The VRayOverrideMtl is a utility material
provided with the V-Ray renderer. It allows a surface to look in a different
way depending on whether it is seen through reflections, refractions or GI.
With this material you can get a fine control over the color bleeding,
reflections, refractions and shadows of the objects. For more info see the
Example section.
Base
material - this is the material V-Ray will use while rendering the
object.
GI material - this is the material V-Ray
will use while calculating the GI solution.
Reflect material - this is the material
V-Ray will use to render the object with, when the object is seen in
reflections.
Refract material - this is the material
V-Ray will use to render the object with, when the object is seen through
refractions.
Shadow material - this is the material
that will be used to render shadows cast from the object.