATTRIBUTE =T, 16,P,Attribute Name,-,-,:
VALUE =I, 1,P,Attribute Value,-,-,:
DESCRIPTION =T, 50,N,Attribute Value Description,-,-,:;
1 POAREA.AFT POPYTYPE 1 Land areas
2 POAREA.AFT POPYTYPE 2 Ocean areas
3 POLINE.LFT POLNTYPE 1 International Boundary
4 POLINE.LFT POLNTYPE 2 Coastline
5 POTEXT.TFT LEVEL 1 Land place names
6 POTEXT.TFT LEVEL 2 Ocean place names
7 POTEXT.TFT LEVEL 3 Ice Status
8 POTEXT.TFT LEVEL 4 Land place names (diacri tical)
9 POTEXT.TFT LEVEL 5 Ocean Place names (diacr itical)
10 POTEXT.TFT LEVEL 6 Mountain names
11 POTEXT.TFT LEVEL 7 Mountain names (diacriti cal)
12 POTEXT.TFT LEVEL 8 Island names
13 POTEXT.TFT LEVEL 9 Island names (diacritica l)
14 POTEXT.TFT LEVEL 10 Desert names
15 POTEXT.TFT LEVEL 11 Desert names (diacritica l)
16 POTEXT.TFT SYMBOL 1 Black annotation
17 POTEXT.TFT SYMBOL 4 Blue annotation
The major interest is the coast and country boundary lines, given by line feature table POLINE.LFT with the feature column POLNTYPE having values 1=International Boundary or 2=Coastline
We will also extract the major place names, feature code 1.
You need pairs of files; the data goes into a .DAT file and the attribute table file into an OzGIS parameter file:
First the lines:
OZDCW PO\POLINE.LFT > \mapping\DCWLINE.PRM (where mapping is the directory, say)
OZDCW PO\EDG. > \mapping\DCWLINE.DAT
and the text\points data:
OZDCW PO\POTEXT.TFT > \mapping\DCWTEXT.PRM
OZDCW PO\TXT. > \mapping\DCWTEXT.DAT
Now run OzGIS and import geographic data for two pairs of files DCWLINE and DCWTEXT You select the type of DCWdata being imported (lines and text) and specify the feature codes required (see above).
Then map geographic data. Display DCWLINE lines for feature code 2 (the coast).
Then overlay lines for feature code 1 (the internal country boundaries,
and overlay DCWTEXT as names at points.
The detailed libraries contain the data in 5 degree square tiles. Each tile is in a lower level directory. To be inconsistent, the feature table files are still in the top level directories.
Suppose we want to map the Mergui Peninsular area, Latitude about 12N, longitude about 98E.
The first thing you have to do is find which directory contains the data
The Face bounding rectangle table tells the extent of each tile
Type "VPFdump \usr\local\DCW\SASAUS\TILEREF\FBR. | MORE"
239L;
"FBR: Face Bounding Rectangle Table";-;
ID =I, 1,P,Row ID,-,-,:
XMIN =F, 1,N,Minimum X Coordinate,-,-,:
YMIN =F, 1,N,Minimum Y Coordinate,-,-,:
XMAX =F, 1,N,Maximum X Coordinate,-,-,:
YMAX =F, 1,N,Maximum Y Coordinate,-,-,:;
1 -180.000092 -55.000000 180.000000 55.000000
2 45.000008 50.000000 50.000000 55.000000
3 50.000008 50.000000 55.000000 55.000000
4 55.000008 50.000000 60.000000 55.000000
5 60.000008 50.000000 65.000000 55.000000
6 65.000015 50.000000 70.000000 55.000000
7 70.000015 50.000000 75.000000 55.000000
8 75.000015 50.000000 80.000000 55.000000
9 80.000015 50.000000 85.000000 55.000000
10 85.000015 50.000000 90.000000 55.000000
11 -180.000092 45.000000 -175.000000 50.000000
12 25.000004 45.000000 30.000000 50.000000
13 30.000004 45.000000 35.000000 50.000000
14 35.000008 45.000000 40.000000 50.000000
....
229 75.000015 10.000000 80.000000 15.000000
230 80.000015 10.000000 85.000000 15.000000
231 85.000015 10.000000 90.000000 15.000000
232 90.000015 10.000000 95.000000 15.000000
233 95.000015 10.000000 100.000000 15.000000 <<<<<<<<<<<<<
234 100.000015 10.000000 105.000000 15.000000
235 105.000015 10.000000 110.000000 15.000000
236 110.000015 10.000000 115.000000 15.000000
237 115.000015 10.000000 120.000000 15.000000
...
So you need tile number 233. The tile reference attribute table gives the directory.
Type "VPFdump \usr\local\share\DCW\SASAUS\TILEREF\TILEREF.AFT | more"
94L;
Tile Reference Areas;-;
ID =I, 1,P,Row Identifier,-,-,:
TILE_NAME =T, 6,N,Tile Name,-,-,:;
1 \\
2 R\K\12
3 R\K\22
4 R\K\32
5 S\K\12
6 S\K\22
7 S\K\32
8 T\K\12
9 T\K\22
10 T\K\32
11 A\K\11
12 P\K\31
13 Q\K\11
14 Q\K\21
15 Q\K\31
16 R\K\11
...
227 S\G\23
228 S\G\33
229 T\G\13
230 T\G\23
231 T\G\33
232 U\G\13
233 U\G\23 <<<<<<<<<<<<<<<<<< coast
234 U\G\33
235 V\G\13
236 V\G\23
237 V\G\33
238 W\G\13
239 W\G\23
...
So the data are in sub-directory U\G\23
So to extract the required data from the PO (political) coverage you could:
OZDCW PO\POTEXT.TFT > \mapping\DCWTEXT.PRM for text
OZDCW PO\U\G\23\TXT. > \mapping\DCWTEXT.DAT
OZDCW PO\POLINE.LFT > \mapping\DCWLINE.PRM for line data
OZDCW PO\U\G\23\EDG. > \mapping\DCWLINE.DAT
OZDCW PO\POPOINT.PFT > \mapping\DCWPOINT.PRM for point data
OZDCW PO\U\G\23\END. > \mapping\DCWPOINT.DAT
Note that the feature table files can be large. If you are short of disk space you need only extract the part of the file that has the IDs covering those of the data file. For example, if you extract data by say:
OZDCW PO\U\G\23\END. > \mapping\DCWPOINT.DAT
Then the OZDCW program will print out the number of records. If you look at the start of the data file by:
MORE < \mapping\DCWPOINT.DAT
then you can find the ID of the first record.
Suppose the first ID is 1234 and there are 100 records, then you can extract just the required feature data by:
OZDCW -f 1234 -l 1334 PO\POPOINT.PFT > \mapping\DCWPOINT.PRM
The first and last record IDs have to cover the range of the data.
e.g. OZDCW -f 1000 -l 1500 PO\POPOINT.PFT > \mapping\DCWPOINT.PRM
As before you find the feature codes by looking at the INT.VDT file
Type " VPFdump \usr\local\DCW\SASAUS\PO\INT.VDT | more"
279L;
Political\Oceans Integer Value Description Table;-;
ID =I, 1,N,Row Identifier,-,-,:
TABLE =T, 12,P,Name of Feature Table,-,-,:
ATTRIBUTE =T, 16,P,Attribute Name,-,-,:
VALUE =I, 1,P,Attribute Value,-,-,:
DESCRIPTION =T, 50,N,Attribute Value Description,-,-,:;
1 POAREA.AFT POPYTYPE 1 Land
2 POAREA.AFT POPYTYPE 2 Open ocean
3 POAREA.AFT POPYTYPE 3 Polar Ice
4 POAREA.AFT POPYTYPE 4 Pack Ice
5 POAREA.AFT POPYTYPE 5 Shelf Ice
6 POLINE.LFT POLNTYPE 1 International boundary, Dejure
7 POLINE.LFT POLNTYPE 2 International boundary, Defacto
8 POLINE.LFT POLNTYPE 3 International boundary, Dejure and Defacto
9 POLINE.LFT POLNTYPE 4 Administrative boundary, primary
10 POLINE.LFT POLNTYPE 5 Administrative boundary, major
11 POLINE.LFT POLNTYPE 6 Treaty or occupancy line
12 POLINE.LFT POLNTYPE 7 Coastal Closure Line
13 POLINE.LFT POLNTYPE 8 Ocean demarcation Line
14 POLINE.LFT POLNTYPE 9 Ice line
15 POLINE.LFT POLNTYPE 10 Coastline
16 POLINE.LFT POLNTYPE 11 Ice\Water line
17 POLINE.LFT POLNTYPE 12 Seawall
18 POLINE.LFT POLNTYPE 13 International Date Line
19 POLINE.LFT POLNTYPE 88 Connector
20 POLINE.LFT POLNSTAT 1 Definite
21 POLINE.LFT POLNSTAT 2 Approximate boundary or fluctuating coastline
22 POLINE.LFT POLNSTAT 3 Indefinite boundary or u nsurveyed coastline
23 POLINE.LFT POLNSTAT 4 Manmade coastline
24 POLINE.LFT POLNSTAT 5 Undetermined coastline
25 POLINE.LFT POLNSTAT 6 Ice cliff (coastline or ice line)
26 POLINE.LFT POLNSTAT 7 River, when boundary
27 POLINE.LFT POLNSTAT 8 Poly closure line
28 POLINE.LFT POLNSTAT 9 None
29 POPOINT.PFT POPTTYPE 1 Small island
30 POTEXT.TFT LEVEL 1 Land place names
31 POTEXT.TFT LEVEL 2 Ocean place names
32 POTEXT.TFT LEVEL 3 Ice Status
33 POTEXT.TFT LEVEL 4 Land place names (diacri tical)
34 POTEXT.TFT LEVEL 5 Ocean Place names (diacr itical)
35 POTEXT.TFT LEVEL 6 Mountain names
36 POTEXT.TFT LEVEL 7 Mountain names (diacriti cal)
37 POTEXT.TFT LEVEL 8 Island names
38 POTEXT.TFT LEVEL 9 Island names (diacritica l)
39 POTEXT.TFT LEVEL 10 Desert names
40 POTEXT.TFT LEVEL 11 Desert names (diacritica l)
41 POTEXT.TFT SYMBOL 1 Black annotation
42 POTEXT.TFT SYMBOL 4 Blue annotation
You can build polygons from the line data within OzGIS in the usual way.
However, any polygons that are not complete (closed) will be dropped. This means that polgons around the edge of tiles disappear. In some cases there seems to be additional data which may help e.g. there is not only Coast lines but also coast closure lines.
Within the BROWSE library there is a feature code 9 which gives
boundary lines so extract line feature 9 as well as feature 2=coast.
You will find that you then get polgons for the whole rectangle
(-180,-90) to (180,90). You should however be able to edit the
output from OZDCW to throw away the type 9 records that are not
required (look for 90.0).
. select the library (BROWSE, SASAUS etc)
. OZDCW or VPFDUMP the file CAT. to find the directories / coverages
. OZDCW or VPFDUMP the file INT.VDT in the required directories to find the feature codes
. if tiled look at \TILEREF\FBR. and \TILEREF\TILEREF.AFT to find the tile directory . generate data and parameter files for importing into OzGIS with the OZDCW
program
TXT. and xxTEXT.TFT for test
END. and xxPOINT.PFT for points
EDG. and xxLINE.LFT for lines
The procedure should work for other databases.
One restriction is that only numeric feature codes are handled.
If you want to process databases that use text feature values
(e.g. the Digital Nautical Chart) you will have to set up the
pairs of files in the usual way, but the edit the .PRM file to
change all to text feature vales to numbers.
The OzGIS system was designed to accept data from external sources.
These data may be supplied in standard formats that are supported by the IMPORT option in the top menu. If not, data will have to be reformatted into one of the system formats before use.
Map objects are identified by 10 character keys e.g. PARIS, NEW
YORK, 12345 Where keys are generated within OzGIS they are usually
left aligned numbers.
Every type of file has a standard format within OzGIS.
The data files have been designed with a simple format which can be easily generated on computer systems. Most data are held as character files so that they can be generated by programs with, for example, database system export procedures, formatted FORTRAN write statements, or by a text editor. The record lengths are up to 80 bytes long.
Each file starts with a comment record of up to 80 characters, which should be used to hold a meaningful description of the file. The OzGIS system will display this comment when data files are interrogated, so it is in your interest to make the comments meaningful. This record must contain at least one non-blank character.
Data values are entered in record fields that are multiples of 10 bytes.
The following computer restrictions apply:
The maximum numbers of some data items that can be handled are
system parameters.
The formats for describing the data files in the following sections are similar.
The number of bytes in the field is given at the start of the line. If there are several values in a format, this condition is indicated differently (e.g. 8 x 10 implies eight fields of 10 bytes).
The information on the next line is the type of data in a field:
Attribute data are often obtained from Census Bureaux. These data are seldom what is required, so will need processing before use.
Data often need normalising to allow for the differences in zone sizes. This is done by arithmetic operations where new attributes are derived by dividing by total population, area etc.
Also, data often need amalgamation e.g. census age groups to get
the required group.
Attribute files contain the attribute value of each zone or line or site for a number of attributes. The names must correspond to those defined in a geographic file.
The attribute description is used by OzGIS as a heading in a map displaying the attribute. The units description is used by OzGIS as a heading to the class values in the map legend.
For efficient use of the system and to facilitate disc file management, files should contain as many attributes as possible (to avoid having separate files for each attribute).
Attribute files will usually be prepared by special programs which extract data from a data-base and convert attribute values into the OzGIS format.
Comment Record:
80 byte comment describing the data
Header Record:
10 integer number of attributes
10 integer number of names
10 real value used to indicate missing data
Name Records:
8 x 10 byte names, sorted into ascending order
Sets of records follow to define the attributes:-
Definition Record:
30 byte attribute description
10 byte units description
Values Records:
8 x 10 real attribute values for zones, lines or sites in name
order
DEMOATTR.DAT - ATTRIBUTES FOR SIMPLE 3 ZONE TEST MAP
5 6 -9.9
ABCDEFGHIJZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE Z
FIRST STATISTIC FIRST UNITS
1.0 2.0 3.0 4.0 5.0 6.0
SECOND STAT SECOND UNITS
100.0 200.0 -9.9 400.0 500.0 600.0
THIRD STAT 3RD UNITS
0.1 0.9 0.3 0.7 0.1 0.8
FOURTH STATS 4TH UNIT
1.0 2.0 3.0 3.0 2.5 1.5
FIFTH STAT 5TH UNIT
9.0 6.0 3.0 2.0 6.0 8.0
Many data retrieval systems (e.g. ORACLE,SAS) produce attribute data in a form where for each attribute the names and their values are given.
This tabular format is supported in OzGIS although there are some restrictions on its use. The list of names is obtained from the first attribute; hence no new names can occur in following attributes (although names may be missing). A set of data records for an attribute is assumed to finish (and the next set start) when the attribute description & units changes.
Comment record:
80 byte Comment describing the data
Data records:
10 byte name
10 real value
30 byte attribute description
10 byte attribute units
SIMPLE FORMAT ATTRIBUTE FILE - DEMOSASA.DAT
TOP 1.0 DESCRIPTION A UNITS A
SQUARE 2.0 DESCRIPTION A UNITS A
DIAMOND 3.0 DESCRIPTION A UNITS A
TRIANGLE 4.0 DESCRIPTION A UNITS A
TOP 1.0 DESCRIPTION B UNITS B
DIAMOND 3.0 DESCRIPTION B UNITS B
SQUARE 2.0 DESCRIPTION B UNITS B
TRIANGLE 4.0 DESCRIPTION B UNITS B
TOP 1.0 DESCRIPTION C UNITS C
SQUARE 2.0 DESCRIPTION C UNITS C
DIAMOND 3.0 DESCRIPTION C UNITS C
TRIANGLE 4.0 DESCRIPTION C UNITS C
TOP 1.0 DESCRIPTION D UNITS D
TRIANGLE 4.0 DESCRIPTION D UNITS D
DIAMOND 3.0 DESCRIPTION D UNITS D
DIAMOND 3.0 DESCRIPTION E UNITS E
TRIANGLE 4.0 DESCRIPTION E UNITS E
The WK1 file format is used to import/export data between OzGIS and spreadsheet and database systems. Refer to the chapter on the WK1 interface to systems.
Data from spreadsheets can be input in Lotus 1-2-3 format (WK1).
The spreadsheet must be set up in a fixed format:
The data values are in a matrix with the values for the zones (or sites or lines) in columns and the different attributes across in the rows.
Values can be missing and can be integer or floating point.
The first column must contain labels which are the 10 character zone (site etc) names, beginning at row 3. These must be SORTED in ascending order.
The top row contains labels that are the (up to) 30 character attribute descriptions starting at column 2.
The second row is the 10 character attribute descriptions. This is recommended but does not have to be present as some systems (e.g. MS ACCESS) do not allow units to be defined.
e.g. the file DEMO123.dat can be read into the spreadsheet. It should look like:
| GROWTH | SALES | |
| NUMBER | $ | |
| ABBOTSFORD | 7418 | 237 |
| BURWOOD | 9925 | 955 |
| CONCORD | 8984 | 202 |
| CROYDON | 9369 | 298 |
| CROYDON | W | 735 |
| FIVEDOCK | 9903 | 716 |
| HABERFIELD | 727 | |
| HOMEBUSH | 6631 | 704 |
| HUDSONPARK | 4668 | 71 |
| MORTLAKE | 1725 | 198 |
| STRATHFIELD | 6285 | 663 |
| YARALLA | 9875 | 516 |
For example, with Microsoft Excel for Windows, the test file can
be read by choosing the option "Open" from the "File"
menu and giving the test file as \OZDEMO\DEMO123.DAT. A spreadsheet
in the above format can be output by selecting the "Save
As" option from the "Files" menu and using the
WK1 format option.
Attribute data files for the Atlas mapping system come as pairs of files, a format file and a data file.
The first record of the format file is a map name, which is ignored. There follows a a set of records, each of which gives the name of an attribute. For example, the following file specifies two attributes:
" Bundesland$"
"Population 1984 Totale Population in Tausend"
"Ausdehnung in qkm Ausdehnung in Quadratkilometer"
The data files have one record for each map item. Each record starts with the item name, and is followed by the values. The values are in the same order as the attribute names and there is one per attribute (2 here). Values can be in integer, decimal point or exponential formats. A value of 1.0E36 is missing data. For example:
"SCHLES.-HOLSTEIN", 2615 , 157.21
"HAMBURG", 1.23E21 , 1.0E36
"BREMEN", 671 , 404
"NIEDERSACHSEN", 7230 , 47.447
"NORDR.-WESTFALEN", 16.777 , 34061
"HESSEN", 5548 , 21114
"RHEINLAND-PFALZ", 3627 , 198.48
"SAARLAND", 1052 , 25.71
"B.-WUERTTEMBERG", 9240 , 35751
"BAYERN", 10964 , 70552
"BERLIN", 1850 , 480
Names and attribute descriptions must be delimited by apostrophes as shown, and values must be comma delimited. Only the first 10 characters of a zone etc name is used and only the first 30 characters of a description.
Two data files have to be specified. The first is the format file, the second the Atlas data file. The format file is handled as a parameter file within the entry process so can be present on disk as a file named with extension .PRM. In practise your two files will probably have the Atlas standard file names with extensions FMT and DAT and you give the full file names when asked for them.
For example, you might have a pair of files named EUROPE.FMT and
EUROPE.DAT so you give the parameter file as EUROPE.FMT and the
data file as either EUROPE or EUROPE.DAT (as DAT is the default
extension).
The LAMM package was developed at the CSIRO Division of Building Research. The format is supported as it is the only suitable format for mapping available in the Australian Bureau of Statistics GEOSTATS system.
The first record gives the number of map items and the number of attributes respectively.
The attribute names follow, one per record
Finally the value records are given, being the name followed by the values.
The records are sorted into ascending name order. Values are separated by blanks or commas.
