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Clamped Colors (what are them?) and reflections problems...

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  • A Offline
    AcesHigh
    last edited by 16 May 2011, 11:39

    Hi... I just tried rendering a scene that rendered well on my previous computer (a Q9300) on my new computer (i7 2600).

    the scene rendered well and fast, but I noticed some problems on the reflections. Basically, some black, aliased (as not anti-aliased) reflections.

    After some tinkering, I noticed that adjusting the Exposure of the scene could increase or decrease the problem... at -0.27 exposure, the bad reflections disappeared completely.

    Then I turned on Clamped Colors (which I have no idea what they are) and I noticed that at -0.27 there were no clamped colors... the entire screen was gray... but when I increase the exposure (at -0.27 its TOO dark), the SAME AREAS where the bad reflections appear, also appear when I turn the Clamped Colors layer/mask of the render window.

    What the hell is going on after all??

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    • L Offline
      ledisnomad
      last edited by 16 May 2011, 15:27

      I'll try to explain clamping to get things started. Maybe others will chime in. Although since it rendered OK before, I don't know why it wouldn't be OK now.

      In any image, there is a range of colors from black to white. Let's say the colors go from 0 to 255, right? Well, your camera may only be able to handle a range of 240 colors, so you could set the exposure to see 0-239 or 15-255. In the latter case, if there are areas of subtle shadows, you'd lose detail because the camera can't see it. In the former case, if there are bright areas of white or almost white, all that will get washed out.

      In your case, this is what is happening. If you have the colors clamped, anything from 240-255 is shown as white. If you unclamp the colors, the Vray frame buffer represents 240-255 with solid colors from yellows to reds to black.

      If you don't want any part of your image burned, then you need to adjust your exposure like you did until there is no difference between toggling the color clamping on/off. I'm not quite sure what you mean by:

      @unknownuser said:

      ...but when I increase the exposure (at -0.27 its TOO dark), the SAME AREAS where the bad reflections appear, also appear when I turn the Clamped Colors layer/mask of the render window.
      Can you post some images?

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