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UE 4.19 - SpeedTree 8 adds noise to opacity mask and ignores a lot of channels

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  • UE 4.19 - SpeedTree 8 adds noise to opacity mask and ignores a lot of channels

    Hello,

    I am very excited for the new PBR workflow! However, testing out the beta I noticed a few problems:

    1. When exporting the tree the Alpha channel has some weird noise added to it and I haven't found any way to turn it off.
    2. There are texture channels for Specular, Metallic, Subsurface %, AO and Custom but when I export the tree the textures are nowhere to be found.

    Kind Regards

  • #2
    This is all by design. The textures are packed for optimal use in UE4.

    - The noise in the alpha channel will cause no problems, but it allows very fast blending on branch seams, detail layers, and billboard crossfades.
    - The default UE4 texture packing is Color/Opacity and Normal/Rougness. If you use subsurface, it is available in an additional texture (subsurface color * amount). Material AO is not used in UE4 for the most part, so part of it is baked into the color map.

    If you wish to change the packing or add additional maps, you can edit the UE4 texture packer in <apps install>/texture_packing/. There is an xml file that describes the channels and the .fx is the shader that fills them out. But note that if you change it too drastically, you will also need to adjust the UE4 importer code to handle the differences.

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    • #3
      Thank you for the fast answer!

      What you said is probably true for most projects, however we have a stylized approach and don't exactly use the channels as intended.

      I had a look at the xml and fx and it's actually adding the noise inside that and I could easily remove it. Having the exporter shader be open is perfect as it allows me to have Speed Tree export everything exactly as we need it!

      Kind Regards

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      • #4
        Yes, that is all new in v8. Glad you like it.

        We should have documentation on it as we come out of beta. You can see everything you have access to if you look at the STexturePackingInput struct in <install>/standard_shaders/TexturePacking_fs.fx.

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        • #5
          Originally posted by Greg Croft View Post
          - The noise in the alpha channel will cause no problems, but it allows very fast blending on branch seams, detail layers, and billboard crossfades.
          .
          The noise in the alpha channel WILL cause problems. If you use dithering opacity in ue4 - that will be be a hufe problem. Why there is no option to disable this?

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          • #6
            It still works with dithered opacity.

            But if you wish to disable it, just remove the noise from the UE4 texture packer shader, as mentioned above.

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