3d Gis Visualization Technology In Terrain

With the continuing development of the application of GIS,the former methods,which deal with three-dimensional data in 2D manner,couldnt meet the needs of practical applications any longer. Users want to process,analyze and display the geographic information in manner of dynamically interactive three-dimensional visualization. At the same time,with the maturing of 2D data model and data structure techniques,the development of graphics theory and databases techniques,etc. it is possible for prosperous development of three-dimensional GIS. In the different phases of construction and maintenance for three-dimensional GIS,three-dimensional visualization will be involved in anywhere as long as three-dimensional objects exist,for example,in the process of input,edit,store,management and output of three-dimensional objects. Therefore,the visualization of three-dimensional objects is essential in the whole construction process of three-dimensional GIS. The research of three-dimensional virtualization techniques is the foundation for the implementation of three-dimensional GIS.Based on lots of advanced results of computer graphics,modem mathematics,computer science and topography,etc. this thesis discussed the theory,techniques and arithmetic of three-dimensional terrain visualization in three-dimensional GIS,such as terrain modeling techniques for digital elevation model,basic theory of three-dimensional terrain visualization,dynamical three-dimensional terrain display with simplified model,and spatial query methods within three-dimensional terrain maps. Among these techniques,combined with concrete requirements for visualization in flood control decision-making system,this thesis emphasized on the following aspects:1. Algorithm of terrain visualization by using scanning terrain map as texture;2. The simplified algorithm of view-point related multi-resolution terrain and the extended algorithm while its data are distributed like a band;3. The visual application of spatial query technique in the field of vector elements overlapping and the simulative evolution of flood.