Matching with Shape Contexts
Given two shapes, $N$ samples are drawn from the edge elements of the shape. There are no specific constraints on these points - they can be either on the internal or the external contour of the object. Moreover, they also need not correspond to keypoints for the shape (such as maxima of curvature, inflection points, etc.), and although desired that the samples be uniform in spacing, this too is not a rigid criterion. ...