When creating cycles Shaders using glossy or refractive in combination with the bump node you sometimes run into strange black areas. These artifacts are cause by “badly” reflected/refracted rays. When using a normalmap (or using smooth shading for that matter) we basically use fake normals instead of the real ones, those fake normals however can possibly direct the ray in directions where it cant go (i.e inside the mesh) at least figuratively. Whilst this is no big problem in most cases it would be useful to have a safe and sound alternative to the Bump Node that does not create those black spots. There are some implementations of this here but they tend to be rough estimations and seem to have cases where they do not work.
So this is the Problem:
and this is what my solution looks like:
there are still some problems I want to fix however it seems to be a promising start. So here is the node group I created:
In this comparison the Bump strength and Distance where booth set to 0.7 and the height was set to be a voronoi texture. Questions and Ideas are appreciated.