The Geometrical Representation Of Anomalistic Objects In Virtual Reality System

Virtual Environment is an advanced interface, which provides some intuitional and natural perceptive means, such as vision, hearing, feeling, and so on. Users construct a set of realistic models with computer and then create virtual environment with 3D characteristic. With the rapid development of computer technology, virtual reality technology is used in more and more areas. In the meantime, it needs to generate realistic images in real-time. Especially for natural scenes, which have enormous data, generating realistic images in real-time has been the bottleneck and key point in virtual reality application areas.In natural scenes virtual reality system, the realistic degree of fog terrain wave and fire can affect users' immersion directly.In this thesis, we aim at solving the geometrical representation of some anomalistic objects. We try to combine the realistic representation and real-time control of the virtual natural scenes.In the real-life world, natural scenes always have plenty of surface textures and anomalistic shapes. In the process of simulating these natural scenes in computer, it is an impractical method to represent all the surface texture in detail only with some traditional computer graphics methods. For the limited distinguish ability of our eyes and computer display, the excessive detailed descriptions are useless. At the same time, the tremendous computing workload can embarrass the real-time display in computer environment. How to simplify the natural scenes with fire and fog is becoming a pivotal technique. With the continuously development of computer simulation technique and virtual reality application, natural scenes modeling has becoming more and more important.In the thesis, we take the virtual representation of anomalistic geometrical objects with stochastic characteristic as main contents, Such as the geometrical modeling of fire wave fog and cloud 3D terrain, etc.. These kinds of natural scenes do not have regular shape, but have stochastic and self-similar characteristic. So we take fractal technology and particle system technology astheory support and realization technique, it is the first step of our work; the second work is texture mapping to the models. Thus we can enhance the realistic of natural scenes, satisfy the requirement of virtual environment, and realize preferable combination of realistic images generating and real-time controlling of the natural scenes.The main work of this thesis includes: Introduce some correlative research background in chapter 2. Then introduce some corresponding research work on water modeling briefly, expatiate the generating method of water wave in chapter 3, viz. simulate water wave with physical modeling method. We use the integrated kinetic equations, take wave as countless compact water columns, simplify the top surface of these columns, and get the numerical result. Then put disturb on the water, and get the realistic effect of water. In chapter 4, we introduce fractal theory. In chapter 5, we give out a 3D terrain generating method and then walkthrough in it. Here we construct the three dimensional terrain with Chuan-Zhen method, in view of real-time request, we simplify the 3D model with LOD theory. In chapter 6, we introduce the particle system theory and then construct fire and cloud model with particle system. As practice, we change some characteristic parameters of particle system, and get some different scenes. Thus the whole content of this thesis is self-contained and applied. In chapter 7, we integrate all the above chapters, and construct a virtual natural environment with 3D terrain water fog and its walkthrough.