Re:weighting depth cues

[T3D Larry Berlin <lberlin@xxxxxxxxx>]

Peter Abrahams writes:

>The many cues to information on relative depth of an object in a visual
>field are discussed in Howard & Rogers, _Binocular Vision and Stereopsis_.  
>A distinction is drawn between spatial cues arranged in parallel, where any
>one cue is sufficient (direction of a sound), or in series, where all cues
>are needed (judging relief of a surface from motion parallax of the
>movement of the head).  In a parallel cue system, the cues can conflict
>with each other.  ..................
>.........., one study included the view that there is no consistent theory
>for these phenomenon, but instead a 'bag of tricks which provides
>particular solutions in particular situations'.  

Fascinating. Reality is a constantly swimming mix of both parallel
and series elements. Today we would include the description of *digital*
which can be subtlely different, but akin to sequential parallel events
provided unique meaning by recognition of complex patterns. The cross
checking process between different senses can go quite deep when there is
either a choice to do so or a particular stimulus for closer examination.

>Page 448, disparity-perspective interactions, is more relevant to
>discussions of stereo photography, and includes Schriever's 1924 study
>using stereo photographs with reversed disparity, which showed that depth
>was judged more from perspective than disparity.  

Is this the same as the inside out face problem? If so, the
conclusions are incomplete and I can think of circumstances where
disparities outweigh perspectives. It's important to maintain a reliable
measure. This quality is subject to the scale of familiarity, with the more
familiar requiring less verification by disparity, and thus easily fooled.
Or the least familiar depending almost entirely on disparities in a search
for definition. In an attempt to answer the persistent question, what is
that *thing*, the mind seeks in the disparity structure for clues to identity. 

Larry Berlin

Email: lberlin@xxxxxxxxx
http://www.sonic.net/~lberlin/
http://3dzine.simplenet.com/


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End of TECH-3D Digest 184
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