Research On Organization And Visualization Of Global Terrain Data

In recent years, with the rapid development of computer science and information technologies, organization and visualization of global terrain data have been applied in more and more fields, in the same time several three-dimensional earth browsers have been released. However, there is no mature theory or standard technology framework having been proposed in this field. Existing systems often have some defaults in data organization, view scheduling or spatial calculation. This thesis focuses on the key technologies of global terrain data organization and visualization, with the purpose of constructing a visualization system with global consistent data structure, and efficient data manage mechanism. The main work and contributions are described as follows:A spherical division method based on quaternary triangular mesh and longitude\latitude division strategy was proposed after deeply studying and analysis of many classical division strategies. This method can not only provide a global uniform continuous distribution, but also retain the advantages of convenient data transformation, so that lay the foundation for further multi-resolution modeling.In order to solve contradiction between huge dataset and limited computer processing ability, and achieve real-time visualization, a multi-resolution data model is proposed for constructing, organizing and using the global terrain data in form of basic data blocks. And a longitude\latitude associated coding method is also present to enhance the coding and indexing performance.Based on the principle of data block resolution self-adaption, a novel Level-of-Detail method is proposed to realize global terrain rendering, whose complexity is independent of the amount of global terrain data. Several essential spatial calculation equations are also derivated, which enable the LOD algorithm to perform in the global ellipsoid environment.Based on the technologies such as out of core data scheduling, GPU friendly rendering, triangle strip simplification, layout storage optimization, we optimized the data organization model and LOD rendering algorithm, a global terrain data organization and visualization system GeoEarth is designed and implemented, using the above algorithms and framework. The GeoEarth system could also be applied in many other applications as a fundamental platform.Summarily, this thesis studies key technologies on 3D organization and visualization of global terrain data, which can be used to realize fast construction and real-time rendering of huge dataset, which builds solid ground for other relevant applications.