A mean string algorithm to compute the average among a set of 2D shapes

An algorithm to compute the mean shape, when the shape is represented by a string, is presented as a modification of the well-known string edit algorithm. Given N strings of symbols, a string edit sequence defines a mapping between their corresponding symbols. We transform these sets of mapped symbols (edges) into piecewise linear functions and we compute their mean. To transform them into functions, we use the equation of the line defining their edges, and the percentage of their length, in order to have a common parameterization. The algorithm has been experimentally tested in the computation of a representative among a class of shapes in a clustering procedure in the domain of a graphics recognition application. © 2002 Elsevier Science B.V. All rights reserved.