Torrance-sparrow off-specular reflection and linear subspaces for object recognition

TitleTorrance-sparrow off-specular reflection and linear subspaces for object recognition
Publication TypePatents
Year of Publication2005
AuthorsThornber KK, Jacobs DW
Secondary AuthorsNEC Laboratories America I.
Patent Version Number10/230,888
Date Published2005/05/31/

The Torrance-Sparrow model of off-specular reflection is recast in a significantly simpler and more transparent form in order to render a spherical-harmonic decomposition more feasible. By assuming that a physical surface consists of small, reflecting facets whose surface normals satisfy a normal distribution, the model captures the off-specular enhancement of the reflected intensity distribution often observed at large angles of incidence and reflection, features beyond the reach of the phenomenological broadening models usually employed. In passing we remove a physical inconsistency in the original treatment, restoring reciprocity and correcting the dependence of reflectance on angle near grazing incidence. It is noted that the results predicted by the model are relatively insensitive to values of its one parameter, the width of the distribution of surface normals.