On Data Processing Of 3D Modeling Of Digital City

3D urban modeling is a new trend of Urban Geographic Information System (UGIS) which attracts more and more attention both for academic research and application development.3D Building modeling is a foundation of the urban model in 3D UGIS. Based on the requirement of geometry theory and 3D urban modeling, this paper presents a method to establish building model of digital city by applying CSG/B-rep hybrid method, especially in spatial relationships. A group of CSG entities is created for single building from image as the first step of the method herein. Then spatial relationships are established according to those featured objects, that is vertex, edge or face of architectures. CSG entities are assembled together by applying constrains in 3D spatial and they are solved by least-square method. The paper summarized themethod of obtainning data in the single building. B-representations are created as final results. Proposing spatial constrain relations of some solids during this course. Then the spatial relationships are described within the single building model on the basis of this model. The method of solid assembleing in building model has brief introduced. A prototype system is implemented by VC++ and OpenGL. 3D building model of main teaching building of TYUT are tested as an example. Through the contrast of the model, the necessity of data processing is verified in single building modeling. Through data processing, reducing the complexity of modeling, it has improved the dependability and practibility of the model.