






                     Custom Map Databases and Map Overlays

              "Maps   and   Legends,  The  Cartographer", version  2.0
         includes  a  feature to let you create and use additional map
         coordinate  files.   The  "Overlay..."  option of the "Files"
         menu  allows  you  to select and draw maps from files you can
         create.   In  this  section  the  format  of  these  files is
         described   together   with   examples  of  how  to  use  the
         "create.ttp"  utility  to  generate additional map coordinate
         databases.   The  "Overlay" feature is very general.  With it
         you  can  draw almost anything on your maps, including roads,
         cities,  country  boundaries, time zones, or satellite ground
         tracks, in any of the available projections.

              The  "Overlay..."  option under the menu item "Files" is
         enabled  whenever  you  draw  a  map  in any of the "Maps and
         Legends"  projections.   If you select this option, the "file
         selector"  will appear showing you the directory of all files
         with  the ".INT" extension in the "DAT" folder of the program
         disk.   Selecting one of these files and clicking on the "OK"
         button  will load and draw it according to the projection and
         scale  of  the map drawn most recently.  You can use the file
         selector  to  search  other  folders  or  even other disks by
         clicking  on  a  folder,  clicking on the close button of the
         directory  window,  or  by  editing  the  pathname  above the
         directory  window.   When you have selected the file you wish
         to  plot, just click on the OK button.  Any number of overlay
         files may be added to any map, using different line widths or
         pen colors, as desired.



                          Format of the ".INT" file.

              A point on a map is described by latitude and longitude.
         In  addition,  if  you  want  to describe boundaries or paths
         between  points  you need to specify whether or not to draw a
         line  to  this  point from the previous one.  Together, these
         three  pieces  of  information,  whether  or  not to connect,
         latitude, and longitude, form one coordinate set in the "Maps
         and  Legends" data files (".INT" files).  In this section, we
         describe  the  format  of  the ".INT" file for the benefit of
         those  who  wish  to  generate  their  own  files  from other
         databases.

              In  "Maps and Legends", map position items are stored on
         the disk as an array of integers organized as

              {(Connect?) (10 * longitude) (10 * colatitude)}

              Points  are plotted in the order that they appear in the
         file.  The first integer of every coordinate set, "Connect?",
         is either zero or one, and specifies whether or not to draw a
         line  to  this  point  from the previous one according to the


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         code  0  =  NO,  1 = YES.  The second item of each set, "10 *
         longitude"  is  an  integer  which  is  ten  times  the  east
         longitude  of  the  point.  It must have a value in the range
         from  0  to  3600.   The  last  item, "10 * colatitude" is an
         integer  in  the  range 0 to 1800.  Its value is 10 times the
         colatitude of the point.  Colatitude is like latitude, but is
         measured  from the North Pole.  The colatitude of the equator
         is   90  degrees  and  the  south  pole  is  at  180  degrees
         colatitude.   The  maximum allowed size of any ".INT" file is
         12000   bytes.    This  is  enough  room  for  2000  sets  of
         coordinates,  each  set consisting of these three integers (2
         bytes  per  integer).   A  ".INT" file may be as small as one
         coordinate set (6 bytes).



                           The "CREATE.TTP" Utility

              While the ".INT" file format is a convenient one for the
         computer,   it   is   not  so  convenient  for  people.   The
         "CREATE.TTP"  utility  is  included  with "Maps and Legends",
         version  2.0,  to  provide  a way to generate coordinate data
         files  quickly  and easily from an ASCII file.  With the help
         of  "CREATE" you can use any word processor or text editor to
         enter  coordinate  sets  for  "Maps  and  Legends"  to draw.
         "CREATE"  takes  as  input an ASCII file and creates a ".INT"
         file from it.

              The  format  of the ASCII file for "CREATE" is flexible.
         The file should contain lists of numbers in the order:

             CONNCT?1 LATITD1 LONGITD1 CONNCT?2 LATITD2 LONGITD2

         where  CONNCT?  has  the  same  definition as CONNECT? in the
         ".INT"  file,  LATITD  and  LONGITD  are  the  latitude  (not
         colatitude)  and  longitude  of  the  point.   The only other
         requirement  on  the  format  of  the file is that no numeric
         ASCII  character can appear in it unless that numeric is part
         of some "CONNCT? LATITD LONGITD" set.  Consecutive values can
         be  separated  by any number (at least one) of any characters
         except numerics (and single decimal points).

              "CREATE.TTP" does some simple consistency checking as it
         processes  its input file to detect any major format or range
         errors.   For  example,  if the value of CONNCT? is something
         other  than  0  or  1  (".0"  or  "1.000000",  etc.  are also
         permitted),  an  error message will appear.  You must correct
         the  error  before  the  rest of the file can be processed by
         "CREATE".   Latitude  and  longitude can be given as positive
         (north latitude, east longitude) or negative (south latitude,
         west  longitude)  numbers  with  or  without decimal points.
         Latitude should be in the range from -90 degrees (south pole)
         to 90 degrees (north pole).  Longitude should be in the range
         from  -180  degrees to 360 degrees.  West longitudes can have
         values  less  than 0 or more than 180, whichever you prefer.
         Decimal  values  will be rounded to the nearest 0.1 degrees.


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         You  can  include any comments or other labels in the file as
         long  as  they  do not contain any numeric characters.  Below
         are  some examples of text files acceptable to "CREATE" which
         describe the border of the state of Wyoming.


              Example A  This draws the Wyoming state border.

         0  45  -111.05  1  45  -104.05 1 41 -104.05 1 41 -111.05 1 45
         -111.05

              Example B  This also draws the Wyoming state border.

         0,45.00,-111.05 Northwest
         1,+45.
          ,-104.05 Northeast
         1+41-104.05+1+41-111.05 Southern border
         1      45.0000000000     -111.05  Wyoming complete !


              To  run "CREATE", double click on the file "CREATE.TTP".
         When  the  parameter  dialog  appears,  enter the name of the
         ACSII text file that you wish to process and click on "OK" or
         press  return.   The program will list each coordinate set as
         it    is    processed.     The    diagnostic   messages   are
         self-explanatory.  The output file made by "CREATE" will have
         the  same  name  as  the  input  file,  but  with  the ".INT"
         extension.   It  is  unwise  to  use  ".INT" as the file name
         extension  of  the text input file.  Once created, the ".INT"
         file is ready to be used with the "Overlay..." option.


              As  an  example,  to  help  you  to get started, we have
         included  the  file  "ORBIT.TXT",  a  sample  ASCII text file
         containing  hourly  position coordinates for the ground track
         of  a high altitude satellite (SCATHA) over a two day period.
         Run  "CREATE.TTP"  on  it  to create "ORBIT.INT".  The ground
         track  is  a  series  of loops over the equator (near Central
         America  for  this  period) that move east by about 5 degrees
         per day.



         Special Note:

         The earth is round, and there are many different ways to draw
         "straight  lines"  between two points on the earth, depending
         on  the  projection  you  choose.   When  drawing  a map, the
         program  does  some checking to see whether it is drawing the
         "shortest"  line.   As  a  result, if you want to draw a path
         between   two  widely  spaced  positions,  you  may  find  it
         necessary to include some intermediate "waypoints" to get the
         line drawn the way you want it.





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