An example file is DEMOLAMM.DAT:
12,8
MALES 35 - 44 (81)
MALES 35 - 44 (86)
MALES - UNEMPLOYED (76)
MALES - UNEMPLOYED (81)
MALES - UNEMPLOYED (86)
INCOME MALES $18001-$26000 (76)
INCOME MALES $18001-$26000 (81)
INCOME MALES $18001-$26000 (86)
'ABBOTSFORD' 69 0 14 27 48 0 51 55
'BURWOOD E' 223 0 48 134 89 0 218 397
'CONCORD' 102 0 5 12 29 0 109 197
'CROYDON N' 161 0 27 50 53 0 156 284
'CROYDON W' 180 0 24 36 76 0 307 241
'FIVE DOCK' 50 0 20 2 0 0 19 11
'HABERFIELD' 126 0 28 20 20 0 208 185
'HOMEBUSH' 114 0 26 51 37 0 165 212
'HUDSONPARK' 243 0 65 99 65 0 231 385
'MORTLAKE' 0 0 0 0 2 0 0 113
'STRATHFIELD' 100 0 4 7 10 0 74 70
'YARALLA' 7 0 16 2 0 0 4 3
The comma delimited format consists of a set of records: Each record has a series of values separated by commas.
The first record gives the "column" names. The first is the map item names, and the others are the attribute descriptions.
The following records are the data:
The first value is the item (zone,line or site) name and there follows one number for each attribute.
The file DEMOCOMD.DAT looks like:
"ZONE","DOGS","CATS","BIRDS","RATS","FISH","HENS","SNAKES","COWS"
"Australia",1,0,0,0,36,40,0,400.123
"Europe",123.45,0,4,3,47,70,3,0
In many cases the best procedure is to read comma delimited formats
into your spreadsheet, convert them into a sensible format,
and output them in WK1 format as above.
The Community profile floppy disk software from the ABS generates
comma delimited files that are the same as the above comma delimted
format except for an extra (second) column that gives a description
for the Census regions. The software drops the extra column.
Other formats will be supported as required.
We will support any formats for major data suppliers, but you must send sample data and documentation.
We will also attempt to support file formats from other packages.
Text attribute files allow miscellaneous information to be attached to map items and accessed during map interrogation
The file format is:
The first record is an 80 character comment
Sets of records follow for each map item:
The item name (1-10 characters) preceded by $
Any number of lines of text (up to 80 characters long)
The $ indicates the start of a new item
An example file is DEMOTEXT.DAT
A file could look like:
SALES TERRITORY DEFINITIONS
$Terr 1
North West NSW
Fred Smith
1991 Target $200,000
$Terr 2
Central Queensland
Salley Jones
1991 Target $320,000
$Terr 3
Tasmania
The Big Bopper
1991 Target $10,000
The standard data format reflects the internal topological file structure.
In practice, a complete data file is seldom available. It is more
common to bring in just points (as a map and points partition)
or lines (as a map and segments partition). Zones are usually
formed from the segments by using the zone/polygon building process.
Coordinates are usually given either in degrees (for lat,long)
or in metres / feet for UTM.
Geographic files contain several partitions. The first must be the map partition, and can be followed by at most one of each of zones, polygons, lines, segments and points partitions.
Each partition is preceded by a type record, which is one of MAP, ZONES, POLYGONS, LINES or POINTS; for example, a zones file must have the following structure:
Comment record
MAP
map records
POLYGONS
polygon records
ZONES
zone records
SEGMENTS
segment records
Different partitions are present (the MAP partition is always first) according to the type of data:-
Files which describe zones have a ZONES partition to define the zones, a POLYGONS partion to give the polygons that bound each zone (including lakes and islands), and a SEGMENTS partition to define the coordinate points that draw the segments along the polygon boundaries.
Sites files have a POINTS partition to give the site names and locations.
Lines files have a LINES partition to define the line names and a SEGMENTS partion to define the coordinate points in the segments that make up the lines.
Line overlays are defined by SEGMENTS partitions.
Marker and name overlays are defined by POINTS partitions.
Coordinate data should be entered in standard units. Coordinate pairs are always in the order (X,Y) (e.g. (Longitude, Latitude)). Note that latitude must be entered as a negative number in the Southern Hemisphere.
Data entered in latitude-longitude projection can be converted to other projections.
Feature codes may be included to give a classification of geographic items. e.g. segments may be classified as different types of roads.
All geographic regions (windows) are given in actual coordinate
values in the order: X-minimum, X-maximum, Y-minimum, Y-maximum.
The geographic data are held internally as a word-addressable random access disk file.
The file structure reflects the data structure with the necessary indexing etc for processing.
Additional data are also generated for efficient processing:-
Comment Record
80 byte comment describing the data
Map Partition
This partition contains general information about the file (map) and must be the first partition.
Type Record:
3 byte partition header = MAP
Window Record:
4 x 10 real the region covered by the file
Projection Record: (now redundant)
10 integer Map projection code
0=none, 1=lat-long degrees
10 integer type of zones (optional)
10 integer tolerance for joining line segments endpoints into
polygons. Values range 0-3, usually zero
Used when endpoints calculated by spatial operations
e.g. polygon intersection, when arithmetic roundoff
can cause joining to fail
Zones Partition
This partition defines the zones in the geographic region.
Each zone is defined by one or more polygons. A zone may consist of a polygon, several separated polygons, polygons with interior polygons of other zones, etc.
If a zones partition is present, a polygons partition with the referenced must be given.
The partition may be used as a polygon underlay and feature codes may be used to give a classification e.g. the polygons may be different soil types.
Type Record:
5 byte partition header = ZONES
Definition Record:
10 integer number of zones
10 integer number of feature codes
Feature code Records (if required):
8 x 10 integer feature codes
Zone Records:
10 byte zone name, usually left justified, blank filled
10 integer number of polygons in the zone
Polygon Records:
8 x 10 integer identifying numbers of the polygons
Line Partition
The partition defines networks of lines (e.g. roads, rivers). Each network has a name and is specified in terms of line segments.The name can be used to apply quantised attribute data.
Type record:
5 byte partition Leader = LINES
Header record:
10 integer number of lines
Line record:
10 byte line name, usually left justified, blank filled
10 integer number of segments forming the line
Region Record:
4x10 real line limits (window)
X minimum, X-maximum, Y-minimum, Y-maximum)
Segments Records:
8x10 integer the identifying numbers of the line segments.
Polygons Partition
A polygon defines an enclosed geographic area. Each polygon is specified in terms of the line segments which constitute its boundary. If a zones partition is given, every polygon referenced by the zones must be defined.
The centroid or internal point of a polygon is be used by OzGIS to locate text (zone names) or graphic symbols; a points partition is generated.
Type Record:
8 byte partition header = POLYGONS
Header Record:
10 integer number of polygons
A set of records follow for each polygon:-
Definition Record:
10 integer polygon identification number
10 byte name of zone enclosed by polygon
10 integer number of lines forming the polygon boundary
10 integer level of polygon for display using
polygon fill 0=standard, 1=lakes, 2=islands in lakes etc. (range 0-5)
Region Record:
4 x 10 real polygon limits (window)
(X-minimum, X-maximum, Y-minimum, Y-maximum)
2 x 10 real centroid or labelling point (X,Y) in the polygon (set to centre of window if not given)
10 real area of polygon
(calculated if not given)
Segments Records:
8 x 10 integer the identifying numbers of the segments + ve if
segment is clockwise, -ve if anticlockwise.
Segments Partition
Line segments are defined by a set of points connected by straight lines.
Segments may define the boundaries of zones, define line networks, or line overlays.
When a segment is a boundary segment of a polygon, it can be the boundary of at most two polygons.
In other words, the polygons must be a unique tessellation of the geographic region.
When the segments define polygon boundaries, the partition should contain only the segments of the polygons, and the records must contain the names of the zones on each side. Left and right zones are defined by the direction implied by the sequence of points in the line. The zone names must correspond to those defined in the zones partition. The special zone name OUTSIDE (left aligned) should be used when the line is at the edge of the map, or on the boundary of void areas.
Line segments (of polygons) must be closed (i.e., the last point in a segment must be the first point of another segment), and segments must not cross or have loops. Further, segment must not be repeated.
Segments that are to be used as geographic overlays may have feature codes to give a classification e.g. different types of rivers.
Address information can be present. This consists of the name of the street followed by 0, 1 or 2 sets of entries for street number ranges and postal codes. These zip codes are optional as are the number ranges. If 2 ranges are given one is odd and the other even numbers. The start and end values are given according to the direction of the numbers and the digitising direction.
Type Record:
8 byte partition header = SEGMENTS
Header Record:
10 integer number of segments
A set of records follows for each segment.
Definition Record:
10 integer identifying number
10 byte name of left zone (if line is part of a zone boundary)
10 byte name of right zone (if line is part of a zone boundary)
10 integer number of points in segment
10 integer number of feature codes
10 byte non blank indicates that address info follows
10 byte name of line network, default set to ldent number
this is also the name for interrogation
Feature code Records (if required):
8 x 10 integer feature codes
Address Records (if required):
10 byte name of street, park etc
6 x 10 integer start number, end number, postal (ZIP) code, followed by optional second set
Point Records:
8 x 10 real (X,Y) coordinate pairs (4 per record)
Points Partitions
The partition contains a set of points or sites at which symbols can be overlayed on the map. The site name can be used to apply quantised attribute data or used to annotate the points.
Feature codes can define a classification for display as sites.
Type Record:
6 byte partition header = POINTS
Header Record:
10 integer number of points
Point Records:
10 real X-coordinate value
10 real Y-coordinate value
40 byte site name or annotation
10 integer number of feature codes
Feature code Records (if required):
8 x 10 integer feature codes
Note that only the first 10 characters are used for the site name.
Geographic data for zones (e.g. Census districts) are usually brought in as the line segments that form the boundaries of the zones. The boundary segments contain the (X,Y) vertices that make up the line and the names of the zones on each side of the line.
These data are usually entered via the IMPORT option in the top menu, then excessive vertices discarded (thinned) using PREPARE DATA FOR DISPLAY, and then the full zone / polygon/ line segment / centroids structure built using BUILD TOPOLOGY FROM LINES SEGMENTS to prepare for display.
For example, to extract ZIP code boundaries from USA TIGER files, the left and right ZIP codes are extracted from the records and formed into left aligned zone names, and the latitude / longitude vertices are also extracted. If the left and right zone names are the same the segments are internal to the zone and can be ignored.
The following illustrates the standard format used to enter such data. Note that the MAP partition is required but that the extent need not be given.
EXAMPLE ZONE BOUNDARY SEGMENTS THAT CAN BE BUILT INTO ZONES - DEMOZSEG.DAT
MAP
0.0 0.0 0.0 0.0
0
SEGMENTS
10
107ZONE 1 OUTSIDE 2
102.00 503.00 114.00 503.00
125ZONE 2 ZONE 1 2
102.00 503.00 110.00 513.00
143ZONE 1 ZONE 3 2
114.00 503.00 110.00 513.00
161ZONE 3 OUTSIDE 6
114.00 503.00 115.00 505.00 116.00 507.00 117.00 509.00
118.00 511.00 119.00 513.00
187ZONE 2 ZONE 3 2
110.00 513.00 119.00 513.00
205ZONE 2 OUTSIDE 4
119.00 513.00 114.00 518.00 109.00 517.00 104.00 516.00
227ZONE 2 OUTSIDE 2
104.00 516.00 110.00 513.00
245SURPLUS SURPLUS 2
119.00 513.00 122.00 506.00
263OUTSIDE ZONE 2 2
103.00 509.00 110.00 513.00
281OUTSIDE ZONE 2 2
Address information can be added to line segments. Note the non-blank
flag.
EXAMPLE SEGMENTS (ROADS) WITH ADDRESSES - DEMOADDR.DAT
MAP
0.0 0.0 0.0 0.0
0
SEGMENTS
10
107ZONE 1 OUTSIDE 2 ADDRESS
Great North Road
1 666 2600
102.00 503.00 114.00 503.00
12 ZONE 1 2 ADDRHERE
Molonglo Gorge
102.00 503.00 110.00 513.00
143ZONE 1 ZONE 3 2 address
Burra Street
1 99 6 140
114.00 503.00 110.00 513.00
161 6 address
Northbourne Ave
1 55 2602 20 66 2600
114.00 503.00 115.00 505.00 116.00 507.00 117.00 509.00
118.00 511.00 119.00 513.00
187ZONE 2 ZONE 3 2
110.00 513.00 119.00 513.00
205 4 address
Yass rd
1 99 2600
119.00 513.00 114.00 518.00 109.00 517.00 104.00 516.00
227ZONE 2 OUTSIDE 2
EPPING HWY
44 22 77 11
104.00 516.00 110.00 513.00
245SURPLUS SURPLUS 2 address
Hume Highway
1 99 2301 88 44 2304
119.00 513.00 122.00 506.00
263OUTSIDE ZONE 2 2 address
Mains Avenue
1 99 2600 6 140 2600
103.00 509.00 110.00 513.00
281OUTSIDE ZONE 2 2 address
Lover's Lane
33 11
The full topological geographic structure can be entered (although
in practice this is seldom available).
COMMENT LINE FOR TEST DATA - DEMOZONE.DAT
MAP
102.00 122.00 502.00 518.00
0
ZONES
3
ZONE 1 1
352
ZONE 2 2
377 402
ZONE 3 1
327
POLYGONS
4
327ZONE 3 3 0
110.00 119.00 503.00 513.00 114.00 510.00
187 -161 143
352ZONE 1 3 0
102.00 114.00 503.00 513.00 108.00 506.00
-125 107 143
377ZONE 2 3 0
102.00 110.00 503.00 513.00 104.00 508.00
-263 -281 125
402ZONE 2 3 0
104.00 119.00 513.00 518.00 110.00 515.00
205 227 187
SEGMENTS
10
107ZONE 1 OUTSIDE 2
102.00 503.00 114.00 503.00
125ZONE 2 ZONE 1 2
102.00 503.00 110.00 513.00
143ZONE 1 ZONE 3 2
114.00 503.00 110.00 513.00
161ZONE 3 OUTSIDE 6
114.00 503.00 115.00 505.00 116.00 507.00 117.00 509.00
118.00 511.00 119.00 513.00
187ZONE 2 ZONE 3 2
110.00 513.00 119.00 513.00
205ZONE 2 OUTSIDE 4
119.00 513.00 114.00 518.00 109.00 517.00 104.00 516.00
227ZONE 2 OUTSIDE 2
104.00 516.00 110.00 513.00
245SURPLUS SURPLUS 2
119.00 513.00 122.00 506.00
263OUTSIDE ZONE 2 2
103.00 509.00 110.00 513.00
281OUTSIDE ZONE 2 2
102.00 503.00 103.00 509.00
A lines structure is used for line data that is to be displayed for attribute data. Each line can be made up of several segments:
SAMPLE LINE NETWORK DATA DEMOLINES.DAT
MAP
103.50 121.50 503.50 517.50
0
LINES
4
ROAD 3 3
110.50 119.50 503.50 513.50
187 161 143
ROAD 1 2
103.50 114.50 503.50 513.50
125 107
ROAD 2 2
103.50 110.50 503.50 513.50
263 281
ROAD 4 2
104.50 119.50 513.50 517.50
205 227
SEGMENTS
9
107 2 0 ROAD 1
103.50 503.50 114.50 503.50
125 2 0 ROAD 1
103.50 503.50 110.50 513.50
143 2 0 ROAD 3
114.50 503.50 110.50 513.50
161 6 0 ROAD 3
114.50 503.50 115.50 505.50 116.50 507.50 117.50 509.50
118.50 511.50 119.50 513.50
187 2 0 ROAD 3
110.50 513.50 119.50 513.50
205 4 0 ROAD 4
119.50 513.50 114.50 517.50 109.50 517.50 104.50 516.50
227 2 0 ROAD 4
104.50 516.50 110.50 513.50
263 2 0 ROAD 2
103.50 509.50 110.50 513.50
281 2 0 ROAD 2
103.50 503.50 103.50 509.50
Points files just give the (X,Y) locations and a site name / label.
These files can be used with an attribute file for mapping site data or can be used to place sysmols or labels at locations (overlays).
COMMENT LINE FOR TEST DATA - DEMOPOINT.DAT
MAP
102.00 122.00 502.00 518.00
0
POINTS
3
114.0 503.0 PNT1
104.0 516.0 PNT2
Not implemented
Geographic data are often available in polygon format, and this data definition enables it to be used used with OzGIS.
The common line segments on the boundaries of adjacement polygons are effectively defined twice in polygon data; OzGIS assumes that they are exactly the same. The polygon boundary must not cross itself.
Each polygon has a name, which is the name of the zone to which it belongs.
Polygons may occur inside other polygons. Where the polygon is not part of a zone (e.g. a lake) it may be given the name OUTSIDE.
The level field defines lakes, islands within lakes etc. When maps are generated on devices using polygon fill the level gives the order of display so the polygons will overwrite correctly.
Comment record:
80 byte comment describing the data
Definition Record:
10 integer map projection code
10 integer zone type (optional)
Each polygon is defined by a set of records:
Polygon header:
10 byte zone name, usually left justified, blank filled or OUTSIDE if an internal polygon.
10 integer number of points in the line
10 real level of polygon for hardcopy generation using polygon fill 0=standard, 1=lakes, etc.
Centroid record:
2x10 real centroid or labelling point (X,Y) in polygon
Point records:
8x10 real (X,Y) coordinate pairs (4 per record) The last point
must be the same as the first.
The SAS system provides a crude polygon format for map data. The old format has been updated to allow for multiple polygons in zones and for data at several levels of resolution.
The polygons must be given in the correct order for display when there are polygons within other polygons.
The data consists of variable length records with the following fields:
field1: the zone name
field2: the polygon number within the zone (usually 1)
field3: the X value
field4: the Y value
For example, part of a file might be as follows, where zone 19 has 2 polygons
17 1 135.0198593289 -45.006152242
17 1 135.0214474499 -45.008039698
17 1 135.0234586746 -45.011447966
17 1 135.0232417881 -45.011781529
17 1 135.0146185011 -45.012796119
17 1 135.0149845481 -45.012392245
17 1 135.0148004219 -45.011233956
17 1 135.0155192316 -45.009236805
17 1 135.0140719935 -45.006661419
19 1 135.0200279355 -45.018230647
19 1 135.0211774409 -45.018684313
19 1 135.0218305141 -45.017554402
19 1 135.023555249 -45.017326832
19 1 135.024860993 -45.014845043
19 1 135.0251943022 -45.014588848
19 1 135.0192894787 -45.023670658
19 1 135.0179009587 -45.022158593
19 1 135.0182676911 -45.021624267
19 1 135.0180351585 -45.020997345
19 1 135.0192095339 -45.020121485
19 1 135.0194375813 -45.01857923
19 2 135.0279172212 -45.023049563
19 2 135.0281361789 -45.022784472
19 2 135.0283748209 -45.0230802
19 2 135.0285159498 -45.022607252
19 2 135.0283438861 -45.023600549
21 1 135.041364044 -45.0087376237
21 1 135.039871216 -45.0095451251
21 1 135.039485425 -45.0093839765
21 1 135.037185282 -45.0106722265
.
.
.
.
.
Simple format files are in common use by the SAS system and other packages providing SAS interfaces. Polygon for lakes etc. should follow standard polygons to provide the correct display order for overwriting.
This format has now been updated in the SAS system.
Each data record has the form
10 byte zone name
10 real X coordinate
10 real Y coordinate
10 integer Polygon number within zone
SQUARE 3.0 5.0
SQUARE 7.0 5.0
SQUARE 7.0 10.0
SQUARE 3.0 10.0
DIAMOND 8.0 8.0
DIAMOND 10.0 5.0
DIAMOND 12.0 8.0
DIAMOND 10.0 11.0
TRIANGLE 13.0 5.0
TRIANGLE 16.0 10.0
TRIANGLE 19.0 5.0
TRIANGLE 13.0 2.0 2
TRIANGLE 15.0 2.0 2
TRIANGLE 14.0 4.0 2
SQUARE 4.0 0.0 2
SQUARE 8.0 0.0 2
SQUARE 8.0 4.0 2
SQUARE 4.0 4.0 2
SQUARE 0.0 0.0 2
SQUARE 5.0 1.0 2
SQUARE 5.0 3.0 2
SQUARE 7.0 3.0 2
SQUARE 7.0 1.0 2
OUTSIDE 15.0 6.0 2
OUTSIDE 15.0 7.0 2
OUTSIDE 17.0 7.0 2
OUTSIDE 17.0 6.0 2
TOP 4.0 8.0
TOP 19.0 8.0
TOP 19.0 9.0
TOP 4.0 9.0
This format is supported, but has not had much use. The data are primarily 2 point segments, so is inefficient on storage.
