Matching flexible polygons to fields of corners extracted from images

Abstract

We propose a novel efficient method that finds partial and complete matches to models for families of polygons in fields of corners extracted from images. The polygon models assign specific values of acuteness to each corner in a fixed-length sequence along the boundary. The absolute and relative lengths of sides can be either constrained or left unconstrained by the model. Candidate matches are found by using the model as a guide in linking corners previously extracted from images. Geometrical similarity is computed by comparing corner acutenesses and side lengths for candidate polygons to the model. Photometric similarity is derived by comparing directions of sides in candidate polygons to pixel gradient directions in the image. The flexibility and efficiency of our method is demonstrated by searching for families of buildings in large overhead images. © Springer-Verlag Berlin Heidelberg 2007.