Research On The Technology Of Virtual Scene Rendering And Application In Portal Crane Simulation System

Virtual reality technology has been a hotspot of research since the 1990s.The quick development of network technology provides a physical basis for the research on distributed and multi-users virtual reality system. Rendering technology of virtual scene is the key to the virtual reality system. Nowadays there are two means that can be used to produce virtual scene. That is IBM(image-based method) and MBM(model-based method). However, these two methods have their own defects. The former can't be real-timely operated. The latter has expensive modeling cost and long rendering pipeline , what's worse, it requires a great deal of 3D data transfer through network and high network bandwidth in the distributed environment. The major goal of this paper, based on deep research on geometry-based modeling and image-based method, is to keep off the difficulties of these two ways, make full use of the advantages of them and simultaneously integrate the research on network real-time rendering to launch a research on a hybrid virtual scene producing technology, that is, IBRAC technology. The idea of this technology is that 3D models of virtual scene are constructed in the server end in light of the method based on geometry, while virtual scene is portrayed both in the server and client end in accordance with the method based on image.Those primary technologies of rendering virtual scene based on geometry are discussed in this paper, ranging from constructing virtual scene's 3D shape, transforming, 3D view to the algorithms for eliminating hidden panel and clip. We establish a simple virtual scene of portal crane, accomplish the primary functions of the server end in the prototype of the distributed virtual training system for portal crane drivers, and describe both implementation and running environment of this system. Then, those image-based methods are studied deeply in this paper, including the method based on stereo vision, panorama, view interpolation and plenary optic function. Especially, we attach importance to the producing process of panorama and cinematograph calibration, matching method of homonymy points and coherence of perspective relationship. Finally, according to IBRAC technology, this virtual training system for portal crane drivers is analyzed and designed. The performance of this system is represented as well.