Note that only 499 2 point segments can be handled.
The data are usually passed through BUILD ZONES?POLYGONS to build polygons and then through PREPARE DATA FOR DISPLAY to join up the segments into ones of decent length.
The data are long Ascii records, and look something like:
XX91609160012583 1
MANUEL ST 8 8 201 299 200
29891600000011 14502 1450219711197119160 38 440195019510003016 234
10003016 213 1818 396750 757476396740
7574760610215040685606098370406849
MANUEL ST 8 8 301 359 300
35891600000029 14502 1450219711197119160 44 480195019510003016 233
10003016 212 1818 396740 757476396730
7574760609837040684906095020406848
MANUEL ST 8 8 361 399 360
39891600000037 14502 1450219711197119160 48 540195019510003016 233
10003016 233 1818 396730 757476396718
7574760609502040684806090470406846
SCHOOL ST 9 9 900 998 901
99991600000045 162 162 19720197209160 37 220200020010003031 107
10003031 108 1818 396611 755737396619
7557430605026045580006053140455632
SCHOOL ST 9 9 1000 1098 1001
109991600000052 162 162 19720197209160 22 140200020010003031 115
10003031 115 1818 396619 755743396624
7557460605314045563206054910455542
The DLG-3 format is the major interchange format in use, and data can be obtained from many mapping agencies e.g. from USGS.
The data differs in concept from the usual data displayed by OzGIS in that it is preclassified by the assignment of numeric "feature codes".
All identifiers are numbers. These are converted to names by left aligning them in the 10 character name fields.
The data entry process processed the lines only. Any line with one vertice or two vertices and the same node numbers is taken as a point.
Other lines are output with the left and right names set to the area names. Left and right area numbers of zero or one are taken to be outside the map.
Feature codes are stored as numbers (combined input pairs) for lines, points and zones e.g. '291 22' becomes 2910022.
The first area is ignored as it should be the boundary of the map.
Polygons are generated by passing the geographic file through the zone building process. This carries the area feature codes through to the polygons, retains the line segments, and forms a points segment that contains the centroids of the polygons.
Note that file should have 80 character fixed length records. In practise files often have no end-of-records (e.g. USGS CD-ROM files) or records may be truncated. Records with end-of-line markers must no be more than 80 characters long. Zero length records are not allowed.
You will find that DLG-3 files off ARC-INFO systems often have extraneous background polygons that "zap" the map when displayed.
Some test files are supplied for Hawaii. These were read off the USGS GeoDATA CD ROM on a SUN system, and 'newline' characters inserted to form 80 character records. The files had to be edited as an arbitrary polygon was given as outside the map as the left and right areas on the line (this could also be handled during display by specifying feature codes).
The test files are:
The data format is described in the US Geological Survey Circular 895-c "USGS Digital Cartographic Data Standards, Digital Line Graphs"
The files look like:
USGS-NMD DLG DATA - CHARACTER FORMAT - 09-29-82 VERSION s21_wb.dlg
HAWAIIAN ISLANDS POLY 10 DROPPED 1967, 1980 2000000.
this record not used, cant be zero length
3 3 9999 2 0.50800000000D+02 4 0 4 1
0.637820640000000D+07 0.676865799729109D-02 0.800000000000000D+07
0.180000000000000D+08 -0.157000000000000D+09 0.300000000000000D+07
0.0 0.0 0.0
0.0 0.0 0.0
0.0 0.0 0.0
0.10000000000D+01 0.0 0.0 0.0
SW 19.000000 -160.000000 -316386.41 1771715.66
NW 22.000000 -160.000000 -312489.03 2102112.53
NE 22.000000 -155.000000 208312.61 2101093.98
SE 19.000000 -155.000000 210917.63 1770684.40
WATER BODIES 0 74 74 010 12 12 010 70 70 1
N 1 -316386.41 1771715.66 0 0 0
N 2 -312489.03 2102112.53 0 0 0
N 3 208312.61 2101093.98 0 0 0
N 4 210917.63 1770684.40 0 0 0
.
.
.
.
N 74 -320966.08 2105481.92 2 0 0
-69 70
A 1 -68438.87 1949336.24 3 0 1 0 0
8 9 7
0 0
A 2 -327997.34 2094827.63 3 0 1 0 0
-10 -2 -1
40 150
.
.
.
.
A 13 -91708.84 2025480.45 3 0 1 0 0
-66 -65 -67
40 150
L 1 7 6 2 0 24 1 0
-332906.23 2078428.77 -332805.62 2077920.57 -331991.53 2078579.38
-332446.45 2079748.67 -331479.96 2080407.19 -331224.96 2080914.69
-331578.38 2082032.98 -331221.19 2082845.09 -330100.11 2084620.90
-329235.22 2085279.61 -328573.03 2086192.72 -328571.24 2087107.12
-327247.56 2088577.74 -325977.26 2088727.66 -325164.16 2088878.47
-324909.37 2089284.37 -324503.57 2088978.78 -323182.17 2089280.99
-322319.07 2089025.30 -321707.68 2089938.51 -321250.68 2089836.02
-320995.88 2090241.92 -319775.79 2090696.74 -318961.20 2091609.55
290 4000
.
.
.
.
L 70 74 66 11 0 2 1 0
-320966.08 2105481.92 -321422.78 2105736.82
290 4002
The standard interchange format for GeoVision GIS is Gina.
Only some of the data file is processed. Feature codes must be numeric. Zone names generated are of the form ZONE12345 and site names are of the form POINT12345.
Only boundary lines and points are output - you have to generate the zones / polygons afterwards.
The sample file DEMOGINA.DAT is as follows:
udb-start b v 8192
udb-header 0.5 fred-db "Fred's test database"
descr 29oct85 14:32:10 example GINA files
coord-sys rect feet
extent -12000, -8000, 12000, 8000
layer 1 base "base information layer"
layer 2 roads "roads and streets layer"
layer 3 hydro "hydrographic layer (rivers, streams etc)"
layer 4 telephone "telephone plant layer"
layer 5 lots "property lots layer"
network 1 emergency l 2 "emergency routes"
network 2 property p 5 "property polygon network"
udb-primary
table road free
field name char 40 i n "road name"
field r_type char 12 i n "type of road, arterial, highway etc"
field lanes num 2,0 "maximum number of lanes"
field surface char 10 n "type of surface"
fc 1000, 1099
table house free
field h_type char 10 n "house type: bungalow;""test quotes"" etc"
field lot_no num 10 i "lot number"
fc 1130, 1139
table lots free
field lot_no num 10 i u n "lot number"
field address_no num 6,0 i n
field street char 40 n "street name"
fc 1100
udb-feature
feat 1 1002 2 0 l xy 0 0 0 1 0
coor 1805 1120 1805 1143
coor 2018 1143 2018 1204 2508 1204
text "Elm Street"
attr Elm suburban 2 "asphalt"
feat 2 1004 2 0 l xy 0 0 0 1 0
coor 2508 1204 2508 820
text "Oak Street"
attr Oak arterial 4 "concrete"
feat 3 1400 5 2 l xy
coor 2508 903 2508 933
feat 4 1400 5 2 l xy
coor 2508 933 2568 933
feat 5 1400 5 2 l xy
coor 2568 933 2568 903
feat 6 1400 5 2 l xy
coor 2508 903 2568 903
feat 7 1400 5 2 l xy
coor 2508 873 2508 903
feat 8 1400 5 2 l xy
coor 2568 903 2568 873
feat 9 1400 5 2 l xy
coor 2508 873 2568 873
feat 20 1100 5 2 p xy
coor 2520 920
attr 10875, 104 Oak
feat 21 1133 5 0 l xy
coor 2530 920
attr 2-story 10875
feat 22 1100 5 2 p xy
coor 2520 890
attr 10874, 106 Oak
feat 23 1133 5 0 l xy
coor 2530 890
attr bungalow 10874
udb-polygon
poly 3 20 r e
poly 4 20 r e
poly 6 20 l e
poly 5 20 r e
poly 6 22 r e
poly 8 22 r e
poly 9 22 l e
poly 7 22 r e
udb-indirect
table road_types free
field r_type char 12 i u n "road type"
field maint char 2 "maintenance class"
field resp_code char 3 n "responsibility code"
attr highway m3 A-4
attr aterial m6 B-3
attr secondary n2 B-1
attr suburban s4 B-8
udb-indirect
table house_types free
field h_type char 10 i u n "house types"
field tax_code char 4 n "taxation code"
attr bungalow 10-5
attr 2-story 12-2
attr split 11-5
udb-end
SIF format will be supported if there is a demand.
Data files appear to be 80 character ascii files.
The files contain a series of commands that define how the coordinates are to be displayed.
Most of the commands are ignored.
The commands of value seem to be:
DID/ is the first record in the file, and gives some basic information. The
parameter MO=2 or MO=3 gives the number of dimensions (compulsory?). Any Z value is ignored.
OVR/ defines the active level. This is stored in the relations as a number column 'ovr' as it seems to be effectively a layer.
ASC/ggnum defines the graphic group number, and is used to form the entid of form SIFggnum.
If ggnum is 0 the item is ignored (not appended).
If ggnum is <0 a number is assigned to it (sequentially starting at 10001).
LST/xx, defines a line. There are 2-101 vertices in a record. If a record has 101 values and the next record starts with the same point as the end point it is taken to be a continuation. (actually found some records with more than 101)
LST/ and LST/OP are line strings.
LST/HO and LST/SO are polygons (solid & holes)
Vertices are (x,y) or (x,y,z) according to the DID/ header.
New records that are not continuations are taken to be new components.
Digitised map data can be entered into OzGIS in the AutoCAD Drawing Interchange and File format as lines, points and polygons.
The format is described in the AutoCAD manuals.
If the data are to be used for choropleth mapping (with attribute data) the entities must have been digitised with handles to give the entities names. The hexadecimal handle values will become the zone (or point) names that will also have to be used in the attribute files. You can rename the entities with a combine file by using the data reparation process, but the the easiest method is to edit the names with a word-processor. The names are treated as text. The handles are given in type 5 groups.
The entities are processed as follows:
LINEs are stored as line segments, and can only be used for line overlays as there is no left & right zone names to enable polygons to be built.
POINTs are stored as points. Any handle will be used as the name.
POLYLINE & VERTEXes give a series of points that are either lines for line overlays, or polygons if a bit flag values defines it as closed. If a handle value is given it becomes the name and attribute values can be linked to it (polygons).
TEXT entities are stored as points with the text group used as
the name or for assigning attribute values (first 10 characters).
The Digital Chart of the World is a 1.7 GB digital geographic database that is available on CD-ROM. Like most US government data it is public domain, price about US$200!
More than 200 different types of attributes present worldwide are logically organized into 17 thematic layers. Since each thematic layer may contain information in the form of points, lines, and/or polygons, there are up to 27 possible coverages present. In addition to the attribute information most layers contain one or more levels of annotation. Most of the annotation contains place name information for cities, mountains, lakes, or other geographic features. Other types of annotation supplement attribute coding or contain data quality information. The original text size and location information are retained, thus allowing the production of publication quality maps. The major thematic layers in the DCW database include international boundaries, hydrography, elevation, populated places, roads, railroads, utility lines, airports, cultural landmarks, physiography, supplemental data, and data quality.
The Digital Chart of the World was input from 1:1,000,000 Operational Navigation Charts and 1:2,000,000 Joint Navigation Charts. It includes 17 layers, aeronautical info, data quality info, drainage, supplemental drainage, hypsography, hypsography supplemental, land cover, ocean features, physiography, political/ocean, populated places, railroads, transportation structure, utilities, and vegetation.
The data comes on 4 CD-ROMs and includes a BROWSE database for superficial views of the whole world, and 4 detailed databases.
The detailed databases are split into 5 degree square tiles.
Ponts, lines and text data can be imported as DCW files. Lines can be built into polygons with some restrictions.
A CD-ROM drive does not have to be on-line; files can be copied from another PC.
Refer to the complete chapter on DCW processing.
Vector overlay files from the IDRISI raster GIS system can be entered. The files have a simple format of the form ident,number vertices
X,Y
. .
. .
X,Y
Where a 0,0 record indicates end of data
Points, lines or polygons can be entered.
Only records with one vertice will be processed for points, with more than one vertice for lines, and more than two vertices for polygons.
Three sample files are supplied for deaths during the 1854 London Cholera outbreak. These are STREET.VEC, DEATH.VEC and PUMP.VEC. See the associated *.DVC documentation files for details.
From NCGIA, Santa Barbara. Digitized in 1992 by Rusty Dodson from the map included in the book by John Snow: "Snow on Cholera...", London: Oxford University Press, 1936.
A trivial two line file could be:
1 2
16.7380009 18.6959991
17.6599998 18.7119999
36 3
11.3450403 4.9679508
11.0809002 4.4880772
11.6251144 3.5709989
0 0
Digitised boundary data can often be purchased in a format supported by the Atlas PC mapping system. The files are Ascii, and records are of the form:
"name",n,x1,y1,...........Xn,Yn
where
n=1 => a point
n=2 => a circle
n>2 => a polygon
n<0 => a line
These data can be entered via the OzGIS system with some restrictions:
An example file AFRICA.DAT may be included with your system:
"Morocco",141
13.92683,60.72203
13.92685,60.67901
13.99129,60.48547
14.1201,60.33495
14.24891,60.18444 A POLYGON
14.3777,60.07695
14.48501,60.05548
14.61376,60.07703
14.72104,60.09858
14.80687,60.14163
.
.
"Tunisia",113 A ZONE with 2 polygons
24.03397,61.15581
. . polygon 1
. .
24.03397,61.15581
25.49409,58.66141
. . polygon 2
. .
25.49409,58.66141
24.03397,61.15581 < - first point repeated after every polygon
.
.
"Mbabane",1
41.41317,7.313157
"Maseru",1
38.45704,4.957369 POINTS
"Pretoria",1
39.15494,8.036585
.
.
.
"euro3",-41
33.15051,61.9
33.10709,61.72918
33.14988,61.68601 A LINE
33.21407,61.62125
33.34267,61.55629
.
.
.
Atlas seems to handle multiple polygons within a zone by simply putting them all together in the record following the name i.e. if the first vertex is found to be equal to another in the following list, then that is the end of that polygon and the next vertex is the start of the next polygon etc. For some strange reason the first point of the region is repeated after each of the polygons.
Atlas does not support topologically structured polygons, so ensure that internal polygons are given after the containing polygons so they are not overwritten on the screen. Also, internal polygons that are to have the background colour should have names "OUTSIDE".
Apparently there are two possibilities for regions with multiple polygons: The polygons can be kept together, which results in the format which you see in the africa-files (see below). This is the default! The other possibility is to split the the region into separate polygons. This results in an export format where each polygon starts with the boundary name, number of vertices and then the vertices. (The easiest way to do this in ATLAS is to SELECT ALL, and then BOUNDARY, SPLIT, ISLANDS.)
The following is supposed to be from the ATLAS EXPORT/IMPORT MANUAL:
ISLANDS AND LAKES
The Island/Lake Rule
If you return to the first coordinate pair in the description of a region, you have closed the main polygon. The line to the next coordinate pair will not be drawn, but will instead signal the start of an island or lake. The last coordinate pair in the island or lake must be the same as the first one; this must also be followed by the first coordinate pair of the main polygon - this line again will not be drawn. This rule may be applied as many times in succession as necessary, one time for each island or lake. Curves created with Atlas*Draw can also have islands, but ASCII boundary files do not support this.
General Region Structure With Island/Lake
The format for a region containing an island and/or lake is:
"Pname","Sname",numxy
x1,y1
..
xn,yn
x1,y1
xx1,yy1,
..
xx1,yy1
x1,y1
The second xx1,yy1 pair closes the island or lake and is immediately followed by an x1,y1 pair, which closes back to the main polygon. Additional islands or lakes can follow, as long as each closes on itself and then closes back to the main polygon. The illustrations below show examples of a region with an island, and of a region with a lake containing an embedded region. The region with an island is listed as:
"Region w/Island",11
1,1 first coordinate pair
1,0
0,0
0,1
1,1 end of main polygon
2,1 start of island
3,1
3,0
2,0
2,1 end of island
1,1 end of main polygon
An entry for a region with a lake containing an embedded region:
"Region w/lake",11
0,3 first coordinate pair
3,3
3,0
0,0
0,3 end of main polygon
1,2 start of lake
1,1
2,1
2,2
1,2 end of lake
0,3 end of main polygon
"Embedded Region", 5
1,2
2,2
2,1
1,1
1,2
According to the documentation, regions with multiple polygons can name them all with a record of the form e.g. "poly1","poly2","poly3",num
The data we have seen does not seem to do this, but just gives
one name.
Many data suppliers can provide geographic data in a format suitable for use with the MapInfo mapping system.
This format is partially supported, primarily for Census boundaries. The main restriction is that the more contrived spatial types are not supported.
The data is supplied usually as two files. The MapInfo Interchange File (MIF) contains the coordinates. The other file, the MID file, contains data, of which the only part of interest is the names of the spatial objects. Hence the MID file has to be given if you want to display attribute data, such as Census data, according to the names. Optionally the MID file need not be given, in which case the lines, points and polygons can only be used as overlays.
The MIF file starts with a header of the form:
Version 2
Delimiter ","
CoordSys Earth Projection 1, 0
Columns 2
Name Char(40)
ID Integer
Data
The only parts of the header used are:
"Delimiter" defines the seperator used in the MID file, default <tab>
"Columns" gives the number of values in the MID file for each object
"Data" indicates the end of the header and start of the coordinates etc
The data part of the file describes several types of objects. Only real geographic types are processed:
POINT and CENTER describe points (sites)
LINE and PLINE describe line segments
REGION describes zones (polygons)
Entries such as PEN are ignored.
A typical Census boundary file will have region entries with coordinates that will be output as polygons and centre's output as points. The polygons and the points will both have the same names from the MID file, so Census data can be mapped as either zones or sites, and the polygons and points can also be used for overlays e.g. to put names on the polygons.
For example, the data part of a MID file could look like:
Region 1
41
147.30982 -42.851953
147.309298 -42.851559
147.309174 -42.851233
147.309033 -42.851096
147.308207 -42.851211
. .
. .
. .
. .
. .
. .
147.312079 -42.850697
147.310575 -42.851964
147.30982 -42.851953
Pen (1,2,12582912)
Brush (2,16777215,16777215)
Center 147.308418 -42.848512
Region 1
13
147.286268 -42.838088
147.282985 -42.841294
147.283788 -42.842113
147.285434 -42.843622
147.286394 -42.844522
147.28709 -42.845175
147.289192 -42.847147
147.290486 -42.84662
. .
. .
. .
. .
The MID file provides the names of the objects as "columns". You will have to provide the number of the column that is the names (usually 1)
If a polygon is inside another it should have the name "OUTSIDE" so it will be displayed with the background colour.
A MID file with the name in column 1 looks like:
Canberra,637
Burra Creek,639
Phred,640
London,641
Wagga Wagga,642
1230807,644
.
.
Names files give lists of zones, lines or sites which are to be used to restrict certain kinds of processing in OzGIS.
The file would usually be prepared with a text editor, possibly operating on a file output from OzGIS.
Comment Record:
80 byte comment describing the data
Name Records (one per zone or line or site)
10 byte name
DEMONAMES.DAT - NAMES FILE
ZONE 1
ZONE 2
ZONE 4
Combine files define new map zones in terms of zones in a base map, or site catchments in terms of percentages of base zones.
Comment record:
80 byte comment describing the file
Header record:
10 integer number of items defined
Sets of records follow for the items:
Item definition record:
10 byte name (ascending order)
10 integer number of zones
Zone records:
10 byte zone name (ascending order)
10 real proportion of zone in area (0 to 1.0)
This file defines three territories AREA1, AREA2, AREA3 in terms of base zones A, B, ......
3 AREAS
3TEST AREAS
AREA1 1
H 1.0
AREA2 3
N 1.0
O 1.0
R 1.0
AREA3 5
A 1.0
B 1.0
C 1.0
D 1.0
E 1.0
Device files describe the characteristics of graphics display devices and set colours etc.
Standard files are usually held on the system for all devices available. Users would not usually define their own.
