Shaohua Kevin Zhou Gaurav Aggarwal Rama Chellappa David W. Jacobs Appearance Characterization of Linear Lambertian Objects, Generalized Photometric Stereo, and Illumination-Invariant Face Recognition. 230-245 2007 29 IEEE Trans. Pattern Anal. Mach. Intell. 2 http://doi.ieeecomputersociety.org/10.1109/TPAMI.2007.25 db/journals/pami/pami29.html#ZhouACJ07