Noise by Polygons at the same Position

[rs3d]

I just used a "Melt" modifier on a sphere with a reflecting/refracting VRayMtl.

Where the polygons are at the same position/height a strong noise comes up,
probably because VRay doesn't know which polygon comes first...

Is there a parameter to prevent this behavior of the renderer?

Thanks in advance, Robert

[vlado]

You can try setting the "Secondary rays bias" parameter to a small positive value like 0.001; also make sure that the material is double-sided, and, if reflective, that the "Reflect on back side" option is enabled.

Best regards,
Vlado

[rs3d]

Thanks Vlado! "Secondary rays bias" helps, "Reflect on Backside" had no direct influence...

Best, Robert

[joconnell]

You could probably put a push operator with a really small value on top of the melt modifier too - it'll force the polygons away from each other a tiny bit.

[rs3d]

@joconnell: Good idea, but it isn't specifically about "Melt", but any
transformation that causes such overlays ... the Ray Bias works great.