On the appearance of translucent edges

Edges in images of translucent objects are very different from edges in images of opaque objects. The physical causes for these differences are hard to characterize analytically and are not well understood. This paper considers one class of translucency edges - those caused by a discontinuity in surface orientation - and describes the physical causes of their appearance. We simulate thousands of translucency edge profiles using many different scattering material parameters, and we explain the resulting variety of edge patterns by qualitatively analyzing light transport. We also discuss the existence of shape and material metamers, or combinations of distinct shape or material parameters that generate the same edge profile. This knowledge is relevant to visual inference tasks that involve translucent objects, such as shape or material estimation.National Science Foundation (U.S.) (IIS 1161564)National Science Foundation (U.S.) (IIS 1012454)National Science Foundation (U.S.) (IIS 1212928)National Science Foundation (U.S.) (IIS 1011919)National Institutes of Health (U.S.) (R01- EY019262-02)National Institutes of Health (U.S.) (R21-EY019741-02