In article <406c9f6e$1@news.povray.org>, "Harold" <bai### [at] 3dculturecom> 
wrote:

> Only if you have limited range of depth. Toe-in will produce
> keystone distortion that will make the images difficult to
> view.

What I'm doing does not produce keystone distortion. I'm talking about 
modifying the direction vector, while leaving the right vector alone. 
The result is basically the same as cropping images from parallel 
cameras, and seems to be a lot easier to focus on, as well as making 
better use of the image space.


> There is a physiological basis for the 30:1 rule. At about
> 30 times the distance between our eyes (2.5 inches * 30
> = 70 inches) our eyes cease to converge (cross as you say)
> and are essentially parallel.

And if two cameras are rotated to converge at a point at a distance 
greater than 30 times the separation of the cameras, the keystone 
distortion will be very small, because the cameras will be essentially 
parallel. For most such scenes, rotating the cameras will neither give a 
benefit nor cause a problem. When focusing on nearer objects, rotating 
cameras should simulate what the eyes really see more closely.


> It would be interesting to imagine a stereo
> viewing system where the image planes rotate to stay oriented with
> the eye as they converge (cross) to look at objects closer than the
> virtual 70 inches.

Yes, it would. The system would have to either track the eyes or rely on 
head movement to adjust the display to what the user is focusing on. It 
wouldn't necessarily need to physically move the displays, it could 
compensate for the display perspective in software. Ignoring this is 
obviously "good enough" for the brain, but it might slightly reduce 
strain.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: <chr### [at] tagpovrayorg>
http://tag.povray.org/

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