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  • Exposed area of Rectangle/Disc lights

    When 'invisible' is unchecked on disc and plane lights, their visible area is insanely bright (currently in this scene the float on them is ~40 where other over-exposed areas in the shot are ~2.0). The edges get really aliased and their reflections are way too much. I always end up making them invisible and using a vraylightmtl on geometry to fake it.

    I did notice when you put the light multiplier to 1.0, the visible area is more under control (float=~3.0). But I regularly crank these lights up to 10-20.0 for the camera exposure settings to make sense in the shot.

    Is there some way to control this? Or am I completely lighting things wrong and it shouldn't be an issue?

    Another problem I ran into is when you add a 'directional' value under the Rectangle/disc light rollout, it will gradate the exposed light (but also knocking it down to a more tame value) [see attached]

    Click image for larger version

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    Click image for larger version

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    Thanks in advance!

  • #2
    This is how antialiasing filters deal with floating point values. You can overcome this by using the "clamp output" feature, but this will limit your dynamic range in the viewport to a maximum value of 1 (255,255,255).

    What happens is the AA filter looks at samples with a large amount of contrast between them and tries to take an average; the problem with this is that a average between 40 and 0.5 is still ~20, so it will return very bright (>1) pixel value. If clamp output is enabled with 1 as your maximum value, the antialising filter will be able to take an average between 1 and 0.5, yielding 0.75.
    Check out my (rarely updated) blog @ http://macviz.blogspot.co.uk/

    www.robertslimbrick.com

    Cache nothing. Brute force everything.

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    • #3
      Thanks for the reply. Is there any way to turn down the intensity of the exposed disc without affecting the light output? That would be really nice. Clamping isn't an option

      Do you know what the deal is with the directional value gradating the exposed discs?
      Click image for larger version

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      • #4
        Originally posted by atrask@hksinc.com View Post
        Thanks for the reply. Is there any way to turn down the intensity of the exposed disc without affecting the light output? That would be really nice. Clamping isn't an option

        Do you know what the deal is with the directional value gradating the exposed discs?
        [ATTACH=CONFIG]28011[/ATTACH]

        still waiting... :P
        http://forums.chaosgroup.com/showthr...ht=directional

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        • #5
          Use luminous geometry rather than the lights themselves. Set these objects to not cast shadow or affect GI or reflections.

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          • #6
            lol... So if it's been 2.5 years is it safe to say this will never happen?

            Use luminous geometry rather than the lights themselves. Set these objects to not cast shadow or affect GI or reflections.
            Currently do that, but it'd be much quicker and more intuitive to have that control native with the light.

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            • #7
              Originally posted by atrask@hksinc.com View Post
              lol... So if it's been 2.5 years is it safe to say this will never happen?
              Nope, some things just need more time because of other more important ones.
              Svetlozar Draganov | Senior Manager 3D Support | contact us
              Chaos & Enscape & Cylindo are now one!

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