The Research Of Physical-based Modeling & Behavior Property 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. The third dimension here refers to not only graphics but also models' physical and behavior properties. So, under the precondition of satisfying realistic images, we also need a good real time property in graphics rendering and rapid response. But the realistic images generating is the primary problem. Especially for research on physical and behavior properties, has been the bottleneck and key point in virtual reality application areas.In the virtual reality system, the model must have some basic properties such as mass, weight and inertia. For some special applications, flexibility , friction and collision must also be described. All these can affect realistic of the virtual environment and the users' immersion seriously, and affect the whole design impact consequently.This thesis solves the description of models' physical and behavior properties in virtual environment; and improves on the traditional LOD algorithms so that it can satisfy the description of models' physical and behavior properties, thus we can get a good combination of realistic scenes generating and real time controlling.Any object in the real world has its' mass, it generates inertia, gets gravitation from other objects, and meets Newtonian three laws. When the motion tracks of two objects intersect, they may collide and have interference. Before and after their collision, they meet law of conservation of momentum and law of conservation of energy. Now, their motion states will change, such as their motion velocities, accelerations and motion directions. It is very clumsy to solve these problems with the traditional computer graphics method. It needs thedesigner to set some key frames manually, and at every key frame, the designer should also set the object's motion property according to his experience or scientific compute results. Then computer gives some interpolatory values and realizes the whole movie. Though a lot of commercial soft wares have some intelligence and can set the interpolatory values to achieve users' requirement in some degree, these soft wares can't satisfy users' requirement well, especially when users want to express their interactive desire.This thesis solves the description of models' physical and behavior properties in virtual environment; the thesis also takes emphasize on objects' physical properties from classical mechanics point of view, and researches the objects' behavior. The base of traditional computer graphics does not support objects' physical properties modeling, so, before modeling for the objects' basic physical properties, we build a bridge between these two knowledge, traditional computer graphics and physical properties modeling. We hope to abstract these physical variables, and express their physical properties satisfactorily by taking good use of the existing computer graphics productions. On the bases of these, we give computer graphics models of some basic physical variables, such as time, mass, force, velocity and acceleration, etc.. Thus we can build an integrate system. Then we can do some research work about the models' behavior properties, such as collision , collision response and invert kinematics, and so on. For taking good uses of these research productions in virtual design, virtual manufacture , games and entertainment, we give a whole set of develop tools, which are very convenient and flexible. By using the develop tools, users can build a virtual environment with physical and behavior properties on the bases of traditional computer graphics. At last, this thesis also gives out an improved LOD method. The traditional LOD algo...