Am 24.10.2014 22:16, schrieb Stephen:
> On 24/10/2014 20:37, Le_Forgeron wrote:
>> I have a patch for a stereoscopic camera in povray.
>>
> Interesting?
>
>> You have to consider a few things:
>> * what is the distance between the centre of each "eye" ?
>
> Indeed! and what effect does increasing the distance have?* Some of my
> reading suggests that for distance shots an extended baseline is
> recommended.

I consider that recommendation nonsense: Yes, long-distance shots with 
standard eye distance are problematic for 3D because they provide little 
to no 3D effect at all.

However, increasing the eye distance has exactly one primary effect: It 
makes the scene appear smaller. (Likewise, decreasing the eye distance 
makes it appear larger.)


>> * where is the focus point where both centres of picture's rays meet.
>
> Again, is there a recognised behaviour when you change that point?*

My recommendation would be to put the focal point at a distance 
equivalent to the expected viewing distance to the screen.

Changing that point won't mean a thing to the 3D effect, but may cause 
discomfort.


There's one other very important thing to consider though: Camera angle. 
For best results, the camera angle should be the same as the expected 
"screen angle" in real life. Any other than that, and you'll introduce 
distortions that may cause discomfort.


All in all, the camera parameters should match the expected viewing 
situation as closely as possible, with the display corresponding to the 
look_at plane.


Obviously, following this advice is not practical, because it severely 
limits your choice of camera perspective :-P - but it should give you a 
sound starting point.


>> * do you want parallel or crossed visualisation
>
> I don't know. I have lcd shutter glasses I guess that parallel would be
> more comfortable.

With LCD shutter glasses, the question is irrelevant, as it applies only 
to side-by-side viewing.


> The articles I've read talk about a lens's near and far points depending
> on the focal length of the lens. Which in itself gives an estimate for
> the angle of view.
> That is not pinhole camera stuff. (I hope)

Stick to the pinhole stuff, it is actually a better fit to the viewing 
situation (presuming you don't have one of those fancy new curved panels).

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