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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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    thrillhouse900
    Participant
    February 27, 2014
    Hey everyone, sorry I dissapeared a bit. I found 16 slots seemed to work good the stereo renders. But you shouldnt be getting black areas, that is strange. Try making sure your width is dividable by your slot number. (I should put a check in for that)

    I found 2048x2048 (2 2048x1024) to be pretty good on the DK1 Rift right now. 4k might be overkill.

    As for the errors, make sure you have 2 cameras named appropriately, and the dummy parenting them at the center. I think the dummy has to be named Dummy01.

    I will make a sample scene for you guys that are having troubles.

    George
    DK2: Processing. 9:51AM
    Nukemarine
    Up and Coming
    February 28, 2014
    "thrillhouse900" wrote:
    Hey everyone, sorry I dissapeared a bit. I found 16 slots seemed to work good the stereo renders. But you shouldnt be getting black areas, that is strange. Try making sure your width is dividable by your slot number. (I should put a check in for that)

    I found 2048x2048 (2 2048x1024) to be pretty good on the DK1 Rift right now. 4k might be overkill.

    As for the errors, make sure you have 2 cameras named appropriately, and the dummy parenting them at the center. I think the dummy has to be named Dummy01.

    I will make a sample scene for you guys that are having troubles.

    George


    Can't wait till this can be done with game engines. Probably be impossible for a let's play experience but more than doable for images at least till later systems improve.
    ghostlyfuAuthor
    Up and Coming
    March 6, 2014
    Hi All,
    thanks to tips from cheerioboy I'm making (some) progress making 360 stereo renders using Maya, Batch RenderRegion script and the Mental Ray LatLon lens. I'm working with 360x 5pixel-by-900pixel strips, rendered from a camera rig, turning (clockwise) over 360 frames. So far so good.

    The examples attached show my current issue: the warping that happens when the strips are sewn together (using StereoPhoto Maker) is just... weird. Also attached is a 'standard' (2D) equirectangular pano for comparison.

    E.g. notice the high 'billboard' which curves around you in the strip-rendered version but is actually a straight block, as in the mono render. Any thoughts most welcome...
    j1vvy
    Up and Coming
    March 6, 2014
    The curve of the billboard look correct to me.

    Are you thinking that the in the center where the left and right join that looks like one billboard in straighter?
    It is actually a little wider because of how the images are shifted then placed side by side.

    There is an annoying little vertical white line that is almost at the far left edge of the stereo view.
    cheerioboy
    Up and Coming
    March 6, 2014
    looks good ghostlyfu! I don't have the Oculus on hand to view these but it looks like you got it - try some tests with a checker texture on the objects to help check the stitching.

    I have a few architecture projects I hope to work more on to use in further stereo rendering tests
    ghostlyfuAuthor
    Up and Coming
    March 7, 2014
    Thanks both, the issue is better illustrated with checkers (another good tip cheerioboy). It almost looks like there wasn't quite enough visual information for a full 360, and what's there is being stretched over a 15 degree 'hole' (directly behind you in the Rift).

    Compare the standard (2D) pano to the 'striped & sewn' version attached and you'll see what I mean. This makes the billboard look curved.

    Not sure what part of my pipeline is at fault, camera is certainly rotating the full 360...
    j1vvy
    Up and Coming
    March 7, 2014
    Looks like you put together the stripes in backwards order.
    cheerioboy
    Up and Coming
    March 7, 2014
    Is your camera rotating clockwise? I haven't confirmed is this causes an issue, but I've always kept my camera rotations clockwise - that might also be why the strips might be in backwards order like j1vvy pointed out. I feel like I saw this early on but never understood why it was happening either... almost there!
    ghostlyfuAuthor
    Up and Coming
    March 7, 2014
    Thanks both,
    I'm not sure what you mean j1vvy, by 'backwards order' - it's a circle, right? Shouldn't that mean that the order of assembling the strip sequence is irrelevant? I'm Mosaic-ing with StereoPhoto Maker and there don't seem to be any options related to the order of assembly - can you explain this some more?

    One thing that could have been wrong is that each strip might be flipped horizontally (cheerioboy - I think that's the effect a counter-clockwise rotation has, see image attached). But they're not - my camera is rotating clockwise.

    I'm starting to wonder if the (virtual) nodal point of the camera has something to do with my problem? How did you guys determine where the common point of rotating both cameras should be?
    cheerioboy
    Up and Coming
    March 7, 2014
    I just use a dummy null object, link the cameras to that - and then drop in a geo plane and size that to the eye distance that I want. Use that as my guide in spacing the cameras.

    With your 360 spin, are you animating frame 0 - 360, having the camera match at both frame 0 & 360? Then you just leave one of those frames out of the rendering since they're the same.
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