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From: jjc@sun1.MAYO.EDU (Jon Camp)
Newsgroups: comp.graphics
Subject: Re: 3-D perceptual abilities
Keywords: TV 3-D graphic
Message-ID: <1104@nic.MR.NET>
Date: 31 Jan 89 16:13:32 GMT
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Reply-To: jjc@sun1.UUCP (Jon Camp)
Organization: Mayo Clinic, Rochester, MN
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1) As Benie Cosell posted, 3-D perception is much more than stereopsis.  It involves parallax, focus, accomodation, obscuration, perspective, memory, a great many other functions which I am not aware of and most likely some that no one has ever measured.  In our everyday lives, stereopsis is not even the primary means of depth perception.   Stereopsis IS, however, relatively inexpensive to simulate, and is therefore the only contact most people have with  "3-D display". 

2) Early studies of stereopsis indicated that as many as 30% of the population were "stereo-blind".  More recent studies put the figure closer to 10%.  I have never heard the 80% figure before, and I doubt that we would see stereo effects (of ANY quality) on broadcast TV if that were the case.  Our own informal survey of employees at the BRU (mostly medical imaging people, but a few secretaries, administrators and technicians as well) found only one "stereo-blind" individual out of 30 tests - he had only o



ne good eye.  We note that the earlier studies required the subjects to make the depth/no depth decision very quickly whereas we allowed our coworkers to take as much time as they needed - so MAYBE **WARNING - unfounded wild theory ahead *** there is more than one mechanism of stereo perception, some instantaneous, some requiring the use of memory.

3) The common wisdom is that stereopsis is most effective within the reach of our hands.  My personal experience is that this is true.  I suspect it is possible to prove that beyond a certain distance it is physically impossible for our visual apparatus to sense any difference between left and right views. 

4) As one who has experience viewing stereo and other 3-D representations, I wish to report that stereopsis alone gives me a sensation of "viewing fatigue", possibly because stereo so vividly presents SOME depth cues while perversely witholding others.  This is a personal experience, NOT a rigorous criticism of stereoptic display.


This is more than enough for a posting, but I can talk indefinitely about perception, display, graphics, imaging, (man,woman,life,death,infinity...) and will if anyone cares to continue this by email.



Jon J. Camp		- Free advice, worth the price.
3-D Display Group
Biodynamics Research Unit
Mayo Foundation
jjc@bru.mayo.edu