Arnold GPU Albedo Issue

[lbuonaiu]

I'm trying to render my animation in Arnold GPU but these weird lines are showing up in the albedo AOV and thus the beauty aov. The textures don't look like this and the issue doesn't show up in the CPU Renderer. Is this a known issue or are there any suggestions?

[Stephen.Blair]

I see aliasing along the edges and noise (like gray pixels), is that the issue?

What's the difference in the sampling settings between CPU and GPU?

What shaders are you using? Is it Toon? What version of MtoA?

[lbuonaiu]

Thanks for the reply

Its a very subtle issue and its not the aliasing. There's gray lines across Woodys face that don't show up in the CPU renderer only the GPU. Its in the test render attached to this. The issue is on his face, it becomes a big problem on the beauty pass. Both the CPU and GPU were on the same sample settings. I'm using an aiStandardSurface, not toon. MtoA 5.4.5

[lbuonaiu]

I double checked my reference file and it was actually a Blinn but I switched it to an aiStandardSurface and the issue is still present

[Stephen.Blair]

What's in the standard surface? SSS?

I do wonder if more samples on the GPU will help. GPU almost always needs more AA samples because we don't do ray splitting (so it's AA samples only, no diffuse samples, specular samples, SSS samples).

(A Blinn is translated into a standard surface)

[lbuonaiu]

I don't believe there is any SSS. Here's a picture of my render settings and setup at 20aa and 25 max aa with adaptive sampling. It's not done rendering in the picture but as it is getting closer to being done the lines don't go away. The material also only has an image texture going to the color and that's it.

[Stephen.Blair]

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@lbuonaiu wrote:

I'm trying to render my animation in Arnold GPU but these weird lines are showing up in the albedo AOV and thus the beauty aov. The textures don't look like this and the issue doesn't show up in the CPU Renderer. Is this a known issue or are there any suggestions?

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The CPU render has similiar artifacts, at least in that screenshot. Is that because the CPU render is still progress?

[Stephen.Blair]

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@lbuonaiu wrote:

I don't believe there is any SSS. Here's a picture of my render settings and setup at 20aa and 25 max aa with adaptive sampling. It's not done rendering in the picture but as it is getting closer to being done the lines don't go away. The material also only has an image texture going to the color and that's it.

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In that case, is it down to the texture? What if you stick that texture on a sphere?

Or what if you take the head geo and remove/hide everything else in the scene, so that it's a very simple scene. 

[lbuonaiu]

It's seems to be that the texture is not the issue but the geometry and the rig are the problems since the sphere and the texture look fine. What's weird is that the CPU Renderer doesn't have this issue.

[lbuonaiu]

I think those cpu render artifacts are just from noise. The GPU Rendering consistently creates those lines so I believe it has something to do with the deformations on the geometry. It’s just so weird that it only happens on the gpu one.