Hi!

> I don't know which of us is confused, well
> I know I'm confused... I hope I'm not just
> telling you things you have already considered,
> anyway...

Sorry about the new tree with the same problem, I accidentally pressed "New
post" instead of "Reply group".

> when you change the look_at  or location without an
> equal change in the other you effectively
> rotate the camera, which is different from what
> you describe as changing the "screen position"
> or shifting the image plane.

I see. It was not logical to me, but I've been lightened some of the
postings.

> The problem you are noticing could be
> "keystoneing" which is the geometric distortion
> created by rotating the camera.

Yes. It is.

> I think what you want to do is set the
> "stereo window".  By adjusting the
> location of the boundaries of the image
> you can place the z dimension relative
> to the viewing plane. In stereoscopic
> photography this is usually done when the
> images are mounted.

I rendered the left and right images independently, then adjusted the views
in my new viewer. But it was not precise, because this method has only one
pixel precision. This is not a big problem, but not correct anyway.

> Whenever I make stereo pairs I keep the
> cameras parallel by shifting both the location
> x dimension and the look_at x by the same
> amount. Then there is no distortion. I set the
> stereo window by trimming the edges of the
> finished image.

This method is used in my viewer also.


> patch to POV-Ray called Stereo POV 0.1.
> It will create stereo pairs and set the stereo
> window so you don't need to trim the
> images after they are rendered.
> Try his patch and let us know what you think.
> http://www.geocities.com/stereopov/

I've downloaded his entire page and read some details. It seems to be good
for my purposes, but supports only Pov 3.1g. I use Pov 3.5 with the improved
Windows GUI and don't want to fall back to Pov 3.1g. I've used Pov 3.1 a lot
2 years ago. I plan to put some of my scenes to a WEB page. I hope Hermann
will port his (at first look) excellent patch to 3.5 in the near future...

As far as I can see I have to write a simple include file with the matrix
transformation proposed by Alex & Slime in a recent posting. There will be
some problems with animation, so I will have to calculate my own "clock"
variable from frame_number. It is also possible to render left and right
animation independently. It's because I have to finish my thesis in three
weeks and I've no time to wait for a new patch. Sorry.

> Unfortunately
> I find his patch troublesome because it is
> based on a specific "metric" and confuses
> me because I have to design scenes based on
> real world proportions, ie camera at 2m and
> a stereo separation of 0.065m. I find it difficult
> to adjust my existing scenes to fit this metric.

The metric is offten confusing to me, but your problem is not clear to me.
In Stereo Pov these properties can be changed by setting stereo_base and the
right and up vectors according to it's documentation. What are the
difficulties with your scenes?

- Vic -

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