Methodology for Developing a Database of Geometric Patterns to Better Support On-the-fly Map Generalization

Cartographic generalization has been a research topic for more than thirty years. In spite of recent advances, a complete automation of this process still faces fundamental problems. Furthermore, recent needs such as web mapping and Spatial On-Line Analytical Processing (SOLAP) require geospatial data that are generated on-the-fly at any scale. This requires processing times and a degree of automation that today's automatic generalization algorithms cannot reach with all data types. This paper presents the concept of geometric patterns and explains how they can be built and stored in a pattern database for further use in a map generalization process. Geometric patterns are typical shapes that are representative of several occurrences of a cartographic object class. They support simple operations such as rotation, translation or stretch and allow adapting them to the exact geometry of individual objects.