OzGIS was designed to operate as a highly interactive colour mapping system where speed of display was obtained by the use of an advanced raster display system. The software can operate on most graphics devices, but there could be loss of speed and capabilities depending on the characteristics of the devices being used.
OzGIS is based on graphics packages with the functionality of the GKS graphic standard. These graphic packages provide graphic primitives such as lines, text, and filled polygons. An important feature of GKS is that it is device independent so the package allows OzGIS to produce maps on a large range of devices.
Every device available for use with OzGIS has at least one file associated with it.
All devices within OzGIS have the same characteristics so e.g. a map previewed on a display device can be output directly to a hard-copy device. The files ensure that a device with limited capabilities can simulate the required capabilities in the best way.
The device files also set GKS primitive attributes such as colours and zone fill types. A colour display system has several files available that provide standard sets of colours for maps.
The easiest way to generate device data files is to edit standard ones.
The device files require colours to be specified in blue,green,red. One way to decide on these values is to look at the definitions in the colour names data file \ozgis\x11-bgr.dat.
When outputting to a printer under WINDOWS you will find that
you need a device file with a white background. Also, some printer
drivers only show text that is black or white. The background
is always assumed to be just the paper i.e. it is not coloured.
Comment record:
80 byte Device description
Size record:
10 real Extent of device surface
Note: defines units used for all sizes in data i.e. divide by this
10 real width of device in device units (now set from OZGIS.INI)
10 real max address height of device (now set from OZGIS.INI)
Type record:
10 integer GKS workstation number
10 integer Display type, 1 = raster display, pixel addressed
2 = continuous coordinates
10 integer Fill type, 1 = solid colour
2 = pattern
3 = device hatching
4 = OzGIS hatching for OzMAP etc
5 = colour simulation for 4 pen plotter
10 integer Locator device number, 0 = none, 1 = default
2 = crosshairs
Advanced Raster Record (now set fromOZGIS.INI)
10 integer number of bit planes (1-24)
10 integer length of LUT (1-4096)
10 integer number of pixels across screen (256-4096)
10 integer number of lines on screen (256-4096)
10 integer run-length encoding/decoding, 0 = not available
Colour definition record:
10 integer number of colours defined (162)
Colour table records:
10 real blue value (0.0 - 1.0) for colour table
10 real green
10 real red
The rest of the data records set internal tables for GKS primitive
attributes. Most records reference the colour table; the index has range 1
to length of table.
Area Fill records:
10 integer colour index
10 integer fill or style index
Several fill records are required, in following order:
background. NOTE also the menu / messages/ everything colour
zone missing data
excluded zones
diagram background
line or site quantisation legend and diagram
8 polygon underlay records
Text records:
10 integer colour index
10 integer font number (1-9) as defined in OZGIS.INI
10 integer text precision 0=STRING, 1=CHAR, 2=STROKE
10 real height of character space (pixels)
10 real width of character space (pixels)
Fonts are available for use on the screen, but are more usually used for output
on plotters.
The text records are:
4 records to define the text available for name overlays at sites or typed in text.
The text is usually defined in increasing size order.
Legend text record: This is fixed size text used for generation of all the legends. The size is very important as it governs the overall size of the legend e.g. the zone legend boxes are 3 times the text height in height, 2 times the text width in width.
Attribute description text record: This is normally large text. The interactive system has to be able to clear it off for each attribute so it should be fixed size hardware text in that case. When two variates are displayed the two descriptions are separated by a 'VS' or 'AND' generated using the legend text.
Line records:
10 integer colour index
10 integer GKS type (1-4)
1 = solid, 2 = dashed, 3 = dotted, 4 = dash dot
The actual records are as follows:
4 records for lines to be used for line overlays.
4 records for lines to be used for quantised lines (line-type has no meaning here as types are assigned according to quantisation).
A record to define zone boundaries line.
A record to define the line used to draw axes on diagrams (should be solid).
A record to define the line used to draw statistical values on diagrams.
Marker records:
10 integer colour index
10 marker ident (number in marker font see OZGIS.INI
10 real marker height (and width)
The records are as follows:
4 records for markers to be used as overlays at sites.
4 records for markers used for sites with quantised attribute data (marker size has no meaning, is set for class).
1 record for site marker background (currently not used)
1 record for scatter diagram (GKS marker no 1)
Colour Sequence records (170 records):
10 integer colour index
10 integer style index
These records give sequences of colours for colouring zones after quantisation.
There are two types of sequence:
The class fill is found by sampling out of the sequence for the number of classes, e.g. for bivariate
2 classes 1 7
3 classes 1 4 7
4 classes 1 3 5 7
Similarly, the single variate 121 value array allows exact sampling
for number of classes 2-7; a best choice is made for 8,9 or 10
classes. In the special case of pseudo-continuous colour maps
the whole 121 values are used.
The US Census Bureau supplies data on CD-ROM. There are two types supported:
1. the population and housing Census data (STF1A files), one State per CD-ROM
2. the digitised map data (TIGER format) supplied as one County per CD-ROM
The data entry process provides the facilities to input these data, BUT...
THE FILES MUST BE NAMED IN THE CORRECT WAY as described later.
The CD-ROM files can be very large, but the internal OzGIS files are much smaller. Hence the usual procedure will be to read the raw data files directly off CD-ROM. Processing can take some time.
The basic facility provided in the OzGIS system is to map tract/BNA or block group level data on a County basis. Census data can be extracted into one attribute file for one or more Counties. Census boundaries can be extracted into separate files for each county. Multiple county maps are generated by mapping the single attribute file with multiple geographic files.
Data for map overlays (e.g. roads) can also be extracted from TIGER data.
These data can be displayed without Census data.
Other data could be extracted from the CD-ROMs (e.g. blocks, places) and will be supported if there is demand. The capacity of the OzGIS system can be exceeded by these data..
The capacity should be sufficient to produce tract/BNA maps with overlays for single counties in all cases.
Generally the procedure for producing tract/BNA maps is to enter the TIGER data for the county of interest and all the STF1A files for the same county by selecting the appropriate options from the data entry menus.
Usually a new DOS directory will be set up for each map area. It must be on the same disk as the \OZGIS directory.
Census data is often not exactly what is required, PREPARE DATA FOR DISPLAY
will probably be used to produce derived attributes. Common processing is to
amalgamate age ranges and to normalise by dividing by total population.
The boundary line segments will probably be thinned to reduce
their size and speed up display by using the PREPARE DATA FOR DISPLAY option.
The BUILD TOPOLOGY option has to be used to form the polygons from the
TIGER lines data.
Finally the data are mapped with SIMPLE CENSUS-TYPE mapping of INTERACTIVE
DISPLAY AND ANALYSIS options.
The most important sections in this appendix are:
Processing STF1A data and
OzGIS Processing of TIGER data
These sections follow, with an example and further more general information
after that.
Extensive documentation is available from the Census Bureau and on the
CD-ROMs.
Some of that documentation is reproduced here.
You enter TIGER data into OzGIS with the data entry process.
Select IMPORT GEOGRAPHIC FILES from the top menu and then
IMPORT A TIGER FORMAT GEOGRAPHIC FILE
The next menu is:
TRACTS / BNA
BLOCK GROUPS
BLOCKS
ZIP CODES (IF PRESENT)
VOTING DISTRICTS
SELECT LANDMARKS BY FEATURE CODES
SELECT LINES BY FEATURE CODES
SELECT POINTS BY FEATURE CODES
You will probably use options TRACTS / BNA and BLOCK GROUPS to extract
boundaries for mapping with STF1A data. The build process has to be used
to build the polygons.
The option SELECT LINES BY FEATURE CODES will also be used often to extract
line overlay data such as roads.
The Feature codes are described later in this appendix.
The TIGER files must be present on hard disk or CD-ROM with file names in a
restricted form.
It seems that each state is on at least one CD-ROM (some states like California
are on two or more, but most are either on one by themselves or share
a disk with one or two small states). The structure of the CD-ROM appears
to be: general documentation and full state FIPS listing files at
the top (GRF_N_xx, where xx is the state's FIPS code); a subdirectory
for each state named by its FIPS code (e.g. Indiana's subdirectory is 18); in
each state's subdir are subdirectories for each county, again by FIPS codes
(e.g. Allen County, Indiana is 003) using 3 digits; in each of these reside the
(finally!) Tiger files of the form TGRXXYYY.F4n, where XX is the STATE code and
YYY is the county code and n is the record format code.
You usually read data directly off CD-ROM by giving the full file name.
The files will probably already be named correctly on CD-ROM, where they usually
to have extensions of the form ".F4n". e.g. e:/36/121/tgr36121.f41
You give the name of any one of the files and that name is used as a
template for the rest of the files.
There are two forms of file name:
Firstly, as files are often on CD-ROM with file names of the form, for
example boondocks.f41, boondocks.f42, boondocks.f43 etc, the data entry
process will look for sets of files with names of the form ????.f4n
If no files are present of this form it will look for a second form, where
the file names must contain the string "TGRn" where n is 1,2,3 or 7. This
ensures that related files are named as a set. Files on hard disk are usually
given names with extension ".DAT".
Name examples on hard disk are WASHTGR1.DAT, WASHTGR2.DAT, WASHTGR3.DAT,
WASHTGR7.DAT and TGR1NY.DAT and TGR2NY.DAT
Only the files of the required types are required:
Extracting Census boundaries usually requires types 1 and 2, but in some
cases the zone names (e.g. voting districts or 1980 regions) require that
the record type 3 file is also processed.
Extracting lines by feature code requires types 1 and 2.
Extracting points by feature codes requires type 1.
Extracting landmark features by feature code requires type 7.
Address extraction by feature code requires types 1 and 2. Type 6 records
are not processed.
US Census data STF1A files can be entered into the system with the entry
process by choosing IMPORT ATTRIBUTE FILES from the menu and then
one of:
IMPORT USA CENSUS STF 1A FILES FOR TRACT/BNA
IMPORT USA CENSUS STF 1A FILES FOR BLOCK GROUPS
The data files must be present with names of the form *1An* where n is in
the range 0 to 9. The supplied files on CD-ROM will probably have extensions
DBF and file names in the correct form. Data files on hard disk are usually
given the extension .DAT
Example file names are e:/xyz/stf1a0dc.dbf, stf1a0in.dat, wash1a3.dat
You do not need to give the file extension if it is the default .DAT
All files present will be processed, so anywhere between 1 and 10 files
will be read. It takes a long time to read all the data, but it will be
usual to load it all in once.
You give the name of any one of the files and that name is used as a
template for the rest of the file names.
If you only want to process one or two files you will have to copy them to hard
disk. It will be usual to input files directly from CD-ROM as they can be very
big. The internal files are much smaller as only a small part of the data is
required.
THE FIRST STF1A FILE (number zero) MUST ALWAYS BE PRESENT as it contains the
level codes necessary to avoid multiple records being extracted.
A parameter file must be given. These are described in the next section.
You can use the supplied parameter file by giving the name as *STF1A, as
described in the following section.
You can also set up your own parameter file, probably by modifying the example
provided.
Attributes (table variables) that are not on the parameter file will not be
processed, so a subset can be extracted by including just the appropriate
entries in the file.
You give a list of numbers for the counties you want to process e.g.
001, 005,...
If all the values for an attribute are zero nothing is written to the output
file for that attribute.
A log file is output to OZGIS.OUT which lists the attributes output and the
position on the file. The positions are of value when generating new
attributes as arithmetic expressions and for selecting attributes
for display.
A parameter file must be used to define the description, units and number of
decimal places for each variable (field).
A sample parameter file is provided: \OZGIS\STF1A.PRM (i.e. called *STF1A)
This file was generated by editing the STF1A data dictionary, and there is no
guarantee that it is correct. (We would be pleased to accept a better version).
The format is fixed, so ensure any file has data in the correct columns if you
modify the file. The first line of the file is a comment, then there is one
line for each Census table variable that is to be processed in the following
format:
8 characters table name
2 characters filler
30 characters variable description
2 characters filler
10 characters units description
2 characters filler
1 digit number of decimal places (0 or 2)
The example parameter file is as follows:
Sample STF1A parameter file
P0010001 TOTAL PERSONS PERSONS 0
P0020001 TOTAL FAMILIES FAMILIES 0
P0030001 TOTAL HOUSEHOLDS HOUSEHOLDS 0
P0040001 PERSONS INSIDE URBANIZED AREA PERSONS 0
P0040002 PERSONS OUTSIDE URBANIZED AREA PERSONS 0
.
.
.
.
.
You should have looked at the early chapters on entering data and displaying
Census-type maps before you look at this example.
Suppose you want to produce a map of 1990 Census data for three counties in
Texas for tract/BNA zones.
First you look up the county FIPS codes in the documentation:
48 Texas
.
.
48 047 Brooks County
.
.
48 117 Deaf Smith County
.
.
48 301 Loving County
So the codes are 047, 117 and 301.
Now set up a directory to work in on the SAME disk as the \OZGIS directory.
e.g.
CD \
MKDIR TEXAS
CD TEXAS
Now get the CD-ROM with the STF1A file for Texas and the TIGER CD-ROMs for
the three counties.
What you need to do is to prepare an attribute file with Census data for
the three counties and three geographic files, one for each county.
You will probably find it most profitable to work through this example
using your own CD-ROM files.
Step1: input the Census data
Mount the STF1A CD-ROM in the drive. Suppose the files are called
TEXAS1A0.DBF ......... TEXAS1A9.DBF.
Select IMPORT DATA FILES from the top menu.
A menu appears:
TUTORIALS & SYSTEM INFORMATION
IMPORT GEOGRAPHIC FILES
IMPORT ATTRIBUTE FILES
IMPORT A NAMES FILE
IMPORT A COMBINE FILE
IMPORT A DEVICE FILE
IMPORT A MARKER FILE
select the option to IMPORT ATTRIBUTE FILES
A new menu appears:
IMPORT A STANDARD FORMAT ATTRIBUTE FILE
IMPORT A SPREADSHEET WK1 FORMAT FILE
IMPORT A DATABASE (SIMPLE) FORMAT ATTRIBUTE FILE
IMPORT A LAMM FORMAT ATTRIBUTE FILE
IMPORT USA CENSUS STF 1A FILES FOR TRACT/BNA
IMPORT USA CENSUS STF 1A FILES FOR BLOCK GROUPS
IMPORT ATLAS DATA FILES
Obviously you now select:
IMPORT USA CENSUS STF 1A FILES FOR TRACT/BNA
Give the input data file as E:/xxx/TEXAS1A0.DBF (using the correct drive)
Give the output attribute file as TEXAS1 (no extension!!)
Give the parameter file as *STF1A
Give the numbers for the counties i.e. 047, 117 and 301.
All the files will be processed. Trace messages will say what is going on.
Exit from the program.
Either print the file OZGIS.OUT or copy it to a file. This is a list of
the census variables and their positions in the attribute file.
Some comments ....... the file name given (TEXAS1A0.DBF) is used as a template
to generate the other file names (TEXAS1A1.DBF etc) and all files in the set
on the CD-ROM are processed.
If the file name is not of the standard form you have to copy the files to
hard disk and rename them.
You can process just some of the files by copying them to hard disk (the first
file, number zero, must always be there). i.e. all the files present are
processed.
Step2: derive census variables (optional)
You now have an attribute file called TEXAS1 ready for mapping. However,
raw Census variables are often not exactly what you want.
Suppose you actually want to map teenagers in the age group 12 to 15 years old.
Also, if you are interested in the way the data are spatially distributed you
have to normalise the data to allow for differences in the total number of
people in the different tract/BNAs.
This can be done as follows:
First look at the file OZGIS.OUT from the data entry process to find the
variable numbers. Suppose it looks like:
1 TOTAL PERSONS
.
.
.
108 12 AND 13 YEARS
109 14 YEARS
110 15 YEARS
.
.
.
The new variable is the sum of the three age variables, divided by the total.
Now select PREPARE DATA FOR DISPLAY from the top menu.
The menu looks like:
PROCESS ATTRIBUTE FILES
PROCESS GEOGRAPHIC FILES
PROCESS NAMES FILES
OUTPUT EXTERNAL DATA FILES
Select PROCESS ATTRIBUTE FILES, which gives another menu:
FORM ATTRIBUTES WITH ARITHMETIC EXPRESSIONS
AMALGAMATE ATTRIBUTE DATA FOR AN COMBINE FILE
Select FORM ATTRIBUTES WITH ARITHMETIC EXPRESSIONS
Now you have to specify an input attribute file, which is here TEXAS1, and a
new output file, say TEXAS2
You can then define a series of arithmetic operations (type H for help)
So you give the arithmetic expression as:
(#108+#109+#110) / #1 * 100.0
You also have to give a description, say "12 TO 15 YEAR OLDS" and a
units description, say "%POP".
Type an expression "E" to exit.
Step 3: Enter the TIGER data
You will have a CD-ROM for each County. Put the first in the drive.
Suppose the files for Brooks County have names tgr48047.d41, tgr48047.f42 etc
Select IMPORT DATA FILES from the top menu.
select IMPORT GEOGRAPHIC FILES and then IMPORT A TIGER FORMAT GEOGRAPHIC FILE.
The TIGER menu is:
TRACTS / BNA
BLOCK GROUPS
BLOCKS
ZIP CODES (IF PRESENT)
VOTING DISTRICTS
SELECT LANDMARKS BY FEATURE CODES
SELECT LINES BY FEATURE CODES
SELECT POINTS BY FEATURE CODES
Obviously, you need to select TRACTS / BNA as that is what you extracted
Census data for.
As before, give the input data as the name of one of the CD-ROM files, say
D:/48/047/TGR48047.F42, and the new geographic file as say BROOKS1
If there are problems reading the files you may have to copy the ones required
to hard disk and rename them, as described in previous sections.
The file BROOKS1 contains the lines that form the boundaries of the tract/BNAs.
Suppose you also would like to display a lines overlay on your map of important
roads.
Looking at the section on feature codes you find that a range of 110 to 128
covers primary and secondary roads.
So, select SELECT LINES BY FEATURE CODES
Give the input data file as before, and the output geographic file as
say BROOKRD
Give the feature code range as found: 110 to 128
Repeat the process for the TIGER files for each of the counties so you
end up with a geographic file of boundaries for tract/BNAs for each county,
and line overlay files for the roads.
Step4: Simplify lines
Often you will want to thin the lines data i.e. throw away a lot of the points.
You do this for several reasons:
. The less the number of vertices the faster map display is.
. You often dont care if the map is particularly accurate, its the attribute
data you are interested in.
. Your screen is low resolution, there is no advantage in having many vertices
for each pixel on the monitor.
. When you form polygons from the lines the number of vertices in some
polygons may exceed system limits.
. Geographic files take less disk space after thinning.
Simplification is an option in the data preparation process which reads a
geographic file and outputs a new one where the line segments have less points.
So, select PREPARE DATA FOR DISPLAY from the top menu.
Select PROCESS GEOGRAPHIC FILES and then select SIMPLIFY (THIN) LINE SEGMENTS
Give the input file as BROOKS1 and the new output file as BROOKS2.
The resolution for thinning is given as the number of pixels. For example,
if you are displaying maps on a standard VGA at 640 X 480 you might give
the resolution as 450 pixels. If you are more interested in speed of
display than appearance give a value of 100.
Repeat for the other files.
Step5: Form polygons from lines
The geographic files of tract/BNAs contain the line segments that form the
boundaries of the Census regions.
You have to form the zone / polygon / line structure by joining the ends of
the lines to form polygons, finding which polygons form the zones and
working out which polygons are inside others.
Select BUILD ZONES FROM LINE SEGMENTS INTO NEW GEOGRAPHIC FILE
Give the input geographic file as BROOKS2
Give the output geographic file as BROOKS
The program will now build the polygons etc.
Repeat for the other tract/BNA boundary files (not the roads!)
If you type "DIR BROO*.GEO" you will find that you have the three geographic
files created during processing:
BROOKS.GEO
BROOKS1.GEO
BROOKS2.GEO
You only need the final one, so you can delete BROOKS1.GEO and
BROOKS2.GEO
Step6: Display simple maps
You can start by displaying some simple maps with SIMPLE CENSUS-TYPE MAPPING.
The first menu appears:
1 TUTORIALS & SYSTEM INFORMATION
2 DISPLAY A NEW MAP
choose the option to "DISPLAY A NEW MAP".
give your attribute file name i.e. TEXAS1
and give your final geographic file name i.e. BROOKS
The data are now processed, the map is displayed, and the next menu appears.
