Efficient Partial Shape Matching of Outer Contours

This paper introduces a novel efficient partial shape matching method named IS-Match. We use sampled points from the silhouette as a shape representation. The sampled points can be ordered which in turn allows to formulate the matching step as an order-preserving assignment problem. We propose an angle descriptor between shape chords combining the advantages of global and local shape description. An efficient integral image based implementation of the matching step is introduced which allows detecting partial matches an order of magnitude faster than comparable methods. We further show how the proposed algorithm is used to calculate a global optimal Pareto frontier to define a partial similarity measure between shapes. Shape retrieval experiments on standard shape databases like MPEG-7 prove that state-of-the-art results are achieved at reduced computational costs.