When using a coarse approximation of an object and imitating a smooth surface (by bending normals away from the geometry normal) you may find shadow artifacts.
To correct this try the following:
- Use fine approximation to fit the surface more precisely
- Disable Casts Shadows for the object to avoid self-shadowing (see
Render Stats)
- Use a separate shadow casting object to cast shadows onto other objects
- Adjust the Ray Offset attribute on a per-object basis (see
mental ray Ray Offset)
- Use shadow maps with a Bias instead of raytraced shadows, if possible (see
Shadow Map Attributes)