Accession Number : ADA259602


Title :   The Alignment of Objects with Smooth Surfaces: Error Analysis of the Curvature Method


Descriptive Note : Memorandum rept.


Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE ARTIFICIAL INTELLIGENCE LAB


Personal Author(s) : Basri, Ronen


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a259602.pdf


Report Date : Nov 1991


Pagination or Media Count : 20


Abstract : The recognition of objects with smooth bounding surfaces from their contour images is considerably more complicated than that of objects with sharp edges, since in the former case the set of object points that generates the silhouette contours changes from one view to another. The 'curvature method', developed by Basri and Ullman (1988), provides a method to approximate the appearance of such objects from different viewpoints. In this paper we analyze the curvature method. We apply the method to ellipsoidal objects and compute analytically the error obtained for different rotations of the objects. The error depends on the exact shape of the ellipsoid (namely, the relative lengths of its axes), and it increases as the ellipsoid becomes 'deep' (elongated in the Z-direction). We show that the errors are usually small, and that, in general, a small number of models is required to predict the appearance of an ellipsoid from all possible views. Finally, we show experimentally that the curvature method applies as well to objects with hyperbolic surface patches.


Descriptors :   *CURVATURE , *ERROR ANALYSIS , *CONTOURS , *PATTERN RECOGNITION , MODELS , EDGES , SHAPE , ERRORS , SILHOUETTES , VISUAL PERCEPTION , AXES , IMAGES , ALIGNMENT , SURFACES , ELLIPSOIDS


Subject Categories : Cybernetics


Distribution Statement : APPROVED FOR PUBLIC RELEASE