Study On Three Dimensional Visualization Of Underground Pipeline

With 3DGIS developing, 3DGIS can effectively implement information management of underground pipelines. But display of underground pipelines is still 2 dimension or 2.5 dimension. In order to observe complex distribution and corresponding spatial relation of underground pipelines, know accurate and intuitive distribution of underground pipelines, it is our problem to be solved that to display underground pipelines using 3D visualization technique.3D visualization of underground pipelines included 3D display of the terrain and pipelines. The terrain model and pipeline model of constructing and visualizing theories and algorithms were mainly discussed in the paper. The user interfaces was created in Object-Oriented language in VC++6.0 MFC, terrain and pipeline have been modeled and visualized by projecting, blanking, geometric transforming, lighting etc operations, then we have realized 3D visualization of underground pipelines.The terrain model has displayed by DEM. On the basis of studying advantages and disadvantages of Grid and TIN, DEM has realized by TIN according to characteristics of used terrain data. The two TIN generating algorithms were introduced: convex hull and constriction method and point-by-point insertion method. On the basis of summarizing advantages and disadvantages of two algorithms, the point-by-point insertion method was improved, and it made TIN simply generate and easily realize. And DEM was constructed by using improved algorithm, then realistic and fidelity of DEM was improved by lighting and texture mapping.To visualization of pipelines, it was mainly studied that pipeline segment modeling and connecting between two pipeline segments, on the basis of studying pipeline by processing methods, simplifying and abstracting pipe segments and nodes. The Pipeline segment was modeled by using cylinder, and connection between pipeline segments had two kinds: pipeline segments with the same radius and pipeline segments with different radius. To the first kind, the ring segment was inserted between two pipeline segments, and to the other kind, the ring segment and truncated cone. The smooth pipeline model could be established by shearing transforming, and pipeline system visualization was even more close to reality by lighting and material rendering.In a word, we were studied visualization of underground pipeline, starting key technology of 3D visualization. During the study, we improved connection methods between pipeline segments. The method did not make 3D pipe segments smooth connection and improve realistic of pipeline.