The Curvature Texture node can be used to alter the look of the edges of a surface (figure 1).
Figure 1: The Curvature node applied to a scene object
Figure 2: The Curvature node used as the Amount input on a Mix Texture node
Mode
Determines the type of curvature to sample.
Strength
Determines the overall strength of the curvature effect.
Radius
Specifies the maximum area affects by the curvature effect.
Radius Map
Determines the proportion of the maximum area affected by the curvature effect.
Offset
Specifies the offset from the surface used to sample the neighboring geometry.
Tolerance
Determines the tolerance for small curvature and small angles between polygons
Spread
Controls the ray direction with respect to the normal of the surface where 0 means the curvature is sampled straight in the direction of the surface normal, and 1 means the sampling rays are shot perpendicular to the surface normal.
Include Object Mode
Determines which objects should be included in calculating the curvature value.
Invert Normal
Inverts the normal direction when calculating the curvature value.