Approximation of polygonal maps by cellular maps

Abstract

The approximation of polygonal thematic maps by cellular maps, an important operation in geographical data processing, is analyzed. The data organization used for representing the polygonal maps is a widely used segment-based data structure, where class labels identify the regions bordering each segment on either side. The approximation algorithm presented operates on such an organization, eliminating the need for the recognition of region boundaries. Each segment is examined only once. The versatility of the new organization is further illustrated by the outline of algorithms for area computation and point inclusion. The algorithm is applied to a set of soil maps converted to computer-readable form by means of a coordinate digitizer.