Toolbag 4 - Ray Traced Shadow Artefacts

Ricky

Hi,
I've recently moved up to Toolbag 4 and love the ray tracing capabilities, but keep getting these horrible shadow artefacts only when ray tracing is enabled. It's as if the lighting is looking at a hard-edged version of the model to light rather than taking into account the normals properly with the textures.
With ray tracing:


With raster:


• I've checked the tangent space for the model. it's set to 'Marmoset'. The model was made in Maya, and changing it to that makes no difference. No other option there fixes it. 

• Disabling 'Cast Shadows' on the mesh fixes it, but then means it wont cast shadows on itself. 

• Latest video drivers.

Any help would be much appreciated! 
Thanks,
Ricky

Ricky

Found out it only happens when I use HDR images for the skybox instead of jpegs

Ricky

Bump. I'm also finding this kind of issue with GPU VRay for Maya and in Substance Stager (all different scenes and models). I read somewhere someone say its an issue with GPU renderers, so not sure how to fix this other than changing the lighting setup. If anyone else is experiencing this or similar would be handy to know how others deal with it.

EarthQuake

This is generally expected. What you're seeing here is shadows cast from the low poly geometry. If the low poly geometry had more detail or was more smooth, you would see more smooth, detailed shadows as well. A few things you can try:

1. Edit the low poly model to have more detail/more closely match the high poly model
2. Sub-divide the low poly model in Toolbag
3. Consider adding a displacement map (along with sub-division)
4. Adjust the Shadow Offset setting in the Render object (Common panel)

AndyC_Art

Bump. Im having the same issue and I can confirm I dont need further subdivision for it to look good because its happening only on a specific part of  my model, by that logic everything in my model should look faceted but it doesnt, its only on a specific part, this bug is annoying

EarthQuake

@AndyC_Art as explained above, this is a fundamental property of ray-traced rendering. Shadow quality is dependent on the detail or smoothness of the geometry, which can't be faked with a normal map to make it appear more smooth than it is.

Please try some of the suggestions in the response before yours.

AndyC_Art

EarthQuake said:

@AndyC_Art as explained above, this is a fundamental property of ray-traced rendering. Shadow quality is dependent on the detail or smoothness of the geometry, which can't be faked with a normal map to make it appear more smooth than it is.

Please try some of the suggestions in the response before yours.

I would like to know this then, why is it that the highlighted areas shade correctly while the other area doesnt? why is it only on the part with the decal? its all similar poly density


 

EarthQuake

@AndyC_Art try reducing the intensity of the normal map in this area, or running a normalize filter on the normal map, it's possible that invalid normal vectors are being used here which could cause shading artifacts