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Eden Exposito avatar image
Eden Exposito asked ·

C4DtoA displacement seam problem - Standard Surface Anisotropy tangent related

Hello,

I'm having issues with displacement map and UV seams. As you can see in this screenshot when I use an Arnold Material with texture added in displacement I can see UV seams throught Arnold Render, but If I put the same texture desplacement file in a C4D native material and see result throught Arnold Render I see no seams cuts (I know, obviously use C4D native material to render Displacement in Arnold is wrong).

In this link https://www.dropbox.com/s/kiuscxdidlihag7/Displacement%20Test.zip?dl=0 you can download c4d file and texture to test it. Inside it you can see two materials (c4d material and arnold material with displacement) try to apply one and other and see it throught arnold ipr.

What is happening? A bug? I'm using wrong displacement?

Thanks!

c4dtoadisplacementstandard surface
displacement.png (828.9 KiB)
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Peter Horvath avatar image
Peter Horvath answered ·

Seems like the displacement is breaking the tangent space of the mesh and you have to feed the anisotropy effect with the proper tangents as you have found out. So actually the renderer is doing the right thing.

About the pole (where you have the circular reflection), this is expected on closed meshes. A workaround could be to use a map for anisotropy and paint it to 0 near the pole.

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Eden Exposito avatar image
Eden Exposito answered ·

Hello again.

I have applied this fix https://cgrenderdna.blogspot.com/2018/06/arnold-render-anisotropy-tangent-fix-uv.html

And seams cuts seem be fixed (but some anisotropy circular reflections appear)

Maybe this solution must be enabled by default in comming releases...

¿What do you think about this?

Thanks!


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Eden Exposito avatar image
Eden Exposito answered ·

Seems be related with a problem with Standard Surface shader and Specular anisotropy value. With 0 value seams cuts seems dissapear and with higher values the problem become more visible..

¿What is happening here?

Thanks

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