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  • VrayScatterVolume brightness

    Hello,

    so I am now tasked with creating realistic closeup snow. SSS in VrayMTL seems to work well for this, but unfortunately rendertimes with are are extreme, so it's not really usable as long as I want to be able to render out my animation. Both FastSSS2 as well as AlSurface do not work as they are based off a solid SSS models, which make it impossible to get transparency towards the edges of snow intersecting with something, making the snow always look like wax rather than frozen water.

    So ScatterVolume would be ideal for this, it is fast and is based on transparent SSS model. The issue here is that I just can not get white volume out of it. Even if I crank up scatter color to 255, bounces to 20, it just looks as if it was clamped somewhere around RGB 160. The best I can do is get somewhat bright gray color. Is there anything I can do to make scatter volume white? For example Corona's VolumeMTL does not suffer from this issue. If I make very dense volume sphere with scatter color of RGB 210, and put it next to a sphere with diffuse material that has same diffuse value, they more or less match. Where as in V-Ray, if I do the same, it looks like a coal brick next to snow.

  • #2
    Will see what's going on, but in the meantime you should be able to use a fastsss2 material with single scattering set to "raytraced".

    Best regards,
    Vlado
    I only act like I know everything, Rogers.

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    • #3
      Thanks! Unfortunately FastSSS2 does not work either. Both raytraced and raytraced (refractive) modes use solid SSS model, so there is visible sharp transition on the edges of the snow:
      Click image for larger version

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      BTW they appear to have same brightness because FastSSS one has scatter color at RGB 128 where as ScatterVolume has scatter color set at full 255.

      I've actually found out how to make ScatterVolume bright enough - by setting BlendMTL which blends ScatterVolume with refractive VrayMTL to be in Additive mode, But unfortunately, rendertimes more than double

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      • #4
        Yeah, it looks like the scatter volume material is darker than it should be. I'm looking into it now and if there is a bug, I should be able to get you a build probably tomorrow.

        Best regards,
        Vlado
        I only act like I know everything, Rogers.

        Comment


        • #5
          Awesome! :]

          Comment


          • #6
            Sent you an email. Still not quite where I want it in terms of sampling, but it should be better.

            Best regards,
            Vlado
            I only act like I know everything, Rogers.

            Comment


            • #7
              Hi, I have the exact same problem. Trying to make sugar. My sugar is grey. Is your modif in the nightly (I use 3.50.04).

              I thought I could use the light multiplier that is mentioned in the doc but that setting is nowhere to be found.


              @recon442 By the way if the additive mode makes the render too long maybe it's just because you have some overbright pixels, so it may be just a matter of rebalancing the speculars in all your layers. I thougth of using it too but didn't try it yet.
              Last edited by jstrob; 11-04-2017, 05:36 AM.

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              • #8
                Originally posted by jstrob View Post
                Is your modif in the nightly (I use 3.50.04).
                It's in the 3.57 nightly builds, yes.

                Best regards,
                Vlado
                I only act like I know everything, Rogers.

                Comment

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