How do you generate a Vector Displacement Map without Mudbox or ZBrush?

polycounter lvl 14
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kodde polycounter lvl 14
Hey guys,

Sorry if this has been answered before. Tried searching the forums but had a hard time finding relevant info for my question.

I'm playing around with using vector displacement maps with ShaderFX in Maya and getting nice results with a few examples. Now I'm trying to figure out how to generate these maps myself without using Mudbox or ZBrush preferably. I've tried baking Directional Maps from xNormal. It gives me normalized(?) vector data in RGB and height data in the Alpha channel.

The VDMs that ShaderFX expects seems to only use RGB and by the looks of it has vector length in the RGB channels as well(?).  I've tried just multiplying the vector data by the height data and using that, but does not work correctly. It's resembling the results I want, but it gets skewed and not entirely correct.

Anyone have any ideas or knowledge to share? Thanks.

This is the type of VDM I want to be able to create.



Replies

  • kodde
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    kodde polycounter lvl 14
    Here's an example scene. The object on the left is the lowpoly plane with tesselation and the generated VDM applied. The object on the right is the high poly test shape. I generated the VDM with xNormal's Directional Map (Tangent Space and "Raw FP Values"), the Height Tonemapper dialogue I set it to so it wouldn't clamp and of the height range. This would give me a RGBA 32-bit exr with vector data in RGB and height in A. I then opened in photoshop, copied the data in the alpha channel to a new layer, placed this new layer below the vector data layer and changed the blending mode on the vector data layer to Multiply.


  • Shrike
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    Shrike greentooth
    Did you try filter forge ? The editor should allow such things
  • oglu
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    oglu polycounter
    if you are using them in maya i would go with mudbox.
  • kodde
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    kodde polycounter lvl 14
    Thanks guys,

    I'll have a look at Filter Forge as well. I was hoping to find a way where I didn't have to install a major sculpting suite for just the purpose of generating VDMs. Was hoping to learn a easier and alternate way of doing it if say I had both HP and LP in Maya. Think I'll install Mudbox either way just to see if I can get it right there either way.

    If anyone has any other suggestions or ideas I'd be grateful :)
  • shaderfx
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    shaderfx polycounter lvl 9
    I was once told that xnormal can generate VDMs.
    Never tried them in ShaderFX though.
  • kyrnal
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    kyrnal null
    I'm not sure if you included this step in your photoshop channel manipulation, have you tried adjusting the gamma of the heightmap channel before you multiply it into RGB?

    Anytime I've used VDMs in a compositor and there was a texture mismatch, the gamma is off.  Try 0.455 to bring it into linear colorspace, perhaps?
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