You now have a default map with legend and distribution diagram. The legend
has the numbers of zones in each class on the left and the class value ranges
to the right of the coloured boxes.
If you use an option such as changing the displayed attribute you may have
Refer to the chapter at the front of the manual on using Census mapping if you
have not already looked at the example there.
Step7: Display complex maps
Lets display a map with the three counties tract/BNA geographic files, called
say BROOKS, DEAF and LOVING. The raw attribute file TEXAS1 will be used and
the three road overlay files BROOKSRD, DEAFRD and LOVINGRD will be used.
Type OZGIS to execute the main mapping program.
the first menu enables you to select the type of map or diagram that is
required:
DISPLAY ZONES FOR AN ATTRIBUTE FILE
DISPLAY LINES FOR AN ATTRIBUTE FILE
DISPLAY SITES FOR AN ATTRIBUTE FILE
DISPLAY BIVARIATE ZONES FOR TWO ATTRIBUTE FILES
DISPLAY ZONES & LINES FOR TWO ATTRIBUTE FILES
DISPLAY ZONES AND SITES FOR TWO ATTRIBUTE FILES
DISPLAY GEOGRAPHIC FILES (NO ATTRIBUTES)
DISPLAY ATTRIBUTE FILES (DIAGRAMS)
DISPLAY A SAVED-DISPLAY FILE
DISPLAY A PRESENTATION FILE
Select DISPLAY ZONES FOR AN ATTRIBUTE FILE for a straight forward
choropleth map.
Give the attribute file as TEXAS1 and give one of the geographic boundary
files, say BROOKS.
A map will be displayed that will be the same as that with the Census mapping
process. The difference is that you now have many more options for mapping.
The main mapping menu will now appear on the toolbar:
Attributes
Class
Features
Overlays
Regions
Analyse
Save
First we will add the other two tract/BNA files to the map. This requires
an understanding of map regions which are defined by both a geographic
window and the part of the screen it is to appear on.
select MAP REGIONS.
A menu then appears of the following form:
CHANGE THE DISPLAYED ITEMS IN THE MAP
CHANGE MAP REGION WINDOW (GEOGRAPHIC AREA)
ZOOM MAP REGION WINDOW ABOUT X-HAIR POINT
CHANGE MAP REGION VIEWPORT (SCREEN AREA)
DEFINE NEW REGION FOR QUANTISED ZONES
DISPLAY MORE QUANTISED ZONES ON A REGION
DELETE QUANTISED ZONES FROM REGION
What you do next depends on whether the counties are adjacent or not.
If counties are adjacent, add the files to the existing map region as
follows:
select ZOOM MAP REGION WINDOW ABOUT X-HAIR POINT, choose a location with
the cursor and mouse or arrows (select with left button or Enter). Give
a zoom factor, say 4.
You now have space for the other counties. Select DISPLAY MORE QUANTISED ZONES
ON A REGION and give the next boundary geographic file DEAF. Repeat for LOVING.
If the counties are not adjacent you probably want to display the files in
different parts of the screen in their own regions. Use the option
DEFINE NEW REGION FOR QUANTISED ZONES to do this.
You probably end up with a mess. Use CHANGE MAP REGION WINDOW (GEOGRAPHIC AREA)
and CHANGE MAP REGION VIEWPORT (SCREEN AREA) to clean up the map layout.
You often find that Census maps have very small polygons in the centres of
cities. You can add "blow-ups" of the CBDs by using DEFINE NEW REGION FOR
QUANTISED ZONES to add a geographic file a second time to the map and then
use CHANGE MAP REGION WINDOW (GEOGRAPHIC AREA) to display just the desired
area. (you can also use data preparation options to subset for complete polygons
Finally add the roads. Type ESC to go back to the main map menu and
select DEFINE GEOGRAPHIC OVERLAYS
A menu appears that offers options for several types of overlays:
OVERLAY LINE SEGMENTS FROM A GEOGRAPHIC FILE
OVERLAY MARKERS FOR SITES IN GEOGRAPHIC FILE
OVERLAY NAMES FOR SITES IN GEOGRAPHIC FILE
UNDERLAY POLYGONS FROM GEOGRAPHIC FILE
OVERLAY LINE SEGMENTS FOR FEATURE CODES
OVERLAY MARKERS FOR SITES FOR FEATURE CODES
OVERLAY NAMES FOR SITES FOR FEATURE CODES
UNDERLAY POLYGONS FOR FEATURE CODES
Use OVERLAY LINE SEGMENTS FROM A GEOGRAPHIC FILE to overlay the road geographic
files BROOKSRD, DEAFRD and LOVINGRD one at a time. If you have more than one
region you will have to give the region number - the number is defined by the
order the regions were defined. You could also use OVERLAY LINE SEGMENTS FOR
FEATURE CODES and give a feature code range to subset the lines further.
You can add the names of the tract/BNAs to the map by using OVERLAY NAMES FOR
SITES IN GEOGRAPHIC FILE and adding each of the boundary files.
Having spent all this time you dont want to lose the map, so save it with the
option SAVE DISPLAY FEATURES from the main map menu.
The other options are all described fully elsewhere in the manual.
Federal Information Processing Standards (FIPS) codes are assigned
for a variety of geographic entities, including American Indian and
Alaska Native area, congressional district, county, county subdivision,
metropolitan area, place, and State. The structure, format, and meaning
of FIPS codes used in the census are shown in the 1990 census
Geographic Identification Code Scheme; in the data dictionary portion of
the technical documentation for summary tape files, CD-ROM's, and
microfiche.
The names assigned to Census polygons in OzGIS are generated from the
standard codes.
Tract / BNA name = 3digit county + 5 digit tract FIPS code
Block group name = 3digit county + 5 digit tract FIPS code + first block digit
If you want to input your own data try generating a template attribute data
file with the data preparation options.
These names are unique only within a state.
Summary Tape File 1 (STF 1) contains 100-percent data. Population items
include age, race, sex, marital status, Hispanic origin, household type,
and household relationship. Population items are cross tabulated by age,
race, Hispanic origin, or sex. Housing items include occupancy/vacancy
status, tenure, units in structure, contract rent, meals included in
rent, value, and number of rooms in housing unit. Housing data are cross
tabulated by race or Hispanic origin of householder or by tenure.
Selected aggregates and medians also are provided. Data are presented in
37 population tables (matrices) and 63 housing tables (matrices).
Census blocks are small areas bounded on all sides by visible features such
as streets, roads, streams, and railroad tracks, and by invisible
boundaries such as city, town, township, and county limits, property lines,
and short, imaginary extensions of streets and roads.
Tabulation blocks, used in census data products, are in most cases the
same as collection blocks, used in the census enumeration. In some
cases, collection blocks have been "split" into two or more parts
required for data tabulations. Tabulation blocks do not cross the
boundaries of counties, county subdivisions, places, census tracts or
block numbering areas, American Indian and Alaska Native areas,
congressional districts, voting districts, urban or rural areas, or
urbanized areas. The 1990 census is the first for which the entire
United States and its possessions are block-numbered.
Blocks are numbered uniquely within each census tract or BNA. A block
is identified by a three-digit number, sometimes with a single
alphabetical suffix. Block numbers with suffixes generally represent
collection blocks that were "split" in order to identify separate
geographic entities that divide the original block. For example, when a
city limit runs through data collection block 101, the data for the
portion inside the city is tabulated in block 101A and the portion
outside, in block 101B. A block number with the suffix "Z"
represents a "crews-of-vessels" entity for which the Census
Bureau tabulates data, but that does not represent a true geographic
area; such a block is shown on census maps associated with an anchor
symbol and a census tract or block numbering area with a .99 suffix.
A geographic block group (BG) is a cluster of blocks having the same
first digit of their three-digit identifying numbers within a census
tract or block numbering area (BNA). For example, BG 3 within a census
tract or BNA includes all blocks numbered between 301 and 397. In most
cases, the numbering involves substantially fewer than 97 blocks.
Geographic BG's never cross census tract or BNA boundaries, but may
cross the boundaries of county subdivisions, places, American Indian
and Alaska Native areas, urbanized areas, voting districts, and
congressional districts. BG's generally contain between 250 and 550
housing units, with the ideal size being 400 housing units.
Block numbering areas (BNA's) are small statistical subdivisions of
a county for grouping and numbering blocks in nonmetropolitan counties
where local census statistical areas committees have not established
census tracts. State agencies and the Census Bureau delineated BNA's
for the 1990 census, using guidelines similar to those for the
delineation of census tracts. BNA's do not cross county boundaries.
BNA's are identified by a four-digit basic number and may have a
two-digit suffix; for example, 9901.07. The decimal point separating
the four-digit basic BNA number from the two-digit suffix is shown in
printed reports, in microfiche, and on census maps; in machine-readable
files, the decimal point is implied. Many BNA's do not have a suffix;
in such cases, the suffix field is left blank in all data products. BNA
numbers range from 9501 through 9989.99, and are unique within a county
(numbers in the range of 0001 through 9499.99 denote a census tract).
The suffix .99 identifies a BNA that was populated entirely by persons
aboard one or more civilian or military ships. A "crews-of-vessels" BNA
appears on census maps only as an anchor symbol with its BNA number (and
block numbers on maps showing block numbers); the BNA relates to the ships
associated with the onshore BNA's having the same four-digit basic number.
Suffixes in the range .80 through .98 usually identify BNA's that either
were revised or were created during the 1990 census data collection
activities. Some of these revisions produced BNA's that have extremely
small land area and ay have little or no population or housing. For data
analysis, such a BNA can be summarized with an adjacent BNA.
Census tracts are small, relatively permanent statistical subdivisions of a
county. Census tracts are delineated for all metropolitan areas (MA's) and
other densely populated counties by local census statistical areas
committees following Census Bureau guidelines (more than 3,000 census
tracts have been established in 221 counties outside MA's). Six States
(California, Connecticut, Delaware, Hawaii, New Jersey, and Rhode Island)
and the District of Columbia are covered entirely by census tracts. Census
tracts usually have between 2,500 and 8,000 persons and, when first
delineated, are designed to be homogeneous with respect to population
characteristics, economic status, and living conditions. Census tracts do
not cross county boundaries. The spatial size of census tracts varies
widely depending on the density of settlement. Census tract boundaries are
delineated with the intention of being maintained over a long time so that
statistical comparisons can be made from census to census. However,
physical changes in street patterns caused by highway construction, new
development, etc., may require occasional revisions; census tracts
occasionally are split due to large population growth, or combined as a
result of substantial population decline. Census tracts are referred to
as "tracts" in all 1990 data products.
Census tracts are identified by a four-digit basic number and may have
a two-digit suffix; for example, 6059.02. The decimal point separating
the four-digit basic tract number from the two-digit suffix is shown in
printed reports, in microfiche, and on census maps; in machine-readable
files, the decimal point is implied. Many census tracts do not have a
suffix; in such cases, the suffix field is left blank in all data
products. Leading zeros in a census tract number (for example, 002502)
are shown only on machine-readable files.
Census tract numbers range from 0001 through 9499.99 and are unique
within a county (numbers in the range of 9501 through 9989.99 denote a
block numbering area). The suffix .99 identifies a census tract that
was populated entirely by persons aboard one or more civilian or
military ships. A "crews-of-vessels" census tract appears on
census maps only as an anchor symbol with its census tract number (and
block numbers on maps showing block numbers). These census tracts
relate to the ships associated with the on-shore census tract having
the same four-digit basic number. Suffixes in the range .80 through .98
usually identify census tracts that either were revised or were created
during the 1990 census data collection activities. Some of these
revisions may have resulted in census tracts that have extremely small
land area and may have little or no population or housing. For data
analysis, such a census tract can be summarized with an adjacent census
tract.
The primary political divisions of most States are termed "counties." In
Louisiana, these divisions are known as "parishes." In Alaska, which has no
counties, the county equivalents are the organized "boroughs" and the
"census areas" that are delineated for statistical purposes by the State of
Alaska and the Census Bureau. In four States (Maryland, Missouri, Nevada,
and Virginia), there are one or more cities that are independent of any
county organization and thus constitute primary divisions of their States.
These cities are known as "independent cities" and are treated as
equivalent to counties for statistical purposes. That part of Yellowstone
National Park in Montana is treated as a county equivalent. The District of
Columbia has no primary divisions, and the entire area is considered
equivalent to a county for statistical purposes.
Each county and county equivalent is assigned a three-digit FIPS code
that is unique within State. These codes are assigned in alphabetical
order of county or county equivalent within State, except for the
independent cities, which follow the listing of counties.
A hierarchical geographic presentation shows the geographic entities
in a superior/subordinate structure in census products. This structure
is derived from the legal, administrative, or areal relationships of
the entities. The hierarchical structure is depicted in report tables
by means of indentation, and is explained for machine-readable media in
the discussion of file structure in the geographic coverage portion of
the abstract in the technical documentation. An example of hierarchical
presentation is the "standard census geographic hierarchy": block, within
block group, within census tract or block numbering area, within place,
within county subdivision, within county, within State, within division,
within region, within the United States. Graphically, this is shown as:
ZIP Codes are administrative units established by the United States
Postal Service (USPS) for the distribution of mail. ZIP Codes serve
addresses for the most efficient delivery of mail, and therefore
generally do not respect political or census statistical area
boundaries. ZIP Codes usually do not have clearly identifiable
boundaries, often serve a continually changing area, are changed
periodically to meet postal requirements, and do not cover all the land
area of the United States. ZIP Codes are identified by five-digit codes
assigned by the USPS. The first three digits identify a major city or
sectional distribution center, and the last two digits generally
signify a specific post office's delivery area or point. For the 1990
census, ZIP Code data are tabulated for the five-digit codes in
STF 3B.
The file is segmented into 10 dBase III (.DBF) files, designated
STF1A0ss.DBF through STF1A9ss.DBF where ss is the two-character State
abbreviation. The STF1A0 segment contains the full 67 field identification
section. The identification field names are shown in the Data Dictionary
chapter of the technical documentation. Segments STF1A1 through STF1A9
each contain seven identification fields repeated from the STF1A0 segment.
They are shown below.
Identification Fields Common To All Segments
SUMLEV Summary Level
STATEFP State (FIPS)
CNTY County (FIPS)
COUSUBFP County Subdivision (FIPS)
PLACEFP Place (FIPS)
TRACTBNA Census Tract/Block Numbering Area
BLCKGR Block Group
LOGRECNU Logical Record Number
The segments are divided as shown below. Tables 12 and 13 go across
segments.
Data Tables In Each Segment
STF1A0 P1 - P10
STF1A1 P11 - P12(pt.2)
STF1A2 P12(pt. 3) - P12(pt. 5)
STF1A3 P12(pt. 6) - P12(pt. 8)
STF1A4 P12(pt. 9) - P13(pt. 1)
STF1A5 P13(pt. 2) - P19
STF1A6 P20 - P35
STF1A7 P36, H1 - H20
STF1A8 H21 - H40
STF1A9 H41 - H55
Parts of Table P12
(Each part contains 31 categories of age)
Part 1 White males
Part 2 White females
Part 3 Black males
Part 4 Black females
Part 5 American Indian, Eskimo or Aleut males
Part 6 American Indian, Eskimo or Aleut females
Part 7 Asian or Pacific Islander males
Part 8 Asian or Pacific Islander females
Part 9 Other race males
Part 10 Other race females
Parts of Table P13
(Each part contains 31 categories of age)
Part 1 Hispanic origin males
Part 2 Hispanic origin females
You can process all or some of the files.
Fields in numeric data tables are named according to a convention which
identifies the tables and the sequence of the data item within the table.
The 310 data items in P12, for example, are identified as P0120001 through
P0120310. The one data item in table H23A is identified as H023A001.
Components Of The Field Name
Character 1 P or H
Character 2-4 Table number; right justified with
leading zeroes
Character 5 Sub-table letter; zero if not applicable
Character 6-8 Item number; right justified with
leading zeroes
The 1990 Census TIGER/Line file provides digital data for all 1990 census
map features and boundaries, the associated 1990 census final tabulation
geographic area codes (such as 1990 census block numbers), and the codes
for the January 1, 1990 legal and statistical areas on both sides of each
line segment of every mapped feature. This version also contains the final
voting district codes and the 1990 census designated place codes.
The 1990 Census TIGER/Line files cover the entire United States, Puerto
Rico, the Virgin Islands of the United States, American Samoa, Guam, the
Northern Mariana Islands, Palau, the other Pacific entities that were part
of the Trust Territory of the United States for the 1980 census (the
Marshall Islands and the Federated States of Micronesia), and the Midway
Islands (to provide complete mapping within the boundaries of the State of
Hawaii).
The normal geographic coverage for a 1990 Census TIGER/Line file is a
county. The files can be combined to cover the whole Nation and its
possessions. Each 1990 Census TIGER/Line file consists of 12 record types
that collectively contain geographic information (attributes) such as
address ranges and ZIP codes for street segments (only in areas covered by
the 1980 GBF/DIME-Files), names and codes of feature types, codes for legal
and statistical entities, selected 1980 census geographic area codes,
latitude/longitude coordinates of linear and point features, landmark
features, area landmarks, and area and polygon boundaries. The 12 record
types are on the tape as 12 separate files.
The 1990 Census TIGER/Line file contains basic information for 1990 census
geographic area codes, basic map features and their names, and address
ranges in the form of 12 "Record Types." The record types are as follows:
1. Basic Data Records (Individual Feature Segment Records)
2. Shape Coordinate Points (Feature Shape Records)
3. Additional Decennial Census Geographic Area Codes
4. Index to Alternate Feature Names
5. Feature Name List
6. Additional Address Range and ZIP Code(2) Information
7. Landmark Features
8. Area Landmarks
A. Additional Polygon Geographic Area Codes
I. Area Boundaries
P. Polygon Location
R. Record Number Range
Each segment record contains appropriate decennial census and, when
appropriate, FIPS(1) geographic area codes, latitude/longitude coordinates
for all line segments and point features, the name of the feature
(including the relevant census feature class code identifying the segment
by category), and, for areas formerly covered by the GBF/DIME-Files, the
address ranges and the ZIP Code associated with those address ranges for
each side of street segments. For other areas, the TIGER/Line files do not
contain address ranges or ZIP Codes. The shape records provide coordinate
values that describe the shape of those feature segments that are not
straight.
Record types 1,2,3 and 7 are processed by OzGIS. The types used depend on
the options chosen:
Record Type 1: Basic Data Record
Record Type 1 provides a single record for each unique line segment in the
1990 Census TIGER/Line file. The end points of the line segments are
expressed in latitude/longitude coordinate values in degrees and decimal
fractions of a degree to six decimal places. This record also contains
address ranges and ZIP codes (in selected areas) and geographic area codes
for each side of the line segment. By convention, if one is standing at
the "from" coordinate position facing the "to" coordinate position,
data listed in the fields carrying a right qualifier would indeed be found
to the right of the line segment. Data users can collect the necessary
segments to construct polygons and features that intersect from the
information contained in this basic record.
Record Type 2: Shape Coordinate Points
Record Type 2 provides an additional series of latitude and longitude
coordinate values that describe the shape of each line segment that is not
straight for the associated Record Type 1. All coordinate values are
expressed in degrees and decimal fractions of a degree of latitude and
longitude. The decimals are carried to six places to permit the
representation of lines that are very close to one another. If the segment
in Record Type 1 is a straight line, there will not be a Record Type 2.
Record Type 3: Additional Decennial Census Geographic Area Codes
Record Type 3 includes the 1990 voting district codes provided to the
Census Bureau for the 1990 Census Redistricting Data Program. Record Type
3 also includes some 1980 census geographic area codes and 1990 census
geographic area codes not included on Record Type 1. The 1980 census block
numbers are available only for areas covered by the 1980 GBF/DIME-Files.
During the conversion of the 1980 GBF/DIME-Files to the TIGER data base
format, some 1980 census block numbers may have been deleted or changed.
Users are advised to check all 1980 census geographic area codes,
especially any 1980 block numbers, before using them in a planned
application. The Census Bureau has not verified any of the 1980 census
geographic area codes in these files. There will be discrepancies between
the geographic area boundaries and codes in these files and the 1980 census
maps, which are the basis for the 1980 census tabulations.
