

                        ╓────────────────────────────╖
                        ║                            ║
                        ║      PERSPECTUS, v1.0      ║
                        ║                            ║
                        ║       by  Alan Meiss       ║
                        ║                            ║
                        ║       copyright 1993       ║
                        ║                            ║
                        ╙────────────────────────────╜




-= Introduction =-

Stereoscopic images are two-dimensional pictures that create the illusion
of depth.  In standard form, such as the stereoscopic cards popular at the
turn of the century, two images are present side-by-side, each shifted
slightly in perspective corresponding to the distance between a pair of
human eyes.  When the image is viewed properly, the eyes superimpose the
two images and are tricked into perceiving an image with depth.  Perspectus,
however, is able to generate stereoscopic images from designs the user
creates on a single image field.  The program generates a background field
of random dots, like snow on a tv, and then perturbs the dots to create
an image with multiple planes of depth.  What appears to be a two-
dimensional field of random dots becomes an image with depth when properly
viewed.


-= System Requirements =-

Perspectus requires at least EGA graphics capability and a mouse to run.


-= How to Use Perspectus =-

The first portion of the program consists of a simple paint program for
creating images to later be processed.  The paint commands are mouse
driven as in most familiar programs, with commands available for writing
text, erasing, drawing points, lines, boxes, circles, copying areas, and
painting.  Moving the mouse cursor over a grey command button will identify
its use, and clicking the mouse on the button will activate it.  Some
special notes about the commands and features:

   ■ The currently selected command will highlighted in white on its
     command button.

   ■ The currently selected drawing color will be marked by a square
     on its command button.

   ■ The large letter at upper left shows how large letters you type
     with the alphabet command will appear.  Click the left and right
     arrow buttons to increase or decrease the letter size.

   ■ To type text, click the "A" button (for alphabet), and then click
     with the mouse cursor on the upper left corner where the text
     should be placed in the drawing field.  You may type characters
     until out of drawing space.

   ■ You cannot draw a circle extending outside the drawing area.

   ■ The paint command works as follows: clicking on a blank (black)
     point on the drawing area with fill the black area bounded by
     the currently selected drawing color.  Clicking on a colored point
     will fill all contiguous areas bounded by black with the currently
     selected color.  Use caution when painting!

   ■ Each color corresponds to a level of depth in the final image, with
     white shallow, yellow a bit higher, and so forth.

The larger command buttons at the bottom of the screen perform special
functions.  "New" will erase the screen after confirming your choice. "Save"
and "load" let you record and later recall your drawings from files stored
on disk, with filenames you may specify.  "Process" will generate a stereo-
scopic image from your design.  "Help" displays this information file, and
"Quit" leaves the program.


-= Processing the Image =-

Selecting the "Process" command will proceed to the most important part of
Perspectus, the creation of a stereoscopic image.  The image is displayed
as it is created, with the background drawn first and the appropriate
perturbations then added to generate the depth image.  Click the mouse when
the image is complete to activate the command buttons.


-= How to View the Image =-

The images created by Perspectus are a bit tricky to view, and it may take
some practice to see the illusion properly.  Rather than looking at the
screen itself, focus your eyes past the screen as if you were looking at a
more distant object.  Focus past the screen in this way until you see
three dots above the screen.  There are actually two dots, but each eye
sees the two dots independently.  You will see three dots when you can
overlap your left eye's view of the right dot with your right eye's view
of the left dot.  Some examples:

Normal view:          o          o

Not quite:     o         o    o          o

Almost:          o         oo           o

Got it!:          o         o          o

When you see 3 dots, hold this view and glance down to the image.  You
should be able to see the depth image, with each color corresponding to a
layer of depth.  If you see a depth image but letters are not distinct,
check and be sure you are focusing your eyes at the right distance by looking
for the image of three dots at the top.  It's easier for some people to see
the image than others, so don't be frustrated if you have trouble viewing the
illusion; try it with a friend and see if they can view the image.


-= Tips and Tricks =-

   ■ There is a demonstation picture file named PERSPECT.SAV you can
     load to show a range of shapes.

   ■ Drawing with a "low" color on top of a "high" color will create the
     illusion of cut-out pieces in the resulting image.

   ■ The illusion is still visible when the image is printed.  Try using
     a print-screen or image capture program to print a paper copy of the
     display; just after the image has been generated and before you click
     the mouse to display the command buttons is the best time to do this.


-= About the Program =-

Perspectus was written in Turbo Pascal, January 1993, and is released to the
public as shareware.  You may freely copy and distribute the program, but
if you enjoy it and/or find it of use, please send a suggested donation of
$5 to the author at the address below.  Doing so also lets you freely copy
and publish any images you generate with the program, and will encourage the
author's work on more such programs.  Thank you for using Perspectus!

Alan Meiss
2626 Parkwood Drive
Speedway, IN  46224

Internet email: ameiss@gn.ecn.purdue.edu




