1. A system for identifying a face on a three dimensional test body on a stage by comparing an optical representation of the face with stored signals indicative of optical representations of comparison faces of three dimensional comparison bodies, said system comprising: means for illuminating said comparison faces sequentially and for generating and storing an optical representation of the relative amounts of white, gray and black areas on each comparison face. means for illuminating said test body in a first direction and for creating an optical image, means for receiving the optical image in a second direction oblique to said first direction, means for generating electrical signals representative of the relative amount of white, gray and black area as viewed in said second direction, means for generating a signature signal comprising information representative of said relative amounts of white, gray and black areas on the face of the test body, and means for comparing the signature signal of the face with the stored signals indicative of optical representations of the comparison faces to determine which face is being viewed.