Research On Edition And Management Of 3D Model In Virtual Geography Scene

The data organization and management in the virtual geography scene is important components of 3D data visualization in virtual geographical environment. The virtual geography scene, made of 3D virtual models, is the visualization expression of geography phenomenon essentially. So the construction, organization and management of 3D model data is a critical issue to be solved urgently in virtual geographical environment system.On the basis of former studies, this paper mainly focuses on the conversion of 3D model data, the simplification of 3D models, the construction of 3D model library, the edition and management in the virtual geography scene.At first this paper chose OpenFlight as the standard of 3D model data in virtual geography scene because it has been the standard data format in virtual simulation field. In order to apply the 3D model data of CAD in virtual geography scene. On the analysis of OpenFlight and DXF data structure, this paper raises the scheme of data transformation from DXF to OpenFlight. the program performed also. It is proved that the data are transformed completely and the results are reliable.Secondly the data quantity of 3D geometric models is so large that it is difficult to store, transfer and render. Thus it is necessary and significant to research on the simplication arithmetics for 3D geometric models. After analysis and studies on some simplication arithmetics all around the world, this paper proposes the method to evaluate the geometric importance of vertices in 3D model. Using the vertex geometric importance, this paper improves the model simplification arithmetic based on edge collapse. The result from experiment shows that the simplified-model by the algorithm of divisional envelope pitches can preserve the sharp features and have a higher resemblance with its original geometric model.Along with the enlargement of virtual geography scene scope and the increase of the models, the 3D model library system is an effective solution to manage and share 3D models. Based on the studies of structural frame of virtual geography scene, This paper explains the 3D model library system from the theory, the structure, the function, the traits, the reality technology and the running of the system in details. What's more, the paper takes the 3D model libray as the core and develops the prototype system, which includes the modules of 3D model edition and reconstruct, 3D model library management, virtual geography scene editon and management.Finally, the author make a conclusion of the whole thesis and some problems worthy for further studies.