Odd smoothing error

[Draydin_r]

Hi Guys,

I've been working on a project over the last couple of days useing the new octane 2.0 for lightwave and I've noticed a smoothing error when I apply bump images to glossy objects. If I remove the bump the smoothing fixes itself. I can't send over the file due to NDA but this seems to be happening whenever I use the glossy node on a smoothed surface. Thankfully you have displacements to help out with the bumps for fuzzy fabric

But overall please let me know if this is something you can look into.

Note: The rendering looks simple due to me using sample ambient lighting for a quick preview.

Cheers,
Draydin_r

The chair with bump applied...

... and without.

[Draydin_r]

Also, when smoothing is disabled and bump remains. The error disappears.

[juanjgon]

I am going to check this issue ASAP. Thanks for report it.

-Juanjo

[gordonrobb]

Isn't this just the problem that bump is pretty much useless on a curves surface in Octane - because of the shadow terminator problem?

[juanjgon]

Nope. There is a problem with the reflection rays in the glossy and specular materials when the object has normal vectors from the host application, it has smoothing and a bump map. This problem is also there in the Standalone, even with the standalone material preview scene.

I am going to ask about this issue to the Octane developers.

-Juanjo

[juanjgon]

This is the answer from the developers:

"This is a problem with the scene, the bump map is very low resolution, noisy and high contrast, and you generally don't see bump maps under an uniform environment like that. The artefacts arise because the bump map power is too high, i.e. it introduces too much distortion on the normals of the object.

There is a slight darkening around the edges of the torus even without bump, that's a different issue in Octane. You can mostly hide it by setting glossy depth to 3 instead of 2."


So please, in your scene try to lower the bump map image power, and set the glossy depth in the kernel to 3, 4 or 5 to see what happens. In my donut scene, set the glossy depth to 4 removes the artifacts.

-Juanjo

[Draydin_r]

Bump map is currently 1024x1024. I tried 2048x2048 with no difference.

Currently using PMC with Gloss depth of 24.

SmoothingError_Settings.PNG (11.17 KiB) Viewed 3295 times

Reducing Bump value has no effect at 0.5

Reducing Bump value to 0.25 does reduce the effect but also loses the look that I was going for to begin with.

Also, in DL Sample Ambient Glossy Depth 16 does nothing to reduce the Artifacting.

SmoothingError_Settings_V2.PNG (9.38 KiB) Viewed 3295 times

This wasn't a problem in 1.50. I wonder what changed? Is it something that can be fixed?

-Draydin_r

[juanjgon]

Can you please send to me this object (or only a part of it, where you can see the artifacts), your scene setup and the bump file you are using?

You can email it to me: [email protected]

Perhaps this is not the same problem I found with my donut scene.

Meanwhile perhaps your best workaround could be use your bump map as displacement map if possible.

-Juanjo

[NemesisCGI]

Time the render problem got sorted by OTOY... Please.

[gordonrobb]

From another post, I tried reducing the RayEpsilon, and it seems to get rid of the problem. Have you tried that?