Research Of Overpass 3D Modeling Software Based On Virtual Reality

The overpass is the city's traffic hinge. It plays an important role in solving the increasingly crowded urban traffic conditions. With the development of national economy the urban overpass design concepts have undergone a fundamental change. The modem urban overpass is not only a traffic establishment which lighten the city's traffic pressure but also a landscape of the city. The design of the overpass must be harmonious with the city's environment. This requires us to treat the overpass as a 3D entity and to design it as a whole. However, the overpass is different from ordinary roads and bridges, it has complex shape, and many routes intertwined in the air. So it is difficult to image what the overpass looks like and to judge whether the design of it is excellent. In this paper, we will introduce the concept of virtual reality to bridge design.3D modeling technology will be used to constitute the overpass model, so that the idea to design the overpass as a whole will come true; Meanwhile, 3D model will be supplemented by accessorial means of transportation and urban landscape to construct a virtual environment. Roaming through the virtual vehicle along the overpass we can feel directly and vividly the effects of its linear design and coordination with the urban environment.This paper focuses on the following development work:1) We studied the the approach to abstract the data structure of every object in the overpass system. Introduced the concept of scene database to the BM3D's data storage strategy. Especially studied the road intersection's data structure to prepare for the follow-up study, like traffic flow simulation.2) This paper presents the use of feature-based Technology in developing the overpass modeling system and the parametric modeling method.3) The approach to enhance the fidelity of the virtual overpass scene is discussed. A combination of geometric-based modeling and image-based modeling technology is used to create the model of the overpass. Texture mapping algorithm and Virtual roaming technique was used to increase the scene fidelity.4) Applying the results of these studies, we developed an overpass three-dimensional modeling software—BM3D. BM3D already has the capability to model the space overpass.the fidelity of the model has researched relatively high standard. Some roaming functions have been achieved too.5) We modeled the Madian overpass which was located in Beijing by BM3D testing the software feature. The result state that we can evaluate the effects of the overpass's linear design and the coordination with the urban environment directly and vividly.