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中国图象图形学报 2001
Simplification and Aggregation of Polygon Object Supported by Delaunay Triangulation Structure
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Abstract:
Polygon simplification and aggregation play an important role in automatic cartographic generalization. Design of this kind of operator algorithm requires to consider geometric and topological characteristics, and needs to find a spatial data model to support extraction of interesting adjacent area, such as bend feature, gap region between polygons, neighbor area between islands within polygon. In this process, detection of neighbor relation is a key step. Delaunay triangulation structure is a powerful tool of spatial neighbor analysis due to its circumcircle principle and closest to equilateral properties. Applying Delaunay triangulation principles, this paper presents a spatial data model and constructs formal selection strategies. On the basis of constructed model, the study systematically investigates the problem of polygon bend simplification, exaggeration as well as neighbor polygon aggregation. The paper divides polygon simplification into steps: islands selection, concave part fill, shallow area skeletonizing, concave part exaggeration and convex part clip. As for polygon aggregation, it is classified as three cases: absorbing, enclosing and separating and three methods are discussed respectively. Some of operator algorithms are presented in the paper and corresponding experiment results are illustrated.