Example 1: Secondary rays bias

 

Example 1: Secondary rays bias

This example shows the effect of the Secondary rays bias parameter. The scene below has two planes that occupy exactly the same region in space. Due to this, V-Ray cannot resolve unambiguously intersections of rays with these surfaces. The first image shows what happens when you try to render the scene with the default settings. You can see the splotches in the GI solution, caused by the fact that rays randomly intersect one or the other surface:

 

In the second image below, the Secondary rays bias is set to 0.001, which offsets the start of each ray a little bit along its direction. In effect, this makes V-Ray skip the problemmatic surface overlaps and render the scene correctly: