Occluding edges in apparent reversal of convexity and concavity.
Certain undulating surfaces have an ambiguous relief which may appear as convex or concave. The direction of relief is generally held to depend primarily on assumptions about the direction of illumination. It is suggested that this does not apply to pictures with relief features with occluding edges.
D003867:Depth Perception; D006801:Humans; D008029:Lighting; D009903:Optical Illusions