Research On Map Algebra Model And Methods Of 3D Relief Generalization

Relief is one of the most important features on a topographic map. As an importance sub-problem of map generalization, relief generalization has become a bottleneck that has restricted the development and widely applications of DEM (Digital Elevation Model). For many years, researchers have been working on relief generalization in the field cartographic.In this dissertation, it is stated from the analysis of the existing research on relief generalization sys -tematically that Interactive approach based on the generalization of the terrain's structure lines is more useful than intelligence generalization, because there are many logjams in the field of artificial intelligen -ce at present. And then, a new 3D relief generalization approach based on map algebra is presented to overcome two disadvantages of the existing approaches.On the one hand, there is a natural law that the undulation of the ground in three- dimensinal space is the direct reason that rainwater flows under the ground, the dissertation puts forward an new idea that we can master the three-dimensional characteristic of the ground with drainage analysis from the point of vie -w of hydrology, and takes it as the main clue to maintain the harmony between relief and river network during the process of generalization and the process that DEM data can be self-organized and self-structur -ed. There are concrete steps, firstly, automatic extraction of river network using the digital flown line model under the ground from DEM or contour map and taking the river network as the valley lines for structured generalization of relief. Secondly, adopting the accumulation of falling water as the parameter for estimating the weightiness of valley lines to considering the three-dimension characteristic of relief when importance valley lines are selected.On the other hand, aiming at another natural phenomena that there are relations of distinct hiberarchy among the terrain structure lines just like a tree, a concept of macro-structure of the structure lines is put forward in this dissertation, at the same time, a concrete method named "FenCengZhaiYe"is presented. It is a process for data to be self-organized and self-structured.Catching above two key clues and applying map algebra, the dissertation focuses on several key pro -blems including foundation and estimation of high fidelity DEM, foundation of the digital flown lines model of terrain, automated extraction of terrain structure lines, getting the sequence of the terrain feature points, estimation parameter and method of the weightiness of valley lines, implement of macro-structure, digital drainage area analysis and reshape contour lines.The dissertation consists of 6 chapters and the content of each one is as follows.Chapter 1, introduction. First, this chapter sets forth the special meaning, characteristics and the research significance of relief generalization in digital environment. Second, the dissertation reviews and summarizes the research developments in the field of relief generalization systematically. Finally, the chapter presents the main idea, research method and technology route of the map algebra Model for 3D relief generalization.Chapter 2, map algebra. This chapter introduces the main theory and methods of map algebra, inclu-ding the algebra viewpoint of map, the signs theory, the organization and expression of data, the innova -tion of the map algebra, comparing map algebra with other analogy research, and so on.Chapter 3, automatic extraction of the terrain structure lines. This chapter expounds two viewpoints: 1) The DEM with high precise and high fidelity is the ground for future terrain analysis.2) Getting the sequence of the terrain feature points is a crux of the generation of terrain structure lines, and compact DEM is the only way to do it. The chapter also brings forward a digital flown lines model of terrain in which we can get the flown line of any raindrop under the ground based on contour map or DEM. Toward the problems of automatic extraction of the terrain structure...