Research & Design Of 3D Visual Engine For City Planning

The 3D Visual City Planning System(3D-planner) is a 3D visual geography information system which is used mainly in city planning industry. In one hand, much more information of city planning are provided to the public to make them know about the current situation as well as show their wills, so that all the citizens can take part in the designing. In the other hand, it also helps the city planners to perfect the designing proposal.As the most important part of this system, the 3D visual engine will be researched in this treatise. Besides, how to design and implement this engine is presented as the focal point.First of all, this treatise gives a general overview of the concepts of city planning,3D visual engine,scene organizing,accelerating algorithm and etc.And then, after not only analyzing the 3D planner's current situation,working mode and developing direction but also comparing with some existing 3D GIS systems, the city planning oriented program frame of 3D visual engine has been provided based on Open GL technology.Further more, some key technologies, especially the data-scene organizing and graphic accelerating algorithm are researched as the focal points. (1) A Scene Graphs is used to structure a data tree.3D scene combines with terrain scene to form a data model directed at the planning industry. The data will base on the VRML standard format. Both organized data structure and accurately described truthful data can make the engine schedule data efficiently. (2) As a solution for displaying mass data efficiently, the accelerating algorithm which adopts View Frustum Culling(VFC) technology can accelerate the 3D scene according to its structure. Meanwhile, the retinal cone discriminant theory should be researched for simplified formula derivation.In a word, some primary methods of 3D visual engine designing are put forward concretely. Moreover, some explanation for pivot as well as the computer result of public virtually roaming system are given. And the last section sums up both the problems and researching direction definitely.