Re: Dual camera convergence points

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

>intentionally creating a convergence point.  Is it recommended that the
>cameras be positioned perfectly parallel?

Yes, it is.  Tilting the cameras will create keystone distortion in a
parallel viewing/projection system.  If the viewing/projection system was
similarly tilted then there would not be any distortion.  However, most
systems are parallel.

>(Isn't there an intentional convergence point at 30 x the base, more or
>less 7 feet, built into the Realsit?)

This is built just by a parallel displacement of the centers of the image 
area in relationship to the centers of the lenses (simple geometry) and
_not_ by tilting the lenses.

The above are facts, I believe, and theory.  In practice (here comes
an opinion) you could converge the lenses and see no effect on the final
stereo image.  I think that such convergence has been used in motion
pictures to place the stereo window appropriately.  So you can do the same
as long as the distortion does not become a problem.

George (always translates a single camera parallel but he occasionally tilts
the twin cameras especially with longer lenses; when he handhelds a single
camera then he usually marks the same object in the center which means that
the lens is tilted between exposures; yet distortion has never been a
problem)


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