SHAPE FROM SYMMETRY - DETECTING AND EXPLOITING SYMMETRY IN AFFINE IMAGES

We investigate the constraints placed on the image projection of a pla nar object having local reflectional symmetry. Under the affine approx imation to projection, we demonstrate an efficient (low-complexity) al gorithm for detecting and verifying symmetries despite the distorting effects of image skewing. The symmetries are utilized for three distin ct tasks: first, determining image back-projection up to a similarity transformation ambiguity; second, determining the object plane orienta tion (slant and tilt); and third, as a test for non-coplanarity amongs t a collection of objects. These results are illustrated throughout wi th examples from images of real scenes.