A Framework for Automatic Landmark Identification Using a New Method of Nonrigid Correspondence

ÐA framework for automatic landmark indentification is presented based on an algorithm for corresponding the boundaries of two shapes. The auto-landmarking framework employs a binary tree of corresponded pairs of shapes to generate landmarks automatically on each of a set of example shapes. The landmarks are used to train statistical shape models known as Point Distribution Models. The correspondence algorithm locates a matching pair of sparse polygonal approximations, one for each of a pair of boundaries by minimizing a cost function, using a greedy algorithm. The cost function expresses the dissimilarity in both the shape and representation error (with respect to the defining boundary) of the sparse polygons. Results are presented for three classes of shape which exhibit various types of nonrigid deformation. Index TermsÐCorrespondence, critical points, polygonal approximation, automatic landmarks, flexible templates, point distribution