EQUILATERAL POLYGON APPROXIMATION OF CLOSED CONTOURS

Numerous algorithms have been suggested for computing polygonal approx imations of closed contours. We present an algorithm which as a unique feature creates polygons which are equilateral, that is, whose edges are all of the same length. This allows one-dimensional shape descript ions to be derived using the interior polygon angles. Conceptually, th e algorithm is an optimization framework for finding the minimum energ y configuration of a mechanical system of particles and springs that r epresent the contour points, the polygon vertices and their interactio n. In practice, the dominant points are detected on the Gaussian smoot hed contour and used to seed an initial polygon. Nonlinear programming is then used to minimize the system energy subject to the constraint that adjacent vertices must be equidistant. The objective function is the sum of a curvature weighted distance between each vertex and a set of contour points associated therewith. Experimental results are give n for closed contours obtained from grey-scale images. Copyright (C) 1 996 Pattern Recognition Society.