Charles Piper on PePax fallacy

[P3D Dr. George A. Themelis <DrT-3d@xxxxxxxxxxxxxxxxxxxxxxxxxxx>]

Of course, Charles Piper has a lot to say about this.  On Installment 
#57 he starts by saying: "A fairly widely held, but incorrect, theory
holds that focal length and baseline should be kept proprtional, e.g.
both increased in the same ratio.  This installment will attempt to
clarify the subject."

He goes on explaining the concept of orthostereo and deviations from
orthostereo, effect of baseline, effect of focal length and permissible
perspective distortions.

A simple experiment to try: "With a stereogram projected on a screen
start at the back of the room and walk toward the screen.  As you do
so, note that depths become swallower.  For example, a stereo portrait
shot with a Realist and then viewed at 25 feet on a 6 foot screen will
appear to have exaggerated depth (long noses, exaggerated bosoms etc).
If you will now approach the screen, at some point the shapes will look
correct.  This is the orthostereo point..."

Perspective distortions are OK "if all subject matter is at about the
same distance from the camera, or if the objects are not so familiar."

That and more on Charles Piper's "The Technical Page", available by
the author.  I do not see his address listed in Stereo World and don't
know if he wants his address distributed in public (here).  I don't
even know if he minds that I quoted him expensively here. I hope he
doen't! -- George Themelis


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