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Vray3 vraydirt darkness and alpha with matte objects/materials

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  • Vray3 vraydirt darkness and alpha with matte objects/materials

    Is there any way to adjust the darkness of the Vray dirt in Vray3? In older versions piping it into an output would make it darker but I can't see to get that working in Vray 3. Am I just doing something wrong? I've tried both putting the vray dirt in the output and putting an output in occluded color for the dirt. Is this part of what's happening with the reflection mattes as well? If so, I get it and it's cool. If not, where am I going wrong?

    Also, I think I used to be able to get vraydirt to affect alphas on matte objects but I can't seem to do that on Vray3. I have a situation where I'm lighting a scene with just the environment color and using an HDRI for reflections. Because of the nature of the project it doesn't use actual lights. Dome light didn't solve the problem though I thought it might, so I don't think I really understand the real problem.

    The real problem is that my matte shadows around the feet of the character are very light because of my weird setup, and I need to find a decent way to darken them up without having to paint in post due to the sheer volume of images. The problem I'm sure is that they aren't casted shadows but more like GI shadows, which I think is causing the pain.

    What I tried (and failed) to do was put the ground material in a wrapper, set the matte up (-1, affect shadows, affect alpha, matte object) and then try to use a vray dirt in the diffuse to help boost the ground contrast near the objects/characters against the white background a bit as they are too light. I'd hoped that the AO would be added to the alpha of the ground matte, but so far I can't seem to make it happen. I may have tunnel vision after spending too many hours trying to get it to jive. I've also tried the AO in the GI settings but it seems to ignore matte objects.

    I'd think there would be an easy way to do this but for the life of me I can't seem to nail it down. I attached a screen for reference. In the end I just want darker AO and more of it to affect my alpha. I love what's going on there, I just need more of it.

    Click image for larger version

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    Thanks for any help. Any ideas would be greatly appreciated.

    EDIT: I did figure out how to increase the darkness of the Vray Dirt effect by using a VrayCompTex and multiplying 2 dirts together. Worse case scenario I can get by with just this Comptex AO if I could get it to affect the alpha of the matte somehow. Sadly it's going into photoshop so I don't have a node based alpha network in post. Maybe some sort of operations on an ao and the matte?
    Last edited by Deflaminis; 27-06-2014, 02:10 AM.

  • #2
    Maybe there is a command to boost the GI amount past the limit of 1? I know it's not physically accurate, but is that a possibility? I just need to boost those alpha levels (evenly) anyway I can. I did try to screen an inverted AO by the alpha but no luck...

    Maybe somehow use distancetex?

    EDIT: In the end I just split the GI and Reflection HDRI's and rotated the GI HDRI until it was darker in front of the guy. Still interested if there's a way to get the vraydirt or ao into the matte alpha.
    Last edited by Deflaminis; 27-06-2014, 06:58 PM.

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    • #3
      Originally posted by Deflaminis View Post
      Is there any way to adjust the darkness of the Vray dirt in Vray3? In older versions piping it into an output would make it darker but I can't see to get that working in Vray 3.
      This works fine even in version 3.0 - just plug the VrayDirt map into OutputMap, activate Enable Color Map option and change the Color Map curve to get the effect you are looking for.

      Originally posted by Deflaminis View Post
      Maybe there is a command to boost the GI amount past the limit of 1? I know it's not physically accurate, but is that a possibility?
      There are several ways to boost the GI:
      1.From Main GI settings:
      Click image for larger version

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      2.From Matte Options:
      Click image for larger version

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      3.From Vray Object Properties:
      Click image for larger version

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      4.By using brighter material into GI-override material:
      Click image for larger version

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      Feel free to send us a part of that scene for investigation if you still have difficulties to set it up.
      Svetlozar Draganov | Senior Manager 3D Support | contact us
      Chaos & Enscape & Cylindo are now one!

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      • #4
        I'll give it a go. Thank you.

        EDIT: Can't get them to go past 1 on many of these. I'm looking to boost the alpha values of the matte, not the overall GI solution. Make sense?

        Any ideas for getting AO (Vraydirt) as part of the matte opacity?
        Last edited by Deflaminis; 30-06-2014, 10:46 AM.

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        • #5
          I am sorry, I didn't realize that you are talking about the alpha-shadows generated from GI.
          Unfortunately it is not possible to increase the GI-matte-alpha-brightness from Vray - it is possible only to decrease it via GI amount.
          In any case the alpha-channel is used during the compositing stage, wouldn't be possible to increase its brightness in post via curves-tool for example?
          Another option is to values between 0 and 1 for Alpha Contribution value for matte object - it will produce brighter alpha but I don't know if it is going to be useful afterwards.
          Svetlozar Draganov | Senior Manager 3D Support | contact us
          Chaos & Enscape & Cylindo are now one!

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          • #6
            Understood. As soon as I added a light, everything working itself out. I was going for a setup that I guess had some theoretical issues long before technical ones. The render times even got way faster afterwards so it was an easy sell. Everything is working fine now and I thank you for your time.

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            • #7
              Thanks for the update.
              Svetlozar Draganov | Senior Manager 3D Support | contact us
              Chaos & Enscape & Cylindo are now one!

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