Research On3D Wire Modeling And Physical Simulation

Recently, as the rapid development of virtual reality and computer graphics, highfidelity, high sense of reality and high intelligence have been three importantcriterions for virtual reality platform, and, to some extent, have leaded the way ofdevelopment of virtual reality applications. To be specific, high fidelity means makingthe surface of3D models highly similar to real world by using proper illuminationalgorithms and tessellation techniques. High sense of reality has two implications. Forone thing, models in virtual world are able to depict real physical and chemicalfeatures. For another, it is expected to enhance the immersive sense of users byemploying external devices, such as stereoscopic glasses, multi-screens andhuman-computer interactive devices etc. High intelligence aims to solve someunexpected problems confronted during the process of virtual world softwareexploiting by using artificial intelligence techniques or labor replacing methods, forexample, low efficiency of artificial modeling has been conflicting with therequirements for mass models of virtual world.Considering the special requirements of simulation applications like, tube net ofvirtual city, harbor scenes, lifting simulation and navigation scenes, to improve thescene of reality and intelligence, we focus on exploring the3D reconstruction,rendering and physical simulation of tubes, string and chain. Then, we acceleratethese algorithms with GPU shader. Alas, we integrate the wire simulation into i4Cityplatform and VR4MAX software. Finally, we assess the feasibility and efficiency ofour methods in real applications. Our work includes some aspects below.1.3D reconstruction and rendering of tubeAnalyzing the structure of the3D tube model, we implement the3Dreconstruction of tube in GPU geometry shader, by regarding directed line segmentsas the central axis of tube, automatically generating vertexes of pipe ring, conductingthe triangulation of tube surface and establishing the link rules between these vertexes. Then, we study the discrete LOD algorithm based on user-defined model refining.Also, we implement modified Phong illumination model in GPU shader to improvethe efficiency and sense of reality.2.3D reconstruction and rendering of chainFor chain, one kind of special model, which is consisted of same chain ringmodel with free movement, we employ method of repeat rendering to build chainmodel and render it. It is a good way to use interpolation algorithms, such as linearinterpolation, spine interpolation and parabola interpolation, to solve the problem ofinitially rough data. In this paper, a kind of semi-automatic perception method is usedto implement seamless link between two chains.3. Physical simulation of chainSince chain models are quite complex, and the number of chain rings is too huge,a kind of particle representation method, in which chain ring models are divided intomany spherical particles, and momentum of particles are calculated separately, isapplied to simulate the physical features. The physical simulation is implemented inGPU shader, which enables computations execute concurrently.4. Integration and applicationSimulations mentioned above are integrated into i4City platform and VR4MAXsoftware as an isolated module. The results of them are assessed in two applications,chemical process pipe line system and virtual harbor system.