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VanKurt
Participant
July 29, 2014

Problems with (stereo) 360° CGI renderings

Hi,
I'm taking my first steps with creating stereo panoramas using 3ds max and Vray. As suggested in another thread, I have two cameras rotating and rendering small image slices. The slices are then stitched to get a left and a right image.

So far things work quite well, but my images are never flawless. They appear somewhat "strippy" and contain small artifacts. I believe that both problems may actually have the same cause. But I can't figure out what it is :(
I've attached an example image that shows the problems:
Left.jpg
Maybe the problem is somewhere in my scene or camera setup? This is what I use:

Camera setup:
- Two cameras with parallel orientation
- Interocular distance: 70mm
- Pivot of camera rig centered between the two cameras
- Camera type: spherical panorama

Camera rig animation:
- Clockwise rotation
- 360 frames rendered (0 to 359)
- Start angle: 0° on frame 0
- End angle: -359° on frame 359

Slice dimensions:
- Horizontal: 1°, 10px
- Vertical: 180°, 1800px

Single image (left resp. right) dimensions:
- Horizontal: 360 Slices, 3600px
- Vertical: 1 Slice, 1800px
- Aspect ratio: 2 to 1
- Slices are stitched with custom tool (simply aligns slices one after another)

Final image:
- Left image on top, right image below
- Size 2048x2048 px (scaled down from original 3600x3600 px)

    5 replies

    j1vvy
    Up and Coming
    July 30, 2014
    I am just looking at the flat image, not interactively, but I think it is just parallax of putting together images of the moving camera.

    Try:

    Slice dimensions:
    - Horizontal: 0.1°, 1px
    - Vertical: 180°, 1800px

    Single image (left resp. right) dimensions:
    - Horizontal: 3600 Slices, 3600px
    - Vertical: 1 Slice, 1800px
    VanKurtAuthor
    Participant
    July 30, 2014
    Horizontal: 3600 Slices, 3600px

    Good idea. I'll try that. Hopefully the rendering time will still be manageable ;)
    I'll post the results as soon as possible.

    Do you think some sort of post-processing on the slices could help?
    At the moment I'm just stitching them one after another with a little tool I wrote. So maybe creating some sort of smooth transition between every two slices could also help?
    VanKurtAuthor
    Participant
    July 30, 2014
    Bad news! I tried the settings you suggested, and rendered 1px stripes.
    The result is even worse (see attached image).
    Also the rendering tme went up to >24h (on an octa core machine). Yikes!

    So I guess it must be something else. Any suggestions on how to fix this are welcome :)

    BTW: If anyone is interested in my stitching tool, you can download it here http://www.fun4mobile.de/shared/Slitcher.zip.
    It can stitch slices (thus it's called "Slitcher") and create anaglyph or over/under images from them. Any feedback is welcome :-)
    j1vvy
    Up and Coming
    July 30, 2014
    I don't do ray tracing. I mimic what you are going with real cameras.
    I specs for the camera must of off in some way. But not sure how.
    If you render both a 2° strip that is 20 pixels wide and a 1° strip that is 10 pixels wide and place them on top of each other and do a difference in Photoshop. The overlap should be identical.

    You may be able to hide this by rendering 1° strips but incrementing 0.5° to end up with 720 strips each of 10 pixels then blend those strips together.
    bcoyle
    Up and Coming
    August 8, 2014
    I could be wrong. But I think the striping is from the render settings. You're using Vray, no?
    I'd try two things:

    Precalc both Irr/LC, and see if the striping goes away
    -or-
    if using BF/LC, turn up the LC settings.. or bake LC and run BF/LC.

    I think there's something that causes slight GI differences between each strip. Hence the banding.
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