Constructor And Visualization Of 3d City Models

Currently, the construction and application of 3D City Model (3DCM) is the main tendency of international GIS and its related subjects . Multipurpose 3DCM has a wide application in the fields of achitecture, civil engineering, traffic, geology,city planning, network and multimedia etc. in the future. In addition, with the development of "digital earth" and "cyber city", the constructional concept of 3DCM is becoming more and more important.The research status is firstly analysed in this paper. After an analysis and comparing of existing 3DCM, the methods for constructing topographic model , building model , road model, water system model etc. are focused on the discussion. The TIN and GRID modeling method are applied for topographic model, a layer-combined model based on triangle partition is presented for building model and a independent triangle partition is presented for the other models .All these models are combined to topographic model in the end .Based on these models, the author discussed how to realize the visualization of 3DCM.The method of 3D-Visualization is adopted object-oriented language (Visual C++) and 3D graphic tool (OpenGL) to develop. Meanwhile, in 3D-scene , some functions of spatial analysis and interactive operations have been realized. And, a testing application system of 3DCM is developed, which includes TIN model construction, the creation of contour, spatial coordinate query, section-cutting, measuring distance and area, 3D visualization and operation about topography and building etc. The purpose of developing testing system is to demonstrate the correctness of 3DCM based on the visualization. Finally, the result of the testing and 3DGIS research direction is put forward to investigate generally.