Based On Three-dimensional Model Of The Virtual City

Today, with the development of computer technology and modern communication technology, great changes have taken place in the world by digital-technology and Internet technique. The digital and the digital city as most important part of information have developed rapidly, and virtual City support mutual interface as a visible platform. Virtual city is based on virtual reality technology and emulation technology, and is the merely form of expression. Nowadays, the research on virtual city is becoming one of the hottest problems. The paper is about the method of virtual city bring up the way of building model of three-dimensional space.Firstly, the paper reviewed the present situation about virtual city and virtual Reality technology and talked about the significance of building virtual city. From the paper we can see, the author mainly researched about the technology of building model, building environment model, three-dimensional space model, space analysis and so on. Building the-dimensional space model is the most important part in this paper. For the simulation of terrain, the author mainly adopted two methods Grid and TIN(triangulated irregular network) to simulate DEM and induce Delaunay triangle net algorithm, Delaunay triangle net update algorithm and constrained lines inserted algorithm to exhaust.For the object on the land, the author discussed the way of building space model based on geographical features and introduce in details different model of three-dimensional space such as TEN model, Octree model; The integration of three-dimensional space also is important problem in this paper. Gash exists in the three-dimensional space because the different of surface and object model, data structure organization and the separation of models. So we propose geometric seamless technique based on Grid and TIN and induce a new integration way to solve the problem between terrain and model under terrain. In the paper, we introduce two methods of Reality sensible and summary technology: texture mipping and level of Detail technique. Texture mipping takes image on the geometric surface of object and similar expresses the real object enhancing the sense of reality; LOD technique takes the different parts of scene into different way to describe object. For the object in the environment, we build some different detailed geometric models in the same time.Secondly, author presentetd that OpenGL programming under windows and reappear of virtual city. Under building three-dimensional city model, author combines sensible and summary drawing method and adopts visual C++, application of interface of three-dimensional image . By introduced model, we develop a simple system—virtual city system and proof it feasibility. In addition, it achieved three-dimensional dynamic roam .In the end, the paper summarized all full text and presented profound research.