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  • Rendering Passes Gamma Problems

    Hi All,
    I have been trying to adapt using render passes to our current LWF setup.
    We don't use max's gamma and we use vray gamma corrections.. And "linear workflow" and "color mapping and gamma" options are always checked in our renders..
    Now,
    As we try to render simple test scene with render elements
    I use,
    Vray GI
    Vray Refraction (not needed for this scene)
    Vray Reflection
    Vray Lighting
    Vray Specular (not needed for this scene)
    And Blend them together in After Effects with additive mode.. When I compare the results with Vray RGB output the results are coming slightly different, but if the "Blend Colors Using 1.0 Gamma" option is checked in AE Project Settings then blended layers look the same with RGB output.
    PROBLEM: if I try to blend them together in Photoshop they look different than the RGB output and unfortunately there is no "Blend Colors Using 1.0 Gamma" in photoshop as far as know of (there is one but it does not work for blending modes)
    If we skip the LWF and render with gamma 1.0 from vray and save the render elements... things work fine both in AE and Photoshop (because Blend Colors Using 1.0 Gamma is not needed)

    To me looks like vray doesnt compensate the LWF for different render elements and later on Blending them at 1.0 gamma is required (rather than LWF's 2.2 gamma)

    What I have so far found out is, to render in different passes we have to either use gamma 1.0 or we have to use lwf + after effects, couldnt find a possible way of blending lwf with photoshop.

    I am posting a few images and the max file to explain better.
    Click image for larger version

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ID:	879843render passes issue to chaosforums.zip
    Cheers

  • #2
    In what file format and with what bit-depth are the outputted from Vray Render Passes?
    Svetlozar Draganov | Senior Manager 3D Support | contact us
    Chaos & Enscape & Cylindo are now one!

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    • #3
      I have tried rendering in 32bit exr and to separate jpgs, both gave the same result..

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      • #4
        I've just render your scene and compose it in Nuke and the result was the same as the Beauty Pass so everything in the scene and the Render Passes is fine.
        We do not have Photoshop in our environment so I am not able to help you on that matter.
        Svetlozar Draganov | Senior Manager 3D Support | contact us
        Chaos & Enscape & Cylindo are now one!

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        • #5
          we do also get good results on after effects (however if only the mentioned tickbox selected on lwf) however I am still puzzled on why the blending of layers would give different layers in lwf and gamma1 settings..

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          • #6
            The only way to get the passes to match in Photoshop is to blend them using 32 bit files. 16/8 bit files will not add up. Its an known limitation of 16/8/photoshop.

            Also make sure you are using ONLY Vray materials.
            CGI - Freelancer - Available for work

            www.dariuszmakowski.com - come and look

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            • #7
              Thanks for the feedback Dariusz,
              I had tested it with 32bit exrs result is just the same..
              I am uploading the psd file with all the layers.. to show the the difference between rgb and additive blended comp layers..
              s1.zip

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