Research On Some Key Techniques In 3-D City Model

In 2D GIS, the objects in the real world are abstracted as point, line and polygon, and then are projected onto the plane. Because of its wide applicability, it is rapidly applied to all kinds of fields. The maturity of theory and technology promotes the standardization of 2D GIS. However, along with the scope and degree of GIS application become further, the limit inhere in the 2D GIS becomes more and more prominent, many fields, such as geology, mining engineering, ocean exploration and meteorology, require current GIS have the ability to process real 3D data. So 3D GIS becomes an important issue in GIS.City, acting as a political and economic and culture center of a region, is the area where GIS applications performed most profound. The comparatively maturity of 2D GIS make the demand for 3D functions more outstanding, many departments, such as city planning, environmental protection and pipeline pavement etc, all need GIS to provide 3D functions, so the concept of 3D City Model is put forward and relevant researches are performed.3D City Model (3DCM) is a model that is used to present all the urban objects in computer, it is the city described by computer. It frees the description of city from the routine planar map, and presents it in the 3D coordinate.However, the majority of 3D GIS software is still stay in the stage of visualization or animation creation at present, among which many key problems, like 3D data model, topology, modeling theory and database management, are still under development, which hinder the deep application of GIS to some extend. This thesis mainly studied the relevant theory and technology of 3DCM, put forward and exhausted the problems of topology, scale, visualization and cognition; on the aspect of technology, this thesis systematically discussed the methods and key technologies of 3DCM, and make a prospect and consideration about the development of 3DCM.