SYSTEM FOR AUTOMATIC GENERALIZATION OF TOPOGRAPHIC MAPS

Key words: 
• map generalization system /
• map database /
• rule library /
• topographic map

Abstract: With the construction of spatial data infrastructure, automated topographic map generalization becomes an indispensable component in the community of cartography and geographic information science. This paper describes a topographic map generalization system recently developed by the authors. The system has the following cha-racteristics: 1) taking advantage of three levels of automation, i.e. fully automated generalization, batch generalization, and interactive generalization, to undertake two types of processes, i.e. intelligent inference process and repetitive operation process in generalization; 2) making use of two kinds of sources for generalizing rule library, i.e. written specifications and cartographers' experiences, to define a six-element structure to describe the rules; 3) employing a hierarchical structure for map databases, logically and physically; 4) employing a grid indexing technique and undo/redo operation to improve database retrieval and object generalization efficiency. Two examples of topographic map generalization are given to demonstrate the system. It reveals that the system works well. In fact, this system has been used for a number of projects and it has been found that a great improvement in efficiency compared with traditional map generalization process can be achieved.