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ghostlyfu
Up and Coming
October 9, 2013

360x180 CG Renders

I'm facing a problem when rendering any pair of equirectangular images from inside a 3D modelling package (Maya in my case, but no doubt the same issues apply to many different packages). The attached (side-by-side format) image is an example. I'm hoping the good folk on this forum can help.

I render out my panorama (I use the Lat-Lon Mental Ray lens plug-in) and it looks as you'd expect. Looking at it through the excellent VRPlayer, it works well. I then shift my camera to another position approx 6.5 'virtual' cm to the side of the first position and re-render. Again this panorama works fine on its own.

I was hoping that I could just place these x2 renders side-by-side (as they are in the attached example) to make a 3D version of the scene. Not so. What's happening is that the 'forward' view works fine but the depth gets reversed towards the peripheries of the image (which just looks bad) until the 'back' view is completely inverse (and so look pretty much OK again).

Logically I can see that the reason is that the 'Right camera' becomes the 'Left camera' as it renders the part of the view directly behind itself. However, I haven't got a clue how to fix it and output an equirectangular panorama that works in 3D. Help!

    165 replies

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    WerTicus
    Participant
    September 8, 2014
    Thanks Kim

    I've directed the creator of vray to this thread and he has taken notice and it sounds like they might be working on a solution for vray users.

    http://forums.chaosgroup.com/showthread.php?70014-Vray-Stereo-camera-Spherical&p=630488#post630488
    Philipp
    New Participant
    September 11, 2014
    I'm working at FaberCourtial in Germany, a vfx company where we've been creating a major project for the Oculus Rift.
    We developed a Stereoscopic Panorama Camera Shader for Vray that has been giving us some good results and we could share some examples of our work if you're interested.
    WerTicus
    Participant
    September 15, 2014
    Yes Im pretty sure we would love to see your examples :)
    Philipp
    New Participant
    September 17, 2014
    Here is a preview rendering from one of our projects. You can watch it in VR Player with the attached settings file, although in our own player it works even better. Everything is rendered with VRay in one go, no stripes and stitches were needed.
    mediavr
    Up and Coming
    September 17, 2014
    It looks great and extremely natural but there is not much depth visible in the distant buildings. Maybe that is because you are rendering with a standard interaxial distance (6.5cm) but a hyperstereo rendering would make the buildings look fantastic in 3d. Yes then the birds would be too close to converge ... re stripes .. arent "stripes" slightly visible in the centre of the bottom of the frames -- where equirectangular mapping has made them more visible in that mapping?
    Philipp
    New Participant
    September 18, 2014
    The distortion is an effect that happens especially to objects close to the camera. We are currently optimizing the shader to minimize this effect. I uploaded an updated preview rendering where the bottom point is at a larger distance, so the distortion is less recognizable.
    pixelmind
    Participant
    September 18, 2014
    Looking good. In my experience it's the best compromise to fade out the stereo offset towards the poles to minimize the distortion and stereoscopic problems when objects are directly on top or beneath the camera. It will result in a mono image at the zenith and nadir but most of the time the transition is barely noticeable.
    j1vvy
    Up and Coming
    September 18, 2014
    Faber Courtial looks realy good.

    I wish there was a way to combine stereoscopic and depthmap to get some 6DoF.

    Can VRPlayer or another viewer show SxS or O/U combined with depthmap?

    I would like to compare O/U, depthmap, and O/U with depthmap. Can someone please render the same image as both.
    I want to see the zenith.

    I have mentioned this before in another thread

    The thing I don't like about depthmap is how the recreating stereo pairs that have objects in the foreground, a little bit of the background needs to be computer generated. Why not warp or compress the background a bit when creating the image? Then expand the background when viewing the image?

    I see this being quite easy to implement with CG ray-traced graphics. Imagining the depth map having a gravitational pull when tracing the rays to create the image and doing the reverse when viewing it.

    Harder to create from multiple images, but should be doable after the depthmap is created. Unless someone already invented this maybe call it a warp map. Also need a comparable viewer.
    pixelmind
    Participant
    September 18, 2014
    The sponza scene was the only one I had laying around right now. Nothing interesting to see at the zenith but maybe it's still usefull for testing.

    IIRC the VR-Player depthmap option only works with one image + depthmap . I havn't tried it yet though.
    A point position pass would propably give better results ( http://vimeo.com/11074371 ) . If I find some time I could try to write a viewer/player which displays the pixels as points in 3-dimesional space when you supply depth/position infomation.

    Not sure about your warping idea but maybe you could render the scene from different viewpoints and merge the images into a single point cloud to fill some of the occluded areas.
    j1vvy
    Up and Coming
    September 19, 2014
    Thanks. The stereo vision is many times better than the depthmap version. Using VRPlayer there are a few errors in the depthmap version that I can not account for looking at the dephtmap. I suspect some error in the viewer.

    I still like my warping idea. It wont compete with creating textures of the 3D space for covering the entire space but it should be less data to transmit.
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