This page provides information on the Curvature Map.
VRayCurvature is a texture that effectively samples the underlying mesh, and render a gradient based on a surface's curvature.
A region around each shaded point is sampled with additional rays (similar to VRayDirt) and all additional normals are averaged to get a "smooth" normal at the original point. This normal is used to compute the resulting color. The color at each shaded point is a greyscale value: darker values are dents (or holes), lighter values are peaks. The parameters should be adjusted by trial and error since they generally depend on the scale used, hence the defaults might not be appropriate in some cases.
UI Path: ||Material Editor window|| > Material/Map Browser > Maps > V-Ray > VRayCurvature
Subdivs – Controls the number of samples around each shaded point.
Sample spread – Controls the radius of the sampled region
Min/Max Output Color – Allows the output color to be mapped to a range that is different than 0..1 (makes the output texture darker or lighter).