Patent ID: 7058217

Claim:
A method of recognizing objects under various lighting conditions comprising: (a) providing a database comprising a plurality of three dimensional models, (b) providing an input image, (c) orienting each three dimensional model relative to the input image, (d) determining, for each three dimensional model, a rendered image which is most similar to the input image, said determining step comprising: (i) deriving a reflectance function that describes an approximation of the set of all possible rendered images that each three dimensional model can produce under all possible lighting conditions, said rendered images including both diffusely and specularly reflected light; and (ii) optimizing the reflectance function to determine rendered image of each model that is most similar to the input image; (e) computing a measure of similarity between the input image and each optimal rendered image; and (f) selecting the three dimensional model corresponding to the optimal rendered image whose measure of similarity is most similar to the input image, wherein the reflectance function employs a broadened-specular reflectance model that accounts for the angle between the direction of observation and the direction of perfect specular reflectance, said broadened-specular reflectance model axially symmetric about the axis of perfect specular reflection.