Large-scale Three-dimensional Ribbon Terrain Visualization Technology

Three-dimensiona(l3D) terrain visualization technology, which is one of the hot research topics, nowadays receives extensive attention. For roads, canals, and large oil and gas pipeline projects, the landscape along the two sides of projects within a certain range presents strip distribution with massive amount data, high direction, complex landscape and high quality engineering requirements. How to achieve three-dimensional visualization of strip terrain and improve the quality of surveying and mapping products based on the surveying and mapping results of road and pipelines is vital important. The visualization of large-scale 3D strip terrain involves computer graphics, digital image processing, computational geometry and many other disciplines, and combines many technologies such as data collection, terrain modeling, terrain simplification, and large-scale terrain data management and landscape simulation.The representations of digital terrain model as well as three typical algorithms to construct Delaunay triangulation are studied in the thesis. Moreover the large-scale 3D strip terrain simplification techniques including Progressive Mesh (PM) algorithm, Real-time Optimally Adapting Mesh (ROAM) algorithm and structure-based quadtree simplification technology are studied. And organization and scheduling technology of terrain texture are discussed. Further the comparison between three types of data sources related with the large-scale strip terrain (satellite remote sensing data, digital terrain maps and discrete point data) are given. According to the resolution differences of the three data sources, we proposed fast reconstruction algorithm of terrain visualization technology utilizing DWGDirect technology. Lastly, Creator / Vega and OpenGL combined engineering scheme are selected after analysis of several common terrain visualization schemes.The research arises from mapping project of the oil and gas pipelines of the Southwest Company of SINOPEC. Based on the results of surveying and mapping the pipeline, a real time 3D strip terrain visualization prototype system with high Sense of reality,automatic roaming function and many display modes are constructed adopting VC++ 6.0 and OpenGL as a platform, Creator as the modeling tool and Vega as the simulation tool. According to actual needs of the project, we also implements following functions: distance measurement of strip terrain, locating and displaying spatial coordinates, querying of the topographic features providing strong support for pipeline's integrity management and security management.Finally, conclusion and further work direction of 3D terrain visualization are given in the last section of the thesis.