A Quantitative Analysis of View Degeneracy and its use for Active Focal Length control

W e quantify the observation by Kender and Freudenstein [6] that degenerate views occupy a significant fraction of the viewing sphere surrounding an object. This demonstrates that systems for recognition must explicitly account f o r the possibility of view degeneracy. W e show that view degeneracy cannot be detected f rom a single camera viewpoint. As a result, systems designed to recognize objects f rom a single arbitrary viewpoint must be able t o function in spite of possible undetected degeneracies, or else operate with imaging parameters that cause acceptably low probabilities of degeneracy. To address this need, we give a prescription f o r active control of focal length that allows a principled t rade08 between the camera field of view and probability of view degeneracy.