P3D Keystone

[fj834@xxxxxxxxxxxxxxxxxxxxx (Dr. George A. Themelis)]

>I'd be curious to see what this Keystoning looks like.
>
>I seem to remember a post describing a new stereo photography manual/guide
>that you were offering for sale. This sounds like something I should be
>reading. At the convention, I thumbed through a copy Reel 3-d's "Stereo
>Photography" by Frizt G. Waack. It's sort of a nuts and bolts guide to many
>of the technical aspects of the craft. Is your book similar?

The closest to this description is a series of "Tutorials in Stereo
Photography" which was published in our newsletter and it is offered for
sale in a bound volume for either $15 (all newsletters) or $10 (only the
tutorials).  All profits from these sales go to our stereo club.  I plan to
continue this series with more advanced concepts, starting in September
this year.  Annual subscription is $15.  I will post more details in
sell-3d in a month or so.

However, my style is nothing like Waack's.  I prefer to write in simple
terms trying to explain how things work, without using any math, if
possible.  For example, you asked about "keystone distortion".  It helps if
you know the shape of a keystone or if I could draw an ASCII drawing!

Imagine a rectangular.  If you go to the left of it and point the camera,
the side of the rectangular closer to the camera will be larger than the
side further away.  If you go to the right of it then the opposite side
will be larger.  Hence the right and left images do not match and you have
vertical misalignment in the stereo pair.  This will happen if you converge
the camera.  If you keep it parallel, you don't have this problem.

BTW, Pennsylvania is known as the Keystone State because it resembles a
Keystone and the company Keystone got its name from PA.

George Themelis


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