Hierarchical description of two dimensional shapes using a genetic algorithm

A description method for arbitrary two dimensional shapes is proposed in this paper. When a 2D shape is given as a silhouette, its structure is automatically approximated by the use of a set of rectangles by the proposed method. Sizes, positions and rotational angles of the rectangles which approximate adequately the given 2D shape are searched by a genetic algorithm; GA. In our coding of GA, a chromosome of each individual is a bit string corresponding to parameter sets of several rectangles. Through a generation iteration, accuracy of approximation of the given 2D shape is improved. The total number of rectangles to be used for description is assumed to be given before shape description. By changing the total number of rectangles, hierarchical description of given 2D shapes is achieved. This method can be applied to shape description and object recognition in the field of computer vision and to abstraction of 2D shapes in the field of artistic applications by the use of computers.