[photo-3d] Re: First P3D use of term

[Jim Crowell <jcrowell@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx>]

>>>> If the subject is large and/or close, such that parts of the
>>>> subject are occluded by the frame edges, you must consider the
>>>> stereo window, the stereo pyramid...
>>> 
>>> Please elaborate on the term, John!
>> 
>> I'll take a guess... The field of view in stereo photography
>> is in the shape of a pyramid.  A stereo pyramid!  Actually,
>> it is a truncated rectangular pyramid.  The top is the stereo
>> window.  From there it extends to infinity.  The vertices are
>> defined by the 4 corners of the stereo window.
> 
> Believe it or not, there's a name for this truncated pyramid shape
> ... frustum.  This comes up a lot in computer graphics in describing
> the volume of space that can be displayed in a 3D model.

...except in photography it really is a pyramid instead of a frustum, since
you _can_ see stuff in front of the stereo window...

-Jim C.
-------------------------------------
Jim Crowell, Ph.D.
Dept. of Psychology
Cognitive/Experimental Group
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Ohio State University
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