| Virtual Reality is a kind of advanced man-machine interface, which contains real-time stimulation and interaction by sense channels of vision, hearing, touch, smell, taste and so on, with characteristics of interaction, immersion and imagination. In VR system, process during which the cognitive way of sense organs is stimulated actually, and established and imaging data are rendered directly and exactly, is called establishing scene(or environment), or creating virtual scene. In virtual scene, 'realism' contains geometry realism, behavior realism and illumination realism. It is the base of realizing '3I' characteristics of VR system, and making users be personally on the scene.For designing a virtual reality system, the crucial problem is how to create realistic environment, which contains 3D virtual scene, stereo and so on, besides related hardware equipment. Among information accepted by human, vision information quantity is biggest, almost 60%, and visual reaction is quickest. So if the scene is too simple, users might feel false, but if the scene is complicated, the real-time performance of graphic engine will be affected and the interactive difficulty will be increased. As a result, creating realistic and reasonable scene model, real-time and dynamic display besides, is very important to create vitual environment. It is one of the most important research field in Virtual Reality.With object of Beijing Jiaotong University, this paper contains research and experiement on how to realize realistic virtual scene based on vision sense, and also completes system optimization. Concrete contents of this paper are as follows:1. Analyzed and compared three kinds of virtual scene modeling methods—modeling method based on graphics rendering, image, and both graphics and image; studied texture mapping in detail; decided to adopt modeling method based on both graphics and image.2. Studied and summarized rendering technologies of realistic virtual scene—illumination models, polygon rendering algorithm, ray tracing algorithm, blanking algorithm, LOD management, and DOF technology.3. Proposed a flow of creating virtual scene models. After module partition, completed terrain, buildings and plants modeling, model optimization, and scene settlement. Thereinto, model optimization is one of the key to realize realistic virtual scene. 4. Studied the scene rendering process and collision detection technology in real-time simulation, simulated the whole optimizing virtual school scene in Vega environment, and also realized real-time system cruising. |
