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vray carpaint shader driving me crazy

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  • vray carpaint shader driving me crazy

    Hello community,

    I am working on a car viz project and I am experimenting with the vray car paint shader and I am not able to adjust this shader so that it works. My problem is somehow the scaling of the flakes. When I use the default settings of the shader, it comes with the "explicit mapping channel" option. No clue what the channels do or where to look, but I assume it takes in account what my actual uv´s of the car look like.
    Mine are within texture space (the square where everything should be in) mapped, since I have some decals on the car.
    Anyway, If I use this setting, I am actually out of range of the flake density, scale or size settings and I can´t get a convincing look.
    When I change the mapping to "triplanar in object space", I assume, it projects the flakes from 3 sides in the size of the object onto the surface of it. My settings now seem to be in range, but I get crazy blurry regions. But only on the flakes, my textures look fine. Now, when I create a sphere and apply the same shader on it, it renders in different size (flakes are smaller). The size of the sphere was about the hight of the car.
    When I distort the sphere to fit the length and width, I would assume, that the bounding box of the triplanar projection would be somewhat of the car and the flakes would be the same size as the car.......wrong! The flakes dont change the size. I am kind of clueless what the issue here is. I would be so thankful, if someone could get me this thing solved.

    Very much thanks in advance.

    Click image for larger version

Name:	Bildschirmfoto 2014-05-02 um 15.24.32.jpg
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ID:	879837Click image for larger version

Name:	Bildschirmfoto 2014-05-02 um 15.24.32.jpg
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Size:	262.5 KB
ID:	879837

    As you can see, there is no distortion on the sphere. But the car looks crazy.

  • #2
    It would be best to post a simple scene with just a part of the car either here or you can send it to me at vlado@chaosgroup.com so that I can look at what's going on.

    Is your car scaled in any way?

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

    Comment


    • #3
      Hey Vlado, thanks for the reply. I did send you the file. The scene units are set to cm and the car is in its original size (4,8m length). But I tried it also with changing scene units to meter or scaling the car down, so that it fits back in the default size of the grid in cm. No good results at all. The mesh has a uv mapping for my decals and first I thought this is somehow related to normals but when I used my textures on it, they came out fine.
      Hope this helps in figureing out whats going on here.

      Thanks

      Comment


      • #4
        Alright, got it fixed with the help from Vlado.

        So the issue seems to be if the geometry is modeled on default grid canvas size. The meshscale is usually 1 1 1 for x y z. Since the car has a lot of different groups they are all packed into one big master group and that one has been scaled to fit real world size of the car. That seemed to cause this problem. It did not fix the problem to scale the group back to 111 and only scale the car chassis or the single bits. I first thought this is a bug within the group node.
        Well at the end, only freezing the transformation on the master group node fixes this issue. Crazy that in my screenshot here the distortion did not show any unregularities. Anyway big hugs and thanks to Vlado for taking time in looking into this.

        have a great day (its sunny here )

        Comment


        • #5
          Ah, very cool Let me know if there is anything else. We will still try to fix the rendering even in the original scene though.

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

          Comment


          • #6
            Yeah...helped me a lot. Ive got some spots on the door now, but I think that comes from interpolation, since I started creating a two-flake car paint shader with vraymtl and blendmtl. And maybe the vraymtl is causing some issues here. Anyway a quick shot to show its going well.
            Again , thank you Vlado,

            Click image for larger version

Name:	challenger_carPaint.JPG
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ID:	851944

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