Distribution of this document is unlimited 13. ABSTRACT (Maximum 200 words) This thesis addresses the problem of visual recognition under two sources of variability: geometric and photometric. The geometric deals with the relation between 3D objects and their views under parallel, perspective, and central projection. The photometric deals with the relation between 3D matte objects and their images under changing illumination conditions. Taken together, an alignment-based method is presented for recognizing ob-jects viewed from arbitrary viewing positions and illuminated by arbitrary settings of light sources. (continued on back) 14. SUBJECT TERMS (key words) 15. NUMB.R OF PAGES object recognition correspondence 176