"Chris Huff" <chr### [at] maccom> wrote in message
news:chrishuff-B43B9F.10013925022001@news.povray.org...
> In article <3a96ebbf@news.povray.org>, "yooper" <Out### [at] huntelnet>
> wrote:
>
> >  shoot for 1 unit of displacement for
> > every 30 units of distance to the target.  If your camera is 30 from
> > the wall, shift the camera 1 unit to the right.
>
> Where does this "rule of thumb" come from? Your eyes don't get farther
> apart when looking at distant objects, they stay the same distance apart
> and rotate to be closer to parallel. And the distance of the separation
> should be fairly close to what it would be if you were standing in the
> scene, or the scale won't look right.

I had read somewhere that 1 unit separation for a focal point 300 units away
was a good idea for the average scene.  Of course the best way would have to
be to use units as a real world measurement, say inches, and go from there.
Obviously still needs to consider field of view (angle or direction in
camera).
I agree with Chris here that following actual human eye characteristics must
be the way to go, however maybe the reasoning not to do so has to do with 3D
photography in some way.  I guess most any camera was/is setup to look
parallel because of perspective changes from the parallax eyes usually have
would cause some kind of non-alignment trouble.
It's not something I've truly learned anything about so I'm just chattering
mindlessly here.
The stereo pairs I posted just now here at p.b.i. have more than a 5 unit
shift with focal point some 600 units away, the camera being rotated around
that.  Scale based on that would make the scene just room-sized and not the
large open spaces it is supposed to be.  25 feet (7.6 meters) to the middle
of the image.

Bob H.

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