The TIGER/Line files may contain 1980 block numbers for portions of the
country where the Census Bureau did not tabulate 1980 census data by block
or block group. These situations occur because these portions of the TIGER
file originated from the 1980 GBF/DIME-Files that extended beyond the 1980
block-numbered area. Data users concerned about the validity of 1980 block
numbers are advised to discard all 1980 block numbers that do not
correspond to block numbers in the 1980 MARF or 1980 STF files.
Record Type 6: Additional Address Range and ZIP Code Data
Record Type 6 provides additional address range information for a street
segment when the information cannot be presented as a single address range
(e.g., the house/building numbers are not uniformly arranged to form an
address range). Additional ZIP Codes, if any, also appear in Record Type 6
for corresponding address ranges. Record Type 6 appears only for those
counties that have address ranges and ZIP Code information in the TIGER
data base. There is no assurance that the address ranges provided on
Record Type 6 will be "shorter" than those appearing on Record Type 1.
Data users must use Record Type 6 to obtain the complete picture of the
potential address ranges along a segment.
Record Type 7: Landmark Features
Record Type 7 contains the area and point landmarks in the Census Bureau's
TIGER data base. During the extraction of this data, we assigned a
temporary Landmark Identification Number that we use to link the landmark
attributes to the polygons that comprise the landmark. If there is no
landmark in a county file, there will be no Record Type 7 or Record Type 8
for that county file.
United States - The 50 States and the District of Columbia.
States and Statistically Equivalent Areas - The 50 States; in addition, we
treat the District of Columbia, Puerto Rico, and each of the outlying
areas-American Samoa, Guam, the Northern Mariana Islands, Palau, and the
Virgin Islands of the United States-as statistical equivalents to States
for presentation. We also have TIGER/Line files for the Marshall Islands,
the Federated States of Micronesia, and the Midway Islands.
Counties, Parishes, Statistically Equivalent Areas - The first-order
divisions of each State, the District of Columbia, Puerto Rico, and the
outlying areas: counties for 48 States; parishes for Louisiana; boroughs
and census areas for Alaska; independent cities in Maryland, Missouri,
Nevada, and Virginia; Yellowstone National Park in Montana, "District of
Columbia" for the District of Columbia, municipios in Puerto Rico; other
entities in the outlying areas.
Minor Civil Divisions (MCDs) - Legally defined subcounty areas such as
towns and townships. For the 1990 census, these are found in 28 States,
Puerto Rico, and the outlying areas.
Sub-MCDs - Legally defined subdivisions of a minor civil division;
specifically, subbarrios in Puerto Rico, and municipal districts in the
Federated States of Micronesia.
Incorporated Places - Legal units incorporated as a city, town (excluding
the New England States, New York, and Wisconsin), borough (excluding Alaska
and New York), or village.
American Indian Reservations - American Indian areas with boundaries
established by treaty, statute, and/or executive or court order.
Alaska Native Regional Corporations (ANRCs) - Corporate entities
established by the Alaska Native Claims Settlement Act (P.L. 92-203) to
carry out the business and non-profit operations established by and for
Native Alaskans under the Act. Twelve ANRCs have specific boundaries and
cover the State of Alaska except for the Annette Islands Reserve.
Statistical Areas
Alaska Native Village Statistical Areas (ANVSAs) - 1990 census statistical
areas that delineate the settled area of each Alaska Native village (ANV).
Officials of Alaska Native Regional Corporations (ANRCs) and other
appropriate State officials delineated the ANVSAs for the Census Bureau for
the sole purpose of presenting census data.
Tribal Designated Statistical Areas (TDSAs) - Geographic areas delineated
for 1990 census data tabulation purposes by tribal officials of Federally
and State-recognized tribes outside of Oklahoma that do not have a legally
defined reservation.
Tribal Jurisdiction Statistical Areas (TJSAs) - Geographic areas delineated
for 1990 census data tabulation purposes by tribal officials in Oklahoma
for Federally recognized tribes that do not have a legally defined
reservation.
Census County Divisions (CCDs) - Areas delineated by the Census Bureau in
cooperation with State and local officials in States where MCDs are not
adequate for reporting subcounty statistics.
Unorganized Territories (UTs) - Areas delineated by the Census Bureau for
those portions of a State with MCDs where MCDs do not exist or are not
adequate for reporting subcounty statistics.
Census Designated Places (CDPs) - Densely settled population centers
without legally defined corporate limits or corporate powers, defined in
cooperation with State officials and local data users.
Census Tracts - Small, locally delineated statistical areas within selected
counties, generally having stable boundaries and, when first established by
local committees, designed to have relatively homogeneous demographic
characteristics.
Block Numbering Areas (BNAs) - Areas delineated by State governments or the
Census Bureau for the purpose of grouping and numbering blocks in counties
without census tracts.
Census Blocks - Small, usually compact areas, usually bounded by streets
and other prominent physical features as well as boundaries of legal areas
for which the Census Bureau tabulates data. Blocks do not cross county,
census tract, or BNA boundaries.
Voting Districts (VTDs) - For the 1990 census, the term "voting district"
replaces the 1980 census term "election precinct." A voting district is
any of a variety of areas (for example, election districts, precincts,
legislative districts, wards) defined by State and local governments for
purposes of elections. The 1990 voting district codes that appear in the
1990 census version of the TIGER/Line files were supplied by the State
under the 1990 Census Redistricting Data Program. The boundaries of the
voting districts recorded in the TIGER/Line files may represent pseudo-
voting districts; the States were required to have voting districts follow
1990 census block boundaries, and therefore they may have had to relocate
the boundaries of actual voting districts to a nearby feature used as a
block boundary. States had the option of participating in the program on a
county-by-county basis. Voting districts do not appear in all TIGER/Line
files.
Data can be extracted from the TIGER files and subset for display by
feature codes.
Feature codes are derived from the Census Feature Class Codes (CFCC)
by changing the leading alphabetic character by its position in the
alphabet.
This is a series of codes that provides more detailed information on the
classification of the line segment, such as class of road, class of stream,
and so forth.
A list of these codes follows.
CFCC CLASSIFICATION A = ROAD FEATURES
100 Road, Classification Unknown or Not Elsewhere Classified
101 Road, undivided
102 Road, undivided, in tunnel
103 Road, undivided, underpassing
104 Road, undivided, rail line in center
105 Road, divided
106 Road, divided, in tunnel
107 Road, divided, underpassing
108 Road, divided, rail line in center
110 Primary road, interstate highway and limited access road
111 Primary road, interstate highway and limited access road, undivided
112 Primary road, interstate highway and limited access road,
undivided, in tunnel
113 Primary road, interstate highway and limited access road,
undivided, underpassing
114 Primary road, interstate highway and limited access road,
undivided, rail line in center
115 Primary road, interstate highway and limited access road, divided
116 Primary road, interstate highway and limited access road, divided,
in tunnel
117 Primary road, interstate highway and limited access road, divided,
underpassing
118 Primary road, interstate highway and limited access road, divided,
rail line in center
120 Secondary road, U.S. highway not classified 110, and state roads
121 Secondary road, U.S. highway not classified 110, and state roads,
undivided
122 Secondary road, U.S. highway not classified 110, and state roads,
undivided, in tunnel
123 Secondary road, U.S. highway not classified 110, and state roads,
undivided, underpassing
124 Secondary road, U.S. highway not classified 110, and state roads,
undivided, rail line in center
125 Secondary road, U.S. highway not classified 110, and state roads,
divided
126 Secondary road, U.S. highway not classified 110, and state roads,
divided, in tunnel
127 Secondary road, U.S. highway not classified 110, and state roads,
divided, underpassing
128 Secondary road, U.S. highway not classified 110, and state roads,
divided, rail line in center
130 Connecting road, county roads, and roads not classified as 110 or
120
131 Connecting road, county roads, and roads not classified as 110 or
120, undivided
132 Connecting road, county roads, and roads not classified as 110 or
120, undivided, in tunnel
133 Connecting road, county roads, and roads not classified as 110 or
120, undivided, underpassing
134 Connecting road, county roads, and roads not classified as 110 or
120, undivided, rail line in center
135 Connecting road, county roads, and roads not classified as 110 or
120, divided
136 Connecting road, county roads, and roads not classified as 110 or
120, divided, in tunnel
137 Connecting road, county roads, and roads not classified as 110 or
120, divided, underpassing
138 Connecting road, county roads, and roads not classified as 110 or
120, divided, rail line in center
140 Neighborhood roads, city streets and unimproved roads
141 Neighborhood roads, city streets and unimproved roads, undivided
142 Neighborhood roads, city streets and unimproved roads, undivided,
in tunnel
143 Neighborhood roads, city streets and unimproved roads, undivided,
underpassing
144 Neighborhood roads, city streets and unimproved roads, undivided,
rail line in center
145 Neighborhood roads, city streets and unimproved roads, divided
146 Neighborhood roads, city streets and unimproved roads, divided, in
tunnel
147 Neighborhood roads, city streets and unimproved roads, divided,
underpassing
148 Neighborhood roads, city streets and unimproved roads, divided,
rail line in center
150 Jeep trail, passable only by four-wheel drive (4WD) vehicle
151 Jeep trail, passable only by four-wheel drive (4WD) vehicle,
undivided
152 Jeep trail, passable only by four-wheel drive (4WD) vehicle,
undivided, in tunnel
153 Jeep trail, passable only by four-wheel drive (4WD) vehicle,
undivided, underpassing
160 Special Road Feature
161 Cul-de-sac
162 Traffic circle
163 Cloverleaf or interchange
164 Service drive
165 Ferry crossing
170 Other Thoroughfare
171 Walkway
172 Stairway
173 Alley
NOTE: In the portion of the TIGER/Line file prepared from the GBF/DIME-
Files, the roads are classified as Class 4 roads with a few exceptions.
The interstate highways that were identified by name as such in the
GBF/DIME-File, are classified as Class 1 roads. Also, in the GBF/DIME-File
coverage areas, users may not find many roads with alternate names; if an
alternate name is provided, it usually represents another local name and
not a Route Number.
CFCC CLASSIFICATION B = RAIL FEATURES
200 Railroad, Classification Unknown or Not Elsewhere Classified
201 Railroad track
202 Railroad track, in tunnel
203 Railroad track, underpassing
210 Railroad Main Track
211 Railroad main track
212 Railroad main track, in tunnel
213 Railroad main track, underpassing
220 Railroad Spur Track
221 Railroad spur track
222 Railroad spur track, in tunnel
223 Railroad spur track, underpassing
230 Railroad Yard
231 Railroad yard
232 Railroad yard, in tunnel
233 Railroad yard, underpassing
240 Railroad Ferry Crossing
250 Other Rail Feature
251 Carline
252 Cog railroad, incline railway, or logging tram
CFCC CLASSIFICATION C = PIPELINES, POWER TRANSMISSION LINES, AND
MISCELLANEOUS TRANSPORTATION FEATURES
300 Special Transportation Feature, Classification Unknown or Not
Elsewhere Classified
310 Pipeline
320 Power Transmission Line
330 Other Special Transportation Feature
331 Aerial tramway, monorail, or ski lift
CFCC CLASSIFICATION D = LANDMARK FEATURES
400 Landmark Feature, Classification Unknown or Not Elsewhere
Classified
410 Military installation
420 Multihousehold and transient quarters
421 Apartment building or complex
422 Rooming or boarding house
423 Trailer court or mobile home park
424 Marina
425 Crew of vessel
426 Housing facility for workers
427 Hotel, motel, resort, spa, YMCA, or YWCA
428 Campground
429 Shelter or mission
430 Custodial facility
431 Hospital
432 Halfway house
433 Nursing home, retirement home, or home for the aged
434 County home or poor farm
435 Orphanage
436 Jail or detention center
437 Federal penitentiary, state prison, or prison farm
440 Educational or religious institution
441 Sorority or fraternity
442 Convent or monastery
443 Educational institution
444 Religious institution
450 Transportation terminal
451 Airport or airfield
452 Train station
453 Bus terminal
454 Marine terminal
455 Seaplane anchorage
460 Employment center
461 Shopping center or major retail center
462 Industrial building or industrial park
463 Office building or office park
464 Amusement center
465 Government center
466 Other employment center
470 Tower
471 Lookout tower
480 Open space
481 Golf course
482 Cemetery
483 National park or forest
484 Other federal land
485 State or local park or forest
490 Special purpose landmark
491 Post office box ZIP code
CFCC CLASSIFICATION E = OTHER PHYSICAL FEATURES
500 Physical Feature, Classification Unknown or Not Elsewhere
Classified
510 Fence line
520 Topographic feature
521 Ridge line
522 Mountain peak
CFCC CLASSIFICATION F = NONVISIBLE BOUNDARIES
600 Nonvisible Boundary, Classification unknown or not Elsewhere
Classified
610 Nonvisible Political Boundary
611 Offset corporate boundary
612 Corporate Corridor
613 Nonvisible interpolated boundary, polygon definition line for
hydrological areas
620 Feature Extension, Not Otherwise Classified
621 Automated extension
622 Irregular block extension
623 Closure extension
624 Nonvisible separation line
625 Nonvisible corporate corridor centerline
630 Point-to-Point Line
640 Property Line
650 ZIP Code Boundary
660 Map Edge
670 Statistical Boundary
671 1980 Statistical Boundary
672 1990 Block Boundary
673 1990 Statistical Boundary
674 1990 Statistical Boundary, Tabulation Areas Only
CFCC CLASSIFICATION H = HYDROGRAPHIC FEATURES
800 Water Feature, Classification Unknown or Not Elsewhere Classified
801 Shoreline of perennial water feature
802 Shoreline of intermittent water feature
810 Stream
811 Perennial stream
812 Intermittent stream or wash
813 Braided stream
820 Canal, Ditch, or Aqueduct
821 Perennial canal, ditch, or aqueduct
822 Intermittent canal, ditch, or aqueduct
830 Lake or pond
831 Perennial lake or pond
832 Intermittent lake or pond
840 Reservoir
841 Perennial reservoir
842 Intermittent reservoir
850 Bay, Estuary, Gulf, Sound, Sea, or Ocean
851 Bay, estuary, gulf, or sound
853 Sea or ocean
860 Gravel Pit or Quarry Filled With Water
870 Nonvisible Water Area Definition Boundary
871 USGS closure line
872 Census computed center line
873 Census international water boundary, 10-mile limit, area
measurement line
874 Census water boundary, inland or coastal or Great Lakes
875 3-mile limit water boundary
880 Special Water Feature
881 Glacier
The purpose of this Appendix is to provide definitions for a number of terms used within this Guide. Most of these terms are commonly used words or phrases which have taken on a more precise technical meaning in one of the areas spanned by the OzGIS system. Technical terms have been borrowed from the jargon of statistics, data processing, computer software and hardware, cartography, and graphic arts. Because of the diversity of these disciplines, it is unlikely that a potential OzGIS user will have developed a level of expertise in each. This glossary should provide most of the information necessary for communicating the basic concepts of OzGIS.
Area - 1) A measurement of the size of a geographical region whose shape is displayed on the OzGIS monitor. 2) An arbitrary portion of the face of the monitor.
Attribute - A general term for the variable associated with a set of geographic zones, lines or sites to be processed by OzGIS. Attributes may be variates, statistics or simply data collected for each item. Note that the modes of display for an attribute are usually referred to as "single variate" or "bi-variate". See also Variate and Statistic.
Background - The informationless area displayed on the monitor around a map and its associated components. Usually given a user selected, neutral colour such as black or white.
Bit - A unit of information representing the value (either 1 or 0) of a single binary digit.
Bivariate - A display of the relative distribution of two different sets of statistics on the same map. It must be noted that no relationship between the two statistics is implied by the display. For example, if the distribution of little old ladies is displayed simultaneously with the distribution of cricket players, the result is not a display of the distribution of little old ladies who play cricket. See also Variate.
Boundary - A set of lines displayed on the monitor to represent the edges of polygons defined to the system. Often the same as zone edges.
Byte - A group of eight bits. See also Bit.
Catchment - The region of influence around a site e.g. suburbs around a shopping centre where most of the customers live.
Character - A single symbolic pattern which may be displayed on either the monitor or terminal. It may be alphabetic, numeric, or punctuational, as the normal symbols encountered on a typical typewriter keyboard, or a special symbol generated for display as an entity, such as a square root symbol.
Choropleth Map - A map portraying the values of an attribute averaged over data collection units (or zones) and represented by a symbol covering the entire unit. A map displayed by OzGIS represents the zones by a uniform colour.
Class - A convenient subdivision of the total range of values of a particular statistical variate. Classes are usually chosen to make computations or analyses less labourious, or to make the results of such analyses more obvious or meaningful. For example, the range of a set of values might be divided into ten equal classes in order to highlight items in the top ten percent. See also Variate, Class Boundary, Class Interval and Class Number.
Class Boundary - The special values of variates which determine the upper and lower limits of the range of a class. See also Class.
Class Interval - The range of variate values between the upper and lower limits of the class. See also Class.
Class Number - A cardinal number assigned to each class into which a particular statistical range has been divided. Conventionally, the class whose members have the lowest magnitude is assigned number 1, with class numbers increasing uniformly as the magnitude of class values increases. See also Class.
Colour - One of the combinations of blue, green, and red which may be specified for display on the monitor. The total number of colours available depends on the display system.
Colour Space - The range of colours which may be specified for display on the colour monitor. Since the colours are specified as values of blue, green, and red, it is convenient to think of the colour space as a cube located on a standard three dimensional coordinate system. Black is placed at the origin, with each of the x, y and z axes representing blue, green, and red, respectively. The range of possible values is 0.0 to 1.0 on each axis of the cube.
Continuous Colour - A method of representating statistical values associated with map zones by graduating zone colours to correspond with changes in statistical value. From a user defined, or default, sequence of colours, OzGIS generates the intermediate colours to provide a 12 colour graduated path through the colour space. The statistic to be represented is quantized into 12 equal value classes, and the classes are assigned colours from the generated colour sequence. This allows small changes in statistical value to be represented by subtle changes in colour, while large changes in value may be visually observed as significant colour differences.
Controller - A general term applied to a piece of intermediate equipment in the data path between the electrical signals of a processor and their physical realization in a peripheral device. Within OzGIS, the term will most often be used for the Color Display Controller. It will be used to a lesser extent to describe interface controllers for the various disc and tape drives.
Coordinate - One of a pair of numbers which designates the location of a geographic point with respect to another known point. Geographic files for entry into the system under OzGIS must have their points specified in appropriately scaled and formatted coordinates. The coordinates specified by the user are converted by OzGIS for display on the monitor. On the monitor screen, the origin is in the lower left hand corner of the viewing area. The coordinates of a point on the monitor screen are specified by their distance right and up from the origin
Crosshair Cursor - A pair of lines at right angles to each other which is displayed on the monitor to designate the location of a certain point of interest. Under most circumstances, the location of the crosshair cursor may be controlled by movements of the mouse. See also Box Cursor, and Joystick.
Data - Numerical values associated with certain physical phenomena, such as 128 cm long, 14 years old, or 43 kangaroos. As a generality, OzGIS was not designed to handle data, but rather the statistics derived from data, such as average length, medium age, or number of kangaroos per hectare. See also Statistics.
Decile - One of the nine data values which divide the range of a variate into ten equal sized classes. See also Quantile and Percentile.
Default - A set of parameters automatically selected by OzGIS in the absence of any stated preference by the user. The actual default parameters may be defined by the user in the users default file. For example, OzGIS may initially display a map by arbitrarily selecting zone colours from a palette of possible shades which the user selected previously. After this default colouring, the user may wish to change some particular zone colour to improve the appearance of the display.
Disc - An electronic device for storing digital data on a rotating plate coated with magnetic material. See also Controller.
Display - As a verb, the act of presenting information on the monitor or terminal for the purpose of visually communicating that information to the user. This includes all the procedures necessary to correctly present the information in a format suitable for both the equipment and the viewer. Example: "A map is displayed on the monitor, while a menu is displayed on the terminal". As a noun, the presentation which is visually perceived when a user looks at the screen of the monitor or terminal; the total information content on the screen. Examples: "The terminal display indicates the options possible now"; "This map display is too red". See also Monitor and Terminal.
Display Elements - The components or items of a display on the OzGIS monitor; for example, legend, title, image map, boundaries, image symbols, histograms.
