Harold,

> Great precision in stereo base calculation is not necessary.

You must have much more experience in this field accoring to your postings.
The human eyes and brain can compensate large keystone distortions in some
cases. In other cases a small distortion causes the eyes not to converge.
What is the important difference between the situations?

> Stereo photographers rarely need to resort to complex
> equations, the 1:30 rule is more than enough unless extreme
> lens focal lenghths are involved.

But the resulting images are adjusted when mounted. In raytracing, my goal
is to do this adjustment by setting the camera properly.

> By "vector between the two eyes" do you mean convergence?

Unfortunately (due to my poor English), I don't know the English counterpart
of all the ususal expressions in this field. For example: I've learned the
"keystone distortion" expression from this thread. Can I learn convergence
too? ;-))

"vector between the two eyes":

#declare rv=<0.0325,0,0>    // position vector of the right eye
#declare lv=<-0.0325,0,0>    // position vector of the left eye
#declare ev=rv-lv                    //vector between the two eyes

> Again, parallel cameras is your best solution, but if you do
> "toe in" or converge the cameras then you do need to be
> precise.

This can be the difference between the situations mentioned above. :-)

You're right. Parallel cameras are the best solution, but post-rendering
adjustment of images are needed to view with red-green glasses or shutter
glasses, where the images should go to the same surface (not cross-eyed
view).

> You will also need to limit the depth of field because
> what is sometimes called "on screen deviation" (the displacement
> of left and right images on the screen) may cause the eyes to
> diverge (rotate out) which is very uncomfortable!

StereoTestA.pov renders a "star field" pattern to the skyglobe at infinite
distance. It causes the human eyes to converge at infinity, so the eyes goes
parallel. Divergence is really unconfortable. I couldn't cause my eyes to
diverge, because stereo_base measured in display metric did not exceed
6.55cm. Conclusion: Physical dimensions of display is important when
displaying stereo images, because stereo_base can easily go above 6.55cm in
real world (monitor) metrics.

> I've never created an difficult to view stereo pair result from
> using the 1:30 rule and parallel cameras.

Are your final prictures (on paper or something else) much smaller than the
visible area of a 17" computer monitor?

Thanks for your help, Vic

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