On 03/06/2016 04:41 PM, Clodo wrote:
>> Would you please render, view and
>> let us know if the result OK or not?
>
>
> Your .pov in attachment, rendered with square 2048x2048 resolution:
> http://www.clodo.it/host/images/5f9811c6314aefa13bc7f619424fd0537f2b9483.png
>
> Rotate 90 CW with an external image:
> http://www.clodo.it/host/images/ec5b3235955cef0cbab6707b4a54259dcbd111dc.png
>
> and played in VR headset (spherical environment, stereo top/bottom) look almost
> ok in front view, but
> looking vertically up, there are issue:
> http://www.clodo.it/host/images/252fbce0fdc3188a7e1a2fedd7da7ba75e0471bc.jpg
> look the "leg" of the X, it's deformed and inverted between eyes.

Thanks for testing. First, am I correct that the top/bottom vs 
left/right in the stereo VR world refers to the placement of the left 
and right eye images and not to the intended orientation for head 
movement? Think the answer is yes, but want to be sure.

The pull apart up and down with the X doesn't surprise me. What I 
believe is happening is that at the top and bottom we are fulling seeing 
the pupil offset in the ODS approximation. This approximation is not 
noticed where things are all grey, but we see it clearly on the leg of 
the X while happens to be at the top pole.

It seems to me the ODS scheme will work reasonably well at the equator 
so to speak, and less well the further one or both eye tilt off it for 
single top/bottom images. It relates to what Alain said in another post 
to this thread in that to really do things cleanly you pretty much have 
to render another image/frame once one or both eyes much leave the 
existing image's horizontal/pupil equator.

That said. What I've got no clue about is what games might be getting 
played in the VR hardware itself & perhaps I missed some existing 
adjustment when reading the PDF? I can, for example, imagine a scheme 
which forfeits the 3D effect at top and bottom to prevent the visual 
pull apart.

Do you have other golden images where there is a thin shape like the leg 
of the X cross at or very near straight up or down? Might clue us in to 
what special handling gets done at the poles - if any.

>
> Sorry but it's difficult to understand if the 3D effect is correct in your
> example, and i'm fail to render other scenes.
> I took the "spherical.pov" sample from Povray distribution.
> standard camera{spherical} render (2048x2048):
> http://www.clodo.it/host/images/4ecb53b74a7ffdb39369f14fd2664aeb7c6aa817.png
> Simply comment the camera, adding your code (final .pov on pastebin:
> http://pastebin.com/ajyHzH1E )
> render:
> http://www.clodo.it/host/images/69f31e143d340ce078a07a349108b0466271b868.png
>
> Also my scene with your mesh camera render totally unexpected big pixels:
> http://www.clodo.it/host/images/160d46699c5da84daa11d06362b36856173497a7.jpg
>
>
> All tests rendered with version 3.7.0.msvc10.win64, the official stable.

The spherical.pov is set up with the camera location at a y of 10 where 
the mesh camera as defined is at the origin. Something I should have 
added as a note in the header is that the usual available camera {} 
transformations do not work with the mesh camera. You can move the mesh 
camera to the same location at the spherical camera in spherical.pov by 
changing the line :

  mesh { Mesh00 rotate x*(360*(i/ImageHeight))}

to

  mesh { Mesh00 rotate x*(360*(i/ImageHeight)) translate <0,10,0> }

This will eliminate the big pixels - at 0,0 the camera is sometimes at 
or in the scene's plane.

This leaves us with the fact spherical.pov is set up as shapes on the 
X,Z plane Y up which doesn't match the ODSC mesh cameras fixed X+ up so 
the result will be oriented differently than the spherical camera result.

>
> --------------------------------
> In the mean-time, i compiled the patch of Paul Bourke
> http://paulbourke.net/stereographics/povcameras/
> with old PovRay 3.6.1 sources, with my scene with floating spheres,
> settings zero-parallax far away (1000), IPD 0.065 and test in with VR headset.
> For me, it's perfect, projection, scale and 3D effect.
>
> I still have issue to porting it to POV-Ray 3.7, i don't know how to convert
> VLinComb3, Ray->Initial etc.
>
> --------------------------------
> The new function-based user-defined camera available in 3.7.1 alpha look
> interesting, but i'm totally newbie about using it to render a spherical stereo.
>

Yes, cool feature for sure & not just for stereo implementations. I too 
would need to think for a bit on how to code up the ODS camera with it.

Bill P.

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