3D Visualization Of Geo-potential Model (EGM96)

With the development of space technique, the geo-potential model, determined from satellite measurements and surface gravity observation, has been improved continuously, with higher resolution and precision. Geo-potential model is a three-dimensional entity, but it is showed in the style of formula or isoline graphics. So, 3d visualization of geo-potential model data has not keep up with the academic study. It is needed by academic study of the earth's gravity potential and is the foundation of Digital Earth.We have designed and implemented the software of 3D visualization of Geo-potential model, EGM96. There are two parts in the research:1.The requirement analysis and data analysis have been done. We designed the structure and functional models and built up the application software in single computer or double computers and double projectors environments without any GIS platform supported.2.With the base of the software being built up by C/C++ Source code and the 3D graphical interface following OpenGL, we implement all the functions of functional models. Some problems are settled in the study: 1) Adopting the idea of dividing the earth into two parts, it is easy to implement the process and calculate the vector. 2) Dynamic changing the scale of geoid undulations and the radius of the earth, the video mode of the earth figure is improved. 3) According to the theory of map projection, we establish the corresponding relations of the spatial points and the texture ones. This way also enriches the texture mapping methods of the computer graphics which only has columnar or spherical rules. This way also improves the precision of texture mapping. 4) Combining the techniques of partition and division method based on grid datum which may be interleaved, we can accelerate the real-time rendering of 3D scenes of multiple of details.