Shape matching using polygon approximation and dynamic alignment

Abstract A method for classifying closed planar shapes is presented. A shape is preprocessed and represented by several ordered sequences of vertices which are obtained by using polygon approximation algorithms with different approximation error criterions. A dynamic alignment algorithm is used to compute the similarity index between two sets of shape descriptors. The shape recognition process is hierarchical and is invariant to rotation, translation and scaling. Classification experiments using noisy contours and objects are performed and satisfactory results are obtained.