Pseudo-distance measure for 2D shapes based on turning angle

We describe a pseudo-distance function for planar shapes that can be used for similarity retrieval based on shape in image database applications. A shape is represented as a vector of turning angles, and the distance between two vectors is computed using a dynamic programming algorithm. We improve the method over previous similar approaches by allowing multiple starting points along the object perimeter. Results of shape retrieval to match either user hand-drawn shapes or stored object shapes in a database of approximately 2300 shapes demonstrate the methods capabilities.