P3D Bowl and stereo lies

["H a r o l d B a i z e" <baize@xxxxxxxxxxxxx>]

Excuse the provocative subject line. I was intrigued by Larry 
Berlin's description of a bowl effect when viewing a "flat" 
pair in a red button viewer. I created a flat pair slide to 
demonstrate stereoscopic perception. It is a 7-P slide of a 
toy dinosaur where the two images are identical. I made a 
second slide with stereo. When I view the flat slide in my 
Kodaslide II (widened to 7-P by Dr. T-- hey that rhymes) I 
do not detect any distortion.

Here is the interesting part for me. I sometimes hand the viewer 
to friends with the flat dinosaur slide, and say "Wow, look at 
this 3-D slide!" So far not a single person has objected and said 
that it is NOT 3-D. When I tell them it is flat they just seem 
dumbfounded. Ok, I know it isn't nice to deceive people, but I was 
trained as a social psychologist and old habits are hard to break.
The response of my "subjects" causes me to wonder whether people 
are sincere when they praise the depth of stereo slides. 
As a caveat I must admit that the flat dino photo has a lot of 
non-stereoscopic depth cues, and to the uninitiated it may well 
appear to have true stereo depth.

Perhaps I should create another set of "flat" and "stereo" slides 
where the image contains few or no depth cues. Perhaps a random 
dot pair as in the classic Julesz studies.

Harolddd


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