Chaos Corona Forum
Chaos Corona for 3ds Max => [Max] I need help! => Topic started by: north_1 on 2021-12-28, 16:17:19
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Hey, guys)
Really need your help.
I have a mesh modeled in Blender and imported in 3ds max.
Basic studio setup, one physical camera, one targeted corona disc light, same CoronaPhysicalMtl on the mesh and the studio plane. 1 smoothing group used by the whole mesh.
And a shading bug I can't fix.
I've made the same setup in Blender and it looks clean. The mesh is really straight and simple.
I've tried every possible way I knew (different export/import settings, fbx/obj, reseting/unifying normals, with/without studio, etc) and it didn't help. There's nothing special about this mesh, no edge weights, no custom normals, no flipped polys, nothing. The most special about it is this bug).
I'd really appreciate your help with finding the solution.
Thank you!
3ds max 2020, Corona 7.
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Have you tried the Weighted Normals modifier?
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Did you check normals with edit normals modifier, to be absolute sure that all vertex normals are indeed reseted to average?
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@romullus yes, I did. didn't help.
@hurrycat I putted Weighted Normals in the Modifier stack, applied it and exported like fbx. nothing changed.
thank you for your replies.
I attached scene files, maybe this way it will be easier.
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the issue seems to be on reflection not on mesh
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I exported the object from Blender and imported it to 3ds Max, then reseted its normals to average. There's no issues with normals from Blender and both objects renders just fine. I think the issue is somwhere in your export/import settings. Attaching the max file, so you can merge the object from there in case you can't solve your issue the other way.
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@romullus thank you for your time! I've change the background color to black and putted the targeted disc in your scene without changing/adding anything else. and it's weird, but this is what I've got. if the light is behind (or in front of) the model - there is still a bug. but if the light is moved to the side - everything looks nice.
@Lorenzos thank you for reply. there is nothing in the scene except the model and the light. model uses default CoronaPhysicalMtl. so I really don't know how can there be issue with the reflection.
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at the same time it looks ok with different hdri's and at different angles.
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I took a closer look at the object and it seems it's combination of two things - slight imperfections in mesh itself (nothing extraordinary, just some vertices slightly misaligned here and there) and extreme light condition, that amplifies every slightest surface imperfection and makes it look like huge mess. As you can see from your further tests, at more reasonable lighting, everything looks just fine. It's very hard if not impossible to make triple A surface with polygonal modelling and you can always find such angle where small imperfections will be magnified and will look ugly. All in all, i think there's nothing wrong with your model.
Edit: turns out it's shadow terminator. If you go to devel/debug settings and turn off shadow terminator fix by setting shadow shift to 1.0 then the issue is gone and the mesh will render fine at any lighting condition.
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@romullus thank you very much, I really appreciate your help.
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No problem.
You can report your case as a bug, shadow terminator fix is meant to fix things and not brake them - maybe devs can analyze your mesh and see if things can be improved in later versions.