Distribution - The manner in which a number of samples of data are spread across the range of possible values. May be a subjective statement, such as: "These data appear to have an even distribution". More often, some quantifiable measure will be given such as: "These data have a normal distribution with a mean of 40 and standard deviation of 3". Sometimes, distribution information will be presented in graphical form, such as a histogram or scatter diagram.
Equal Value Quantization - A method of dividing the range of values of a statistical variate into a number of classes where the magnitude of the range of each class is the same. See also Class.
Excluded Zone - A zone displayed on the map and coloured with a special shade indicating that it has not been used for quantization or has been omitted from the area of interest.
File - A number of data items grouped together and considered as a unit for convenience of storage and retrieval by a computer. Within OzGIS, such files are stored as distinct entities on disk. Files are identified by media designation, name, and type. The OzGIS user normally supplies only the file name, but the storage media may also be specified. The file type is supplied by the system. The same name may be used for files of different types, but within a particular type, no two files may have the same name.
Frequency - A statistical term referring to the number of members of a population falling into a specified class. See also Class.
Geographic Data - Digitized map data which are referenced to a geographic (or spatial) coordinate system, usually a map projection.
Graphics - Data which can be displayed on the monitor in terms of lines points and text, as opposed to colouring and filling regions of the screen. Used to refer to geographic and symbol data.
Histogram - A type of bar graph in which vertical rectangles are erected on the horizontal axis with the height of each bar representing the frequency, and the width representing the corresponding class interval,
for each of the classes of a particular variate. OzGIS can display
such statistical information on the monitor. See also Scatter Diagram,
and Class.
Information - The subjective knowledge which may be associated with an objective set of data. The ages and locations of children are data; the distribution of school age children is statistic; where the schools should be built is information. See also Data and Statistics.
Interval - The numerical distance between the upper and lower limits of a class.
Joystick - An electro-mechanical device which converts the positions of a small lever into electrical voltages. The voltages are further converted into digital signals which are used by the PDP11 to position various cursor patterns on the monitor screen. See also Box Cursor, and Crosshair Cursor.
Legend - A display on the monitor which indicates the correspondence between the statistical values and their associated colours or symbols as defined for a particular map. The legend usually occupies approximately the rightmost one fifth of the viewing area of the monitor and has two general forms, single variate and bivariate. One type of single variate legend consists of a column of coloured rectangles beside which are numbers indicating the corresponding class boundaries for those colours. The other is a rectangular column with colours gradually changing from top to bottom, and an upper and lower number indicating the range across which the "Continous Colour" varies. The bivariate legend consists of a 45 degree parallelogram divided left to right and up and down into coloured smaller parallelograms. A set of numbers along the left side indicates the class boundaries of the primary variate, while similar numbers across the upper side indicate the secondary variate class boundaries.
Line - This term has three special meanings within OzGIS in addition to its normal English usage. (1) Any set of contiguous segments comprising the section of a zone boundary which has one zone on its right and a second zone on its left as part of a map. (2) Any contiguous set of segments as part of a graphics display. (3) A set of alpha-numeric characters meant to be displayed as one row on either the monitor or the terminal.
Location - The position of a datum point, or pixel, on the monitor screen. This is given by its x and y coordinates, with the origin in the lower left hand corner. The range of values depends on the display system. Lookup Table (LUT) - A table in the display system which can modify the value in memory for display purposes.
Map - Geographic data which can be displayed on the monitor by colouring and filling regions of the screen or as lines or symbols.
Map Projection - Refers to the coordinate system used for processing the display of a map.
Markers - Special characters or symbols which may be displayed on the monitor to identify locations of points. For example, aircraft symbols to indicate the location of airports. Different sized markers
are used to show the classification of site attribute data.
Mean - The arithmetic average of a set of data values.
Memory - A portion of the OzGIS hardware used for the storage of data by the altering of the electrical state of the appropriate circuitry.
Menu - An itemized list of alternative actions which might be selected within OzGIS. Menus are displayed on the terminal. The terminal keyboard is used to enter selections from the options listed on the menu. The sequence of menu items which is selected controls the "flow" of the OzGIS program through its various tasks.
Monitor - The electronic equipment, resembling a colour television receiver, on which maps and graphics are displayed.
Nested Means - A quantization method in which classes are generated by dividing each variate range into two classes about the mean for that range. For example, the central class limit is set at the overall mean, then the upper and lower classes are each divided at the means of the two parts, giving four classes. This process may be repeated, giving eight classes.
Operating System - Computer software provided to facilitate usage of the various computer resources available within the OzGIS system.
Overlay - As a noun, overlay refers to graphic data written on top of the existing display. This is displayed on the monitor as though placed between the previous display and the viewer. Overlays generally are entered in the refresh memory in single bit planes. As a verb, overlay refers to the act of adding graphics data to a display by putting it "on top of" the previous display.
Palette - An array of coloured rectangles which is displayed on the monitor at certain stages of OzGIS. The palette shows a range of colours which are available for selection by the user..
Parameter - A general term referring to a physical characteristic which may be measured or quantified in some way, even though the precise value of that measurement may be unknown in specific instances. For example, age is a parameter of human beings.
Percentile - One of the set of 99 values which divide the range of a statistic into 100 equal sized classes.
Peripherals - Items of auxillary equipment added to a computer to enhance its performance. These include such items as disc drives, tape drives, and printers.
Pixel - The smallest, individually controllable, element (or cell) displayed as dots of colour on the monitor's screen. The monitor area is made up of lines of pixels. For each pixel, there is a corresponding location in the refresh memory for storing the data value associated with that pixel. This location is the smallest datum area which can be individually controlled by the software. See also Image and Location.
Point - A geographic feature which, for display purposes, may be described by only indicating its location as an x and y coordinate.
Polygon - A geographic area described by the line segments forming its boundary and the zone name which forms its surface. One or more polygons may be combined to form a zone.
Primary Variate - The set of statistical values characterized by a common name which is displayed on any given single variate map. Two such sets of values are displayed on a bivariate map. The primary variate is named at the top of the title, and its colour values are indicated in the rows of the legend. See also Variate.
Projection - The representation of a physical shape on the screen of the monitor according to a fixed mathematical coordinate system. Normally, a projection in OzGIS terms will refer to a method for presenting maps of geographic areas. See also Map Projection.
Quantile - Any of the specific values which divide the range of a statistic into equal sized classes. Some values have other special terms, i.e., if the range is divided into four classes, the boundary values are called quartiles. See also Percentile.
Quantify - To assign a number or quantity to an otherwise unnumbered entity. In particular, to assign a class number to a statistical value or zone name.
Quantization - The process of assigning class numbers to zones according to the value of the statistic for that zone. Viewed the other way, quantization is the process of putting zones into classes. Quartile - One of the three data values which divide the range of a variate into four equal sized classes. See also Quantile and Percentile. Raster - a term applied to image data. In particular data handled on a line basis.
Refresh Memory - The portion of the hardware (within the display controller) which holds the digital data necessary to continuously regenerate the colour monitor display. The cathode ray tube (CRT) of the monitor produces its display by electrically stimulating various phosphorus based compounds deposited on its face. The colours thus produced fade rapidly with time and must be continually "refreshed". The data necessary to perform this refresh correctly is stored in the refresh memory.
Region - A designated portion of a map displayed on the monitor. A region consists of one or more zones or parts of zones defined in some way (e.g. a circular region centered at a point on the map). The concept of a region is important when the displayed map consists of several geographic areas. In this context, a region consists of a window (geographic area) and its displayed viewport on the screen (screen area). See also Area.
Save - To store on disc (or magnetic tape) all the pertinent data regarding a map displayed on the monitor. The maps which are "saved" can later be fully regenerated with all details preserved.
Scatter Diagram - A two dimensional plot of points whose x and y coordinates are the values of the individual variates associated with those points. Scatter diagrams are displayed on the monitor in conjunction with bivariate maps. In this instance, each map zone is assigned a point on the diagram. The y-coordinate of the point corresponds to the value of the primary variate for that zone as displayed on the map. The x-coordinate of the point has a similar relationship to the secondary variate. In addition, the point will be coloured the same as its associated map zone. Scatter diagrams provide a visual method of assessing the correlation between the two variates displayed on the map.
Secondary Variate - The second set of statistical values which are displayed (along with a primary variate) on the map. The secondary variate is named at the bottom of the title. See also Primary Variate.
Segment - A set of connected straight lines defined to OzGIS by specifying the coordinates of their starting, intermediate, and end points, along with the names of the two zones on either side of the lines. Consequently, segments must represent a portion, or all, of the boundary between two zones. See also Line and Boundary.
Site - A geographic location that has associated attribute data. A site is defined by a name and fixed location e.g. a site could be a city or a retail store.
Standard Deviation - A statistical measure of the dispersion amongst a set of measured values. The standard deviation is mathematically equivalent to the positive square root of the variance of the sample on which the statistic is based.
Statistics - A general term referring to: 1) The branch of mathematics involved with performing certain analytical calculations regarding various relationships among sets of numerical data, and 2) The numerical results of such calculations. The height of an individual is data; the average height of a group is a statistic.
Status - The present condition of the software and hardware system, especially as to its progress toward the completion of the tasks at hand. The status messages are displayed as a response to typing interpretation of various abbreviated messages displayed on the terminal. The status messages are displayed as a response to typing an "S" command.
Terminal - An item of hardware comprising a keyboard for entering commands to the processor, and some means for the processor to return alpha-numeric messages to the user. The standard OzGIS terminal is the Digital Equipment Corporation VT100. This contains the necessary keyboard, and a cathode ray tube for displaying processor generated messages. Some OzGIS installations may also have a printer terminal for providing a permanent copy of the messages on paper.
Territory - a zone which has been formed by amalgamating bas zones e.g. sales territories formed from postcodes.
Text - Combinations of characters which may be specified by typing at the terminal. Lines of text may be displayed on either the terminal or the monitor in various fonts. See also Character, and Line.
Time Lapse Maps - A formatted set of maps concerning a geographic area and certain statistics associated with it as they have been collected over time. Time lapse files are used to display the time related changes in the statistical data by rapid and periodic changes in map colours corresponding to the statistics. For example, variations in population density, as recorded by the 1971, 1976, and 1981 census data, could be shown by changing the colours of the displayed map at one second intervals corresponding to the 3 sets of data.
User - The person who is interactively controlling the OzGIS system at the terminal.
Value - The number associated with a particular statistical item, as opposed to the colour associated with that item. For example, the zone might be coloured red to indicate four to ten beer drinkers per pub in that zone. The actual value of the statistic might be 9.4 beer drinkers per pub.
Variate - A measurable quantity which may take on any of the values within a given range, and which has associated with it a specified probability function describing the manner in which the permissible values are likely to occur. See also Bivariate, Primary Variate, and Secondary Variate.
Viewport - The rectangular area of the colour monitor face selected for displaying a specified item.
Window - The rectangular portion of a geographic map which is selected for display on the colour monitor.
Zone - A geographic area which is to be considered as a spatial unit. A zone is defined in terms of one or more polygons which form it. Statistically, a zone is defined in terms of a single value for each variate in question. This relationship of one variate value per defined geographic zone allows zones to be completely and uniformly coloured in a map display. See also Polygon and Variate.
Zone Name - An alphanumeric designation attached to the various computerized data associated with a zone. The zone name facilitates for the processor the task of relating various data items to the proper
zones.
The OzGIS system has a standard set of limits to various maximum counts. These correspond to array sizes.
30000 max no displayed zones+sites+lines
30000 max no values in attribute file (zones,sites,lines)
100 max no map regions
100 max no quantised zone geog files
100 max no quantised site geog files
100 max no quantised line geog files
100 max no line overlays
100 max no polygon underlays
100 max no marker overlays
100 max no name overlays
100 max no text strings displayed
500 max no polygons in a zone
5000 max no segments in a polygon
100 max no segments in a line
5000 max no vertices in a segment
20000 max no points in a fast display polygon
1000 max no zones per item in a combine file
256 max length of display system LUT (number colours)
50000 max no vertices in foreign segments data file
30000 max no zones that can be built from line segments
10000 max no vertices in object for spatial operations
5000 max no items in a text attribute file
15000 max no zones in a catchment
max no points in a catchment polygon
max no contours in a site catchment
120000 max no sitesXpoints for location allocation
50000 max no quantised zone, line or site handles
O'CALLAGHAN, J.F., SIMONS, L. and PALMER, J.A.B. (1980). A prototype system for interactive colour mapping. Proc. URPIS-8 (k. Davies (ed.)), Surfers Paradise, pp. 9.1-9.5.
SIMONS, L., O'CALLAGHAN, J.F. and PAINE, T. (1982). COLOURMAP - an interactive colour mapping workstation. Proc. DECUS (Digital Equipment Computer Users Society), Melbourne, Vol. 10, pp.1501-1504.
O'CALLAGHAN J.F., and SIMONS, L.W.J. (1983) COLOURMAP: An Interactive Colour Mapping System. Proc. First Australasian Conference on Computer
Graphics, Sydney.
O'CALLAGHAN J.F., and SIMONS, L.W.J. (1984). Map Display Techniques for Interactive Colour Mapping.
Henzell, O'Callaghan. A Sequential Line Simplification Algorithm based on Equivalent Height. CSIRONET Technical Report, May 1980
Robertson, O'Callaghan. The Generation of Colour Sequences for Univariate and Bivariate Mapping. IEEE Computer Graphics and Applications, February 1986.
Gerald Evenden. Cartographic Projection Procedures for the UNIX Environment - A User's Manual. USGS open-file report 90-284.
TIGER/Line Census Files, 1990 Technical Documentation / prepared by the Bureau of the Census. Washington: The Bureau, 1991.
Atef A Elassal. General Cartographic Transformation Package (GCTP), Version ii NOAA Technical Report NOS 124 CGS 9
J Sibert, 'Continuous-colour Choropleth Maps', Geo-Processing, (1980) 207-216.
'The Harvard Library of Computer Graphics Mapping Collection', Harvard University.
E Giamottic and P Puliafits, 'An Interactive Spatial Information System: A Tool for Regional Planning'; Proc IFIP 79.
J Dalton et al, 'Interactive Colour Map Displays of Domestic Information', Proc SIGGRAPH 79, Computer Graphics, Vol 13 No 2 ACM/SiGGRAPH.
A Robinson et al, 'Elements of Cartography', Wiley 1978.
D Des Jardins, 'Multi-Level Statistical Maps in Graphic Communication', Proc NCGA, Anaheim 1982.
"ACORD: AUTOMATIC COUNTOURING OF RAW DATA, Computers & Geosciences, vol. 8, no. 1, p. 97-101, 1982", by D.F. Watson.
L Cooper, 'Location allocation problems', Operatons Research 11, p 331-343 1963.
Goodchild and Massam, 'The transportation-location problem', Operations Research 20, 1969.
Tornqvist et al, Multiple Location Analysis, 1971.
Most of the examples are also available as saved map files. They require the standard example files supplied with OzGIS. All the files must be in the C:\OZDATA directory.
The examples can be displayed by using the File->Open menu
item.
You should start by looking at the OzGIS demonstration which consists
of a series of saved maps.
The demonstration is available on the net as the file OZDEMO.ZIP
The first example is a choropleth map of Australia, which is an example of a very common type of map to display attributedata like Census data, sales data, or government statistics.
Within WINDOWS run OzGIS.
Choose Map from the toolbar, and then DISPLAY ZONES FOR AN ATTRIBUTE FILE from the pulldown menu.
give the attribute file name as FEA (or select fea.att)
give the geographic file name as FEA (or select fea.geo)
You will have a default map with legend and distribution diagram.
The legend has the numbers of zones in each class on the left
and the class value ranges to the right of the coloured boxes.
You will often have a file of attribute data (such as population Census data) and a file of digitised boundary data for mapping (e.g. TIGER): We will look at data for Australia. There are two data files:
OZ-G.DAT are the digitised boundary data, (Australian Statistical Divisions)
OZ-A.DAT are the attribute data
Execute the OzGIS program.
Choose the IMPORT pulldown menu.
A menu will appear like:
IMPORT GEOGRAPHIC FILES
IMPORT ATTRIBUTE FILES
IMPORT A NAMES FILE
IMPORT A COMBINE FILE
IMPORT A DEVICE FILE
IMPORT A MARKER FILE
First enter the digitised boundary data:
Select the option to IMPORT GEOGRAPHIC FILES
The popup menu appears:
IMPORT A STANDARD FORMAT GEOGRAPHIC FILE
IMPORT NEW FORMAT SAS GEOGRAPHIC FILE
IMPORT OLD FORMAT SAS GEOGRAPHIC FILE
IMPORT A DLG-3 OPTIONAL FORMAT GEOGRAPHIC FILE
IMPORT A GINA FORMAT GEOGRAPHIC FILE
IMPORT A TIGER FORMAT GEOGRAPHIC FILE
IMPORT A DIME FORMAT GEOGRAPHIC FILE
IMPORT A DXF FORMAT GEOGRAPHIC FILE
IMPORT AUSLIG SEGMENTS FORMAT CENSUS BOUNDARY FILE
This enables geographic data to be read in in a variety of "standard" formats.
The test data is in the OzGIS standard format so choose
IMPORT STANDARD FORMAT GEOGRAPHIC FILE
A file open dialog now appears for you to specify a file name. Go to the \OZDATA directory.. You type in
what you want and then type enter:
give the input data file as OZ-G or select OZ-G.DAT
give the output geographic file as OZ
The data file will be processed, and a standard geographic file created.
The trace message at the top of the screen describes what is going
on.
Now enter the attribute data:
select the option to IMPORT ATTRIBUTE FILES from the Import pulldown mwnu.
A new menu appears:
IMPORT A STANDARD FORMAT ATTRIBUTE FILE
IMPORT A SPREADSHEET WK1 FORMAT FILE
IMPORT A DATABASE (SIMPLE) FORMAT ATTRIBUTE FILE
IMPORT A LAMM FORMAT ATTRIBUTE FILE
IMPORT USA CENSUS STF 1A FILES FOR TRACT/BNA
IMPORT USA CENSUS STF 1A FILES FOR BLOCK GROUPS
IMPORT ATLAS DATA FILES
The data are in standard form so:
Select IMPORT A STANDARD FORMAT ATTRIBUTE FILE
give the input data file as OZ-A
give the output attribute file as OZ
3. The data files are now entered so -
If you use the Files Manager to look in the directory \OZDATA you will find
that there are two new files there:
OZ.ATT is the attribute file and
OZ.GEO is the geographic file.
You (almost) never give a full file name within OzGIS - the system appends
a file extension to the name according to the file type.
The most common application is the display of data such as Census data as coloured polygons, usually known as a chloropleth map. Here the processes necessary to display such data are described.
Census data enables you to display maps that show where people live who are of different nationalities, ages, income groups etc. These maps are used for applications such as retail marketing to find where potential customers are located or for government planning to decide where to build facilities like schools.
You will probably have a file of attribute data (such as population Census data) and a file of digitised boundary data for mapping (e.g. TIGER): We will look at the data data for Australia. There are two data files:
OZ-G.DAT are the digitised boundary data, (Australian Statistical Divisions)
OZ-A.DAT are the attribute data
An example of entering these data files was given above.
Both the attribute file and geographic file are called OZ. Different types of files can have the same name.
Execute OzGIS.
Choose the Map pulldown menu and select DISPLAY ZONES FOR AN ATTRIBUTE FILE
give the attribute file name as OZ or select OZ.GEO
The data are now processed, the map is displayed, and the next menu appears. You now have a default map with legend and distribution diagram. The legend has the numbers of zones in each class on the left and the class value ranges to the right of the coloured boxes.
Now investigate some of the options:
Choose the option Attribute-> DISPLAY THE NEXT SEQUENTIAL ATTRIBUTE
Select the option to Attribute->SELECT AN ATTRIBUTE FROM A LIST.
Select Class-> CHANGE THE NUMBER OF CLASSES.
change the number of classes to 10.
Select the option to Class->CHANGE THE QUANTISATION METHOD.
Another menu will appear.
