The Conceptual Schema of Map Generalization from Spatial Mapping Perspective
AI Tinghua(Laboratory of Digital Mapping and Land Information Application Engineering, Wuhan University,Wuhan 430079,China)
From the point of view of mapping transformation, this paper presents a map generalization conceptual framework which regards generalization as two kinds of mapping procedures: spatial entity mapping and spatial relationship mapping. According to the number of changes in the participating entities, spatial entity mapping is classified as 11, n1, nm mapping. Spatial relationship mapping is described as a composite relationship transformation of the components: topology, distance and orientation. The concept 'spatial relationship resolution' is introduced to describe spatial relationship related constraints. Based on the 9 intersection model, the cardinal direction model and the isodistancerelationship model, the paper gives three sorts of relationship resolution representations for topological, distance and orientation relationship respectively. The behavior of the two mappings in map generalization is discussed and a special emphasis on the spatial relationship abstraction is placed compared with the traditional generalization conceptual model.