Rendering bug on one object only

[stevesideas]

My colleague has come across a very odd bug that I've never had before. I've tried a number of different things to try to resolve it but cannot work out the issue.

Basically there is some issue with shadows/GI. If I turn GI off it renders as it should. With GI on it becomes faceted with very odd shadow issues.

File attached. Max 2016

I've tried merging into a new scene. Merging the mesh into a new mesh/poly. Checked for double faces, checked for backface culling, checked for welded vertices. Re-created the dome light as I know sometimes that can be buggy. Reset vray renderer. The model was created on an educational version of max but I brought it into my commercial version and the same thing happened.

error_01.zip

[Margarita.Stoeva]

Hello!

The problem is actually in the geometry of the object. Its faces are duplicated and fit perfectly. If you go to the element level of the Editable poly you can click the object in the viewport to select one of the two copies and move it to the side. You can delete it if you don't need it. Or you can keep the scene as it is and set the Secondary rays bias to 0.01 (it's located in Render Setup >> V-Ray >> Global Switches >> Advanced mode).

Best regards,
Margarita

[stevesideas]

Thanks for taking a look at this. I thought I checked for co-planar faces yesterday. All working now. Thanks