Theory And Algorithms For Spatial Data Fusion And Visualization

The paper studies the theory and algorithms of space information fusion and visualization and focuses on the theory and implementation process of the key techniques and algorithms such as intelligent selection of multi-source remote sensing image fusion method, efficient organization and management of massive terrain data, real-time rendering of terrain data, efficient and accurate rendering of 3D vector data and clipmap-based rendering of global terrain data, and so on. A prototype system of space information fusion and visualization is realized and introduced in the dissertation. The main contents of the paper are as follows:1. The major problems to be solved by space data fusion are pointed out aiming at the special target of space data visualization. The technological process of multi-source remote sensing image fusion and basic theory of the popular pixel-level fusion algorithms are expounded and the correlative experiments are carried out. The evaluate methods of fusion quality are dissertated and the common selection tactics of evaluation index are presented. The theory of knowledge simplification and decision in rough set are introduced, and the intelligent selection of multi-source remote sensing image fusion method is realized.2. Based on the tile pyramid model and quadtree tile-index, the principles and methods of efficient organization and management of raster DEM and DOM are discussed. On the basis of the above, the scalable multi-pyramid terrain model is put forward to fulfill the integrated management and display of terrain data sets in different areas or with different resolutions in the same area.3. On the basis of raster DEM tile pyramid model, the inferablity and normal cone of the vertex are introduced, and the construction method of terrain tile TIN model based on geometric error and visual preservation is put forward. After analyzing the relationship between terrain data error and its screen error, the error control scheme based on the criteria of symmetrical hausdorff distance for terrain TIN model simplification is presented. To improve the rendering efficiency of terrain, the method of inter-rotating connection triangle strip generation algorithm for raster terrain tiles is put forward, as well as the strip-optimized oriented triangle strip generation algorithm for TIN terrain tiles is introduced.4. The real-time rendering tactics for tile pyramid model based terrain data is proposed, which includes the precise calculation and area control of the terrain scope in the view frustum, the optimal resolution rule based tiles-searching approach for terrain rendering, the management of terrain tiles buffer and the method to repair the visual gaps between the terrain tiles.5. Through analyses of the artificial stereo visual principle and the common stereo projection display methods, the plan of passive stereo projection display for 3D scene based on common dual-monitor graphic card and image splitting principle is put forward, which can greatly reduce the hardware cost of stereo display.6. The basic principle of the texture-based and geometry-based method for rendering 3D vector data is discussed. The optimization of texture-based rendering method is realized by using the perspective reparameterization similar to that applied in perspective shadow mapping. The principle of stencil shadow volume is introduced, and an efficient rendering algorithm for 3D vector data is realized, which has the pixel-level accuracy in screen space.7. The terrain rendering scheme based on plane geometry clipmap is explained. The principle of spherical clipmap, the discretization method of the clipmap level and the selection of the available clipmap layer are focused. The real-time rendering method for global terrain data based on the combination of spherical clipmap and terrain tile pyramid model is proposed.8. On the basis of the theory and algorithms above, a space data fusion and visualization prototype system is constructed. The framework, data flow, components of module and main functions are introduced, some experiment results and application demonstrations are also showed.