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Dimensional GIS objects in three-dimensional space abstracted as points, lines , surfaces , and projected onto the plane on the expression of this model has broad applicability , it was quickly applied to various fields , theoretical technologies mature of the two-dimensional GIS increasingly standardized . However, as GIS applications in the expansion of the breadth and depth of the limitations inherent in two-dimensional GIS is increasingly prominent , more and more areas , such as geology, mining , marine , meteorological departments , require GIS to handle true three-dimensional data capacity. The study of three-dimensional GIS become an important direction of development of the GIS . City , is a regional political, economic and cultural center , is also the most GIS applications , the most profound areas . The relative maturity of the two-dimensional function makes the three-dimensional features become more prominent in many sectors , such as urban planning, environmental protection , pipeline laying , require GIS with three-dimensional features , resulting concept of a three - dimensional model of the city and its research . The computer 3D city models (3DCM) the expression of all fixed objects in the city , described the city 's three-dimensional computer model . It allows the description of the urban landscape to get rid of a regular expression based on the plan and three-dimensional mock-ups and replace them with computer-aided three-dimensional representations . However, most of the three-dimensional GIS software visualization and animation on many key issues , such as : three-dimensional data model , topological relations , modeling theory and database construction , has not yet formed a unified understanding and maturity model , which to some extent hindered application of GIS deep . In this thesis, the theory and technology of 3D city models , topological relationships , scale and visual cognition theoretically elaborated ; technical level , the system construction methods and key technologies of 3D city models the prospect of the development of 3D city models and thinking .
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