The Method And Theory Research On Automated Map Generalization Of City Settlement And Road Network Applying Delaunay Triangulation Network

With the development and further application of GIS in all fields of society, especially with the development of digital earth and Internet technology, the standard that users demanded for GIS is higher and higher. The existed GIS technology has difficulty in meeting the need of information society, and one of the most important reasons is that GIS can't resolve the problem of increasing and decreasing of vector data information of spatial objects brought with the change of map scale, namely the problem of automated generalization of spatial objects in GIS.Traditional map generalization in handwork has achieved a series of relatively perfect theory and method. At present, the digital map generalization is being on the stage of man-machine conversation. Therefore, how to apply the theory and method, which has existed for reference to research and achieve the automated generalization of spatial objects in GIS , has becomeone of the hot research points in GIS research fields recently.This thesis put the research emphasis on the theory and method concerning automated generalization of spatial objects applying delaunay triangulation and voronoi diagram, and the main contents are as follows:l.The existed main problem of achieving automated generalization of spatial objects and the key technology of realizing scaleless GIS were discussed based on the analysis of the character and present research situation of map generalization and digital map generalization, by which the research aim and significance of this thesis was embodied.2. A kind of model, which adapt to multi-scale map generalization of city settlement, was given based on the analysis of the partition methods of spatial configuration of city, the models of map generalization applying triangular network and the meaning of different generalization operators.3. Based on the analysis of TIN data structure applied frequently at present, a kind of data structure was presented to create delaunay triangulation in the second development environment of MapX. The feasibility of this data structure was proved by the realization of delaunay triangulation, constrained delaunay triangulation and voronoi diagram. Advantages and disadvantages of extracting different kinds of points of settlementsto create delaunay triangulation were analyzed during the course of generalization.4. The methods, with regard to extracting road center line, partition of street block and generalization of settlement in street block applying delaunay triangulation, were given based on the model of multi-scale generalization of city settlement.The ideas of multi-scale automated generalization of settlements in the street block were proposed based on delaunay triangulation applying gravity points of settlements, and the example was demonstrated.5. A generalization system of settlements in the street block was accomplished applying Mapx in VC++ based on the theory and method discussed in the thesis. The main functions include: *.gst file open/save as module, map tools module, Delaunay triangulation /Voronoi diagram module and the partition of street blocks module.