Re: The Keystone Effect

[P3D Morris M. Keesan <keesan@xxxxxxxxxxxxx>]

Rev. Robert B. Linnstaedt wrote:
>In a message dated 96-05-07 Dr. G. Themelis wrote:
>
>>I think you are confusing keystoning with hyperstereo or something else...
>>Keystoning will introduce some distortions and it should be avoided.  It has
>>the advantage of allowing you to set the stereo window at will without
>>masking and loss of image area.
>
>What!! ?? !! The term has to do with projection and perspective distortion.
>
>As I understand, the keystone effect or "keystoning" refers to distortion
>created by projection onto a screen not parallel to the image plane.

This may be true, but in discussing stereo photography, "keystoning" usually
refers
to the same kind of distortion created by having the lenses pointing inwards
instead
of parallel to each other, so that when you mount the two images parallel to
each
other, you experience HORIZONTAL distortion of the same sort.  Angling the
lenses
inward does allow control of the window, but at the cost of keystone distortion.

----------------------------------------
Morris M. Keesan -- keesan@xxxxxxxxxxxxx


------------------------------