USE EQUAL VALUE INTERVALS
USE QUANTILES
USE SELECTED CLASS INTERVALS
USE SELECTED NUMBER OF ZONES PER CLASS
USE REFINED EQUAL VALUE INTERVALS
USE PSEUDO CONTINUOUS-COLOUR
USE THE MEAN AND STD DEVIATION METHOD
USE THE NESTED MEANS METHOD
USE THE NATURAL BREAKS METHOD
USE SELECTED PERCENTILES
USE SELECTED CLASS RANGE PERCENTILES
USE INTERACTIVE SELECTION OF CLASS INTERVAL,
USE EQUIVALENCE CLASSES
USE CURRENT CLASS RANGES
USE CURRENT NO PER CLASS
These options are very important as they enable the map to show the data in a way relevant to the purpose of the analysis.
For example, to select deciles:
Choose USE QUANTILES and set the number of classes to 10. The legend will now describe the 10 colours in the map.
Choose the option to Analyse->DISPLAY ATTRIBUTE STATISTICS.
Basic statistics will be displayed in a window for the displayed map.
Click "Quit" to remove the window.
Choose the option to Analyse->LIST ZONES FOR CENTROIDS SELECTED WITH BOX-CURSOR.
This will enable the current values for the displayed zones to be listed. A cursor will appear on the screen which indicates the bottom left position.
Use the mouse to select the first corner of a rectangle. A box
cursor then appears to select the other corner. All zones are
listed that have a minimum bounding rectangle (MBR) that intersects
the selected window.
Choose Control->Top Menu to return to the main menu.
You now have seen simple examples of the processes to produce maps.
1. you obtain your data as files in a standard format.
2. you usually set up a directory on the same disk as \OZGIS and put the data files there.
3. Use IMPORT from the top menu to read in the data files.
4. Use Map options to display.
But ......... this is very simple
You may want to do some data preparation before mapping.
You may have geographic data as line segments and need to form the polygons.
You may want to display other types of maps or diagrams.
You may want to output prepared maps to a printer, plotter or file.
and so on.
Bivariate maps enable you to compare two variables. For example
you may want to compare your sales figures with Census data for
the type of people you think are your customers.
First you need a bivariate device file to obtain a suitable colour set. Use Data->Display device file to see the default colour set. You will notice that the single variate colours are a sequence but the bivariate colours are mixed up. Use Data->Change device file and select one of the C256B*.DEV files, say c256bv1.dev. Use Data->Display colours again, and you will see that the bivariate colours are now a 2 dimensional sequence.
Select DISPLAY BIVARIATE ZONES FOR TWO ATTRIBUTE FILES from the Map menu.
Use attribute files LOWE1 and LOWE2 and geographic file LOWE (both attribute files can be the same i.e. you only need one file).
Note the form of the legend; the primary attribute (first file, top description) is the vertical part of the legend.
The main mapping menu will now appear on the toolbar:
These are the major groups of options and will be descibed in later chapters.
Use Control->Top Menu to return to the top menu.
This type of map is for applications such as deciding where to put shopping centres, where different symbols can be used for e.g. existing centres, centres owned by different retail chains and proposed new centres.
This example shows that type of map and also how the geographic data displayed on a map can be extended and modified.
Select DISPLAY ZONES AND SITES FOR TWO ATTRIBUTE FILES from the top menu.
Select DISPLAY SITES AS SIZED SINGLE COLOUR SYMBOLS
Use the LOWE1 and LOWE2 attribute files again, and the LOWE zones geographic file.
Give the sites geographic file as LOWE-S1.
This displays a file with polygons coloured for one attribute and symbols sized for the other. Now we can add more sites.
Choose REGIONS from the map menu, and then use DISPLAY MORE QUANTISED SITES ON A REGION. Give the next sites geographic file as LOWE-S2. Use symbol number 2 (number one is already used).
You will have a coloured zones map with different sized symbols
according to the attribute values and different symbols for the
two files.
Maps can be displayed that show geographic data without attribute data i.e. polygons, lines, names at points and symbols at points. Hence you can display roads, town locations, soil polygons etc.
Where the data are preclassified, feature codes can be used to subset the files for display.
For example, display some of the Hawaii DLG files. These files came from the USGS, and after some cleaning up, were entered as DLG-3 data and the polygons formed using BUILD TOPOLOGY FROM LINE SEGMENTS.
This example will display several of the files and show how feature codes can be used to subset the data displayed.
Select GIS from the top menu.
The next menu allows you to define a map according to the main file of geographic data that you have. You can add other data to the map as overlays
later:
DISPLAY LINE SEGMENTS FROM A GEOGRAPHIC FILE
DISPLAY MARKERS AT POINTS FROM A GEOGRAPHIC FILE
DISPLAY NAMES AT POINTS FROM A GEOGRAPHIC FILE
DISPLAY POLYGONS FROM A GEOGRAPHIC FILE
DISPLAY LINE SEGMENTS FOR FEATURE CODES
DISPLAY MARKERS AT POINTS FOR FEATURE CODES
DISPLAY NAMES AT POINTS FOR FEATURE CODES
DISPLAY POLYGONS FOR FEATURE CODES
Select DISPLAY POLYGONS FROM A GEOGRAPHIC FILE and use file HAWDLGWB, which is the outlines of the islands. Use any polygon number, give some text for the legend (e.g. "Islands") and use the no boundaries default.
The overlays menu will be used to add other geographic data:
OVERLAY LINE SEGMENTS FROM GEOGRAPHIC FILE
OVERLAY MARKERS FOR SITES IN GEOGRAPHIC FILE
OVERLAY NAMES FOR SITES IN GEOGRAPHIC FILE
UNDERLAY POLYGONS FROM GEOGRAPHIC FILE
OVERLAY LINE SEGMENTS FOR FEATURE CODES
OVERLAY MARKERS FOR SITES FOR FEATURE CODES
OVERLAY NAMES FOR SITES FOR FEATURE CODES
UNDERLAY POLYGONS FOR FEATURE CODES
DEFINE MAP REGIONS
CHANGE LEGEND
DISPLAY TEXT
SAVE DISPLAY AS A FILE
Select UNDERLAY POLYGONS FOR FEATURE CODES. Use file HAWDLGAB which is administrative boundaries. The file has feature codes in the range 900103 to 900108. Give the range as 900103 to 900103 and use polygon number say 4.
You will notice that a new menu item REMOVE POLYGONS UNDERLAY appears. A feature of the OzGIS system is that menus are dynamic and reflect the current status.
Select OVERLAY LINE SEGMENTS FOR FEATURE CODES. Use file HAWDLGRD which is roads. The file has feature codes in the range 2905001 to 2905041. Select a subset e.g. 2905000 to 2905020. Give the legend text as "roads".
Select OVERLAY LINE SEGMENTS FROM GEOGRAPHIC FILE. Use file HAWDLGST which is streams. Give the legend text as streams. The administrative boundaries go outside the island coastlines so you may want to redraw the island outlines by overlaying line segments for file HAWDLGWB.
Select OVERLAY NAMES FOR SITES IN GEOGRAPHIC FILE. Give the file HAWDLGWB. The polygon names will be displayed (the area numbers from the DLG file). Usually a points file would be used that has the actual names.
Select Text->TYPE IN A LINE OF TEXT, type in a title e.g. "HAWAII", and position it at the top of the map. Note that if you regenerate the map the polygons are drawn first, and then line segments, symbols and finally names. Within each type they are displayed in the order specified. If a mistake is made overlays can be removed.
You can change the view of the map: Select Region->SELECT WINDOW WITH THE BOX CURSOR.
Use "Top Menu" to return to the top level geographic map menu.
A similar set of options are available for overlaying data on
other types of maps. For example you may want to overlay roads
or town names on a Census data map.
Distributions, sorted values and quantisation results can be displayed as full screen diagrams for one or two attribute files. Scatter diagrams can be displayed for two files.
For example, to display two histograms for two attributes: Choose DIAGRAMS from the top menu. The menu enables you to choose the type of diagram:
DISPLAY VALUES HISTOGRAM FOR AN ATTRIBUTE FILE
DISPLAY QUANTISATION HISTOGRAM FOR AN ATTRIBUTE FILE
DISPLAY DISTRIBUTION HISTOGRAM FOR AN ATTRIBUTE FILE
DISPLAY VALUES HISTOGRAM FOR TWO ATTRIBUTE FILES
DISPLAY QUANTISATION HISTOGRAM FOR TWO ATTRIBUTE FILES
DISPLAY DISTRIBUTION HISTOGRAM FOR TWO ATTRIBUTE FILES
DISPLAY SCATTER DIAGRAM FOR TWO ATTRIBUTE FILES
We will display two attributes, so a bivariate device file should be used. Choose Data->CHOOSE DEVICE FILE and select a file e.g. c256bv2.dev
Choose DISPLAY DISTRIBUTION HISTOGRAM FOR TWO ATTRIBUTE FILES Use LOWE1 and LOWE2 files.
Next choose FEATURES from the main menu.
Now add some statistics lines:
Choose ADD STATISTICS TO DIAGRAM. A new menu appears:
DISPLAY MEAN & STD DEVIATION
DISPLAY MEDIAN
DISPLAY REGRESSION POLYNOMIAL (for scatter diagrams)
Try the DISPLAY MEAN & STD DEVIATION option (and others if you like).
You can change attributes and quantisation in the usual ways.
By now you will have realised that there are many options available
down a multitude of menu paths.
Some sample files are supplied with the system for Washington DC. These were supplied by the US Census Bureau, and would usually be obtained on CD-ROM.
The attribute file is WASHTRACT and was created by entering the first file off the STF1A CD-ROM (the original file was called STF1A0DC.DBF). This file contains about 40 of the 1990 Census variables extracted for tract/BNAs.
Three geographic files are supplied. These came from the CD-ROM files for Washington DC. The files for records type 1 (endpoints) and type 2 (shapes) were processed. The files were simplified (thinned) to reduce the size.
WASHTRACT was created by extracting census boundaries for the tract/BNAs with the IMPORT DATA FILES option, thinning with the PREPARE DATA FOR DISPLAY option, and finally using the BUILD TOPOLOGY option.
WASHRAIL is a lines file of railroads created by extracting for feature codes 200 to 252 in the data entry process.
WASHROAD is a lines file of all roads created by extracting for feature codes 100 to 148 in the data entry process.
These files can be used to demonstrate the use of overlays:
First select Map->DISPLAY ZONES FOR AN ATTRIBUTE FILE to display a zones map using attribute file WASHTRAC and geographic file WASHTRAC. This gives a standard choropleth map for 1990 Census data for Washington at tract/BNA level.
The Overlay menu offers options for several types of overlays:
OVERLAY LINE SEGMENTS FROM A GEOGRAPHIC FILE
OVERLAY MARKERS FOR SITES IN GEOGRAPHIC FILE
OVERLAY NAMES FOR SITES IN GEOGRAPHIC FILE
UNDERLAY POLYGONS FROM GEOGRAPHIC FILE
OVERLAY LINE SEGMENTS FOR FEATURE CODES
OVERLAY MARKERS FOR SITES FOR FEATURE CODES
OVERLAY NAMES FOR SITES FOR FEATURE CODES
UNDERLAY POLYGONS FOR FEATURE CODES
Now select Overlay->OVERLAY MARKERS FOR SITES IN GEOGRAPHIC FILE, use the same geographic file, select marker 1, give the legend text as TRACTS.
A series of markers will be displayed. The locations are the points within the standard zones/polygon file built with Prepare->BUILD ZONES so are the approximate centroids of the polygons.
Next select Overlay->OVERLAY NAMES FOR SITES IN GEOGRAPHIC FILE, and use the same geographic file in a similar way to display the tract codes. The names here are the zone names. You could of course use any file with different locations and names e.g. town names.
Now add a line segments overlay. Select Overlay->OVERLAY LINE SEGMENTS FROM A GEOGRAPHIC FILE. Use the file WASHRAIL to display railroads.
You could now do the same for the roads file washroads.geo. Try subsetting for feature codes as follows:
Select OVERLAY LINE SEGMENTS FOR FEATURE CODES. Use a different
line number each time and try a range 110 to 138 first to display
primary, secondary and country roads. Then try a range 140 to
148 to display neighbourhood roads. TIGER file feature codes are
defined in this manual.
The procedure to generate polygons from line segments can be demonstrated with most of the geographic data files:
First input the geographic data file and give it a temporary name:
Select Import->IMPORT GEOGRAPHIC FILES and then IMPORT A STANDARD FORMAT
GEOGRAPHIC FILE. Use the test data file LOWE-G and give the new file name as TEMP1.
Next line simplify the line segments to drop points:
Select Prepare->PROCESS GEOGRAPHIC FILES and then SIMPLIFY (THIN) LINE SEGMENTS. The input file is the one just entered i.e. TEMP1 and output the new one as TEMP2. Simplify according to the size of the final map on the screen
e.g. give a value of 100 to throw away a lot of the data points e.g. if you have a super VGA at 1024 X 768 you could use 750.
Now build the polygons structure from the lines.
Select Prepare->BUILD TOPOLOGY FROM LINE SEGMENTS from the top menu
The menu is:
BUILD ZONES FROM LINE SEGMENTS INTO NEW GEOGRAPHIC FILE
BUILD ZONES FROM LINE SEGMENTS INTO NEW DATA FILE
BUILD LINES FROM LINE SEGMENTS INTO NEW GEOGRAPHIC FILE
BUILD LINES FROM LINE SEGMENTS INTO NEW DATA FILE
The usual option is BUILD ZONES FROM LINE SEGMENTS INTO NEW GEOGRAPHIC FILE.
Give the input geographic file as the simplified file TEMP2 and output it as TEMP3.
Use the defaults for other questions.
Finally display the result (attribute file LOWE1 and geographic
file TEMP3) by using the Map->DISPLAY ZONES FOR AN ATTRIBUTE
FILE menu option.
Suppose you have entered a file that you know is UTM for zone number 20 and you want to convert it to Lambert Conformal. Conversion is two steps, UTM to Lat/Long and then Lat/Long to Lambert.
Use the menu options in Prepare->Map projections.
First write the UTM definition into the header of the file. Select CHOOSE FROM PROJECTION SET 1 from the menu, and then select U.T.M. and give the zone number. Then select WRITE PROJECTION DEFINITION INTO GEOGRAPHIC FILE and give the name of your file.
Your file will now be defined as UTM by having the file header updated.
Now choose TRANSFORM PROJECTION FILE TO LAT / LONG and give the file names to generate a temporary file (called say TEMP) in latitude / longitude from your original file.
Then use CHOOSE FROM PROJECTION SET 1 again and choose LAMBERT CONFORMAL CONIC.
Then using TRANSFORM LAT / LONG FILE TO PROJECTION will give you
the desired file in Lambert Conformal from the lat/long file to
a new file.
Suppose there are three breweries in Australia and you want to know a good place to build another one.
Select Application->Site Location Allocation.
Give the geographic file name as OZ and the attribute file as OZ.
Choose an appropriate attribute - obviously "Beer consumption", and chosse 4 sites.
Give a name for the generated geographic file, say BREWERY
A solution will be displayed.
Now select Site->Give site a name and give the fourth site the name NEW BREWERY
Now for each of the existing sites (SITE001 to SITE003) choose Site->Digitise fixed location for a site and choose a location with the mouse.
You have now specified the locations of the three existing breweries and fixed them at those locations. The new brewery site is still mobile.
Finally use one of the algorithms from the Algorithm menu to generate a solution.
The solution can be used for further mapping.
Select Applications->Site catchment definition.
Give the geographic file as CANBL81 (Canberra local government areas)
Select Define-> INCLUDE SITES FROM A CATCHMENT FILE
Give the catchment file as catch
A set of site catchments in Canberra will be displayed for a set
of catchments that were previously defined.
Notes
You need a geographic zones file, and an attribute file of demographic data (typically Census data).
The attribute used will relate to the project e.g. to site child-care centres you may use 0 to 4 year olds.
The base map zones cannot have any missing data.
The following demonstration files are supplied:
Suppose you want to analyse some shopping centre sites in Canberra and you have a geographic file of boundaries called CANBL81, a geographic file of suburb names called ACTSUBUB and a file of Census data for the zones called CANBL81.
Select Applications->Site catchment definition.
The catchments are defined relative to a base map, and there is the concept of a current set of sites being worked on. So give the geographic file as CANBL81. The base map is displayed.
First of all the shopping centre catchments have to be defined, so select Define
The following menu appears:
ADD A NEW SITE
DELETE A SITE
RENAME A SITE
REPOSITION SITE LOCN, NAME OR SYMBOL
MODIFY SITE CONTOURS
SEARCH GEOG FILE FOR SITES INSIDE A CONTOUR
CHANGE DISPLAYED REGION
TEMPORARYILY OVERLAY OTHER CATCHMENT FILE ON BASE MAP
OVERLAY GEOGRAPHIC FILES ON BASE MAP
DISPLAY ALL CURRENT SITES
INCLUDE SITES FROM CATCHMENT FILE
INCLUDE POINTS FROM GEOGRAPHIC FILE
INCLUDE POLYGONS FROM GEOGRAPHIC FILE
DISPLAY TEXT
OUTPUT TO CATCHMENT FILE
OUTPUT TO CATCHMENT FILE AND EXIT
Next display the suburb names by selecting Define->OVERLAY GEOGRAPHIC FILES and then OVERLAY SITE NAMES FROM A GEOGRAPHIC FILE. Give the file name as ACTSUBUR
The names are to help "navigate" so are not really necessary. You might also display roads (if you have the data).
You may also want to use the CHANGE DISPLAYED REGION option to change the part of Canberra that is displayed.
Now a new set of catchments can be defined (you can read in an old set) Select ADD A NEW SITE, which displays the menu:
ADD NEW SITE, CURSOR POSN
ADD NEW SITE, TYPED POSN
Sites are initially defined as circles. You provide a name, the radius of the circle, and a weight. Suppose it has been decided as a starting point the 75% of people living within a 5KM radius of a shopping centre will buy all their groceries there. So select ADD NEW SITE, CURSOR POSN for each site
You can define several sites and modify them in several ways e.g. add more contours.
Finally use Defgine->OUTPUT TO CATCHMENT FILE to store the site definitions.
Now the first version of the catchments have been defined, the proportions of the underlying base polygons that are within the contours can be calculated for each site and the weights applied.
Select GENERATE CATCHMENT FILE ZONES AND WEIGHTS
Give the names of the base zones geographic file as CANBL81 (it could be something else) and the name of the catchment file. The polygons and the contours are now intersected to find the areas of the common parts and the catchment file is updated for the list of zones and weights for each site.
Now the mapping data has to be output to files for mapping: Select Assemble, which gives the menu:
INCLUDE SITES FROM CATCHMENT FILE
CHANGE SYMBOL DISPLAY LOCATION
CHANGE NAME DISPLAY LOCATION
CHANGE DISPLAYED REGION
OUTPUT ZONES AND WEIGHTS TO COMBINE FILE
AMALGAMATE ATTRIBUTE DATA FOR COMBINE FILE
OUTPUT GEOGRAPHIC FILE FOR SYMBOLS AND CONTOUR DISPLAY
OUTPUT GEOGRAPHIC FILE FOR SITE NAMES AND OFFSET LINES
First select INCLUDE SITES FROM CATCHMENT FILE and give the catchment files as CATCH (you could input several files). This is an example file of defined catchments.
Now generate a geographic file for mapping the sites by selecting Assemble->OUTPUT GEOGRAPHIC FILE FOR SYMBOLS AND CONTOUR DISPLAY and giving a file name as say SITES.
Then select Assemble->OUTPUT GEOGRAPHIC FILE FOR SITE NAMES AND OFFSET LINES and give a file name, say NAMES.
Now accumulate the attribute data for the sites:
First select Assemble->OUTPUT ZONES AND WEIGHTS TO COMBINE FILE and give the file as SITECOMB (dont overwrite the example file COMB!). The combine file will contain the list of zones for each site and the weights.
Select Assemble->AMALGAMATE ATTRIBUTE DATA FOR COMBINE FILE
The attribute file is that for the base zones L81 and the combine file is SITECOMB. Give the output attributes as SITES.
You can now map the site data, so return to the top menu and select Map
You now have the two main files for mapping, a points file called SITES and the related attribute file SITES.
You could now select Map->DISPLAY SITES FOR AN ATTRIBUTE FILE to map the data. However, you can also display the original base map data at the same time: Select Map->DISPLAY ZONES AND SITES FOR TWO ATTRIBUTE FILES
The map is now displayed, with the site symbols on top of the base map.
Now add the contour lines by selecting Overlay-> OVERLAY LINE
SEGMENTS FROM A GEOGRAPHIC FILE. Give the file as SITES.