Research On The Key Technologies About Visualization Of Spatial Information--Case Of 2.5D,3D And Multidimensional Visualization

With the fusion of "3S" and the increasingly extensive use of spatial information process technologies, visualization of spatial information, spatial analysis, spatial data mining and visualization based knowledge discovery have gradually developed into important means and key technologies of information processing. Visualization can help us understand spatial information and analysis spatial rules in a more comprehensive way, it can even assist decision-making during macroscopical planing process in the application world of spatial information. In this paper, the author selected three typical research directions for further research, including 2.5D, 3D and multidimensional information visualization. To be more specified, the author turned these three kinds of problem into three detailed research directions, namely visualization of terrain, visualization of stratum datasets and regular datasets, and visualization of multidimensional information (which has more than 3 thematic dimensions). This paper does a deep research on the above three-detailed research areas and discusses the design and realization of the algorithms corresponding to them thoroughly.This paper consists of seven chapters. The first one is preface. It discusses the research background, the purpose and the meaning of this paper and the research dynamic both in domestic and international range. The general research approach of this paper is also presented in this chapter.The second chapter introduces the methods of data processing. Firstly, it presents a new way of interpolation, which is particularly adaptive to plot the non-gridded research field - multiquadric method, this method uses quadric functions as the basic function of interpolation. The benefit of this method is its mathematical simplicity and its consequent ease in programming. Secondly, it brings out a new 3D interpolation method-hypersurface spline method, this method extends the surface spline method of 2D interpolation into 3D space. The numerical implement procedure of this method is introduced in this paper.Based on the state of arts in terrain visualization domestic and foreign, chapter 3 studies the algorithms of terrain visualization based on DEM data in depth, the mainresearch results are as follows:? It brings out a method that generates random terrains based on Perlin noise function and furthermore, it issues the method of constructing LOD (Level Of Details) for terrain using Perlin noise too.? It proposes a terrain grid simplify method based on Morton coding. This method firstly simplifies the original data according to the principle of Morton coding, then renders the 3D terrain using these simplified data, as result, when rendering, the DEM grids are also simplified. The merit of this method is it can compress the DEM data and simplify the terrain grids without precision reduction.? It presents an improved real-time continuous LOD algorithm based on unfull quadtree. This algorithm firstly simplifies the DEM data by using Morton coding and stores the simplified data with an unfull quadtree. Then, it builds the real-time continous LOD based on this unfull quadtree according to the relationship between viewer position and space error of grid object. The author brings out a method named "find the neighbors layer by layer" to patch the cracks between different layers and the procedures to find the different type neighbors are presented in this paper. Finally, it wipes off the invisible grids through back-culling algorithm.? It presents an improved LOD algorithm based on ROAM. The improved algorithm brings out an thought of "First Division Then Modeling", it first divides the large DEM data into smaller sub-blocks and then establishes the real-time continuous LOD based on them according to the relationship between the viewpoint location and the space error generated when splitting. In order to make this LOD technology adaptive to any DEM data, the auhtor uses "None Right-isosceles Triangle" as the unit to simulate the terrain and the method of LOD...