Double Image Random Dot Stereograms

[P3D Harold R. Baize, Ph.D. <baize@xxxxxxxxxxxxx>]

Greetings 3-D fellows,

I recently had on off list conversation with Dr T on whether or not
there is such an animal as a Double Image Random Dot Stereogram 
(DIRDS) . In summary, the work that got this
whole "magic eye" phenomenon started was with traditional
double image stereograms. In the early sixties 
Bela Julesz used stereo pairs made of random patterns of
dots that had shapes displaced within the dots to create 
stereoscopic depth. His research proved that stereoscopic
information in isolation and without any other form of depth cues
can produce depth and shape perception.
One of his co-workers (Christopher Tyler) developed the SINGLE
image random dot stereogram in 1979 and published the algorithms to
generate them in 1990.

I want to make true double image random dot stereograms because
I would like to do some research on individual differences in
stereoscopic perception, and how it varies with the shape of the object. 
So I need to isolate stereoscopic perception from other cues, as 
Julesz did thirty years ago. 


Dr. T told me that all you need to do is copy a SIRDS twice and
mount it with the correct displacement to produce the stereoscopic 
image. It sounds like a wonderful idea to be able to copy 
the same SIRDS in the left and right channels and project or view 
them to produce a stereoscopic image. I will have to try that. 
However, I'm sure that would produce lower resolution than a true 
DIRDS, since each eye would also be viewing dots that contribute to the 
image of the other half of the pair. 

If anyone knows of an existing Intel/MS-DOS/Win program that can 
generate DIRDSs I would be very grateful for the information.

Thanks for your help.

Harold Baize
baize@xxxxxxxxxxxxx
 
Harold R. Baize, Jr. Ph.D.                       
University of California, San Francisco
Child Services Research Group             
44 Montgomery St. Suite 1450            
San Francisco, CA 94104 


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