Modeling And Software Acceleration Techniques Of Complex Virtual Scene In Hydraulic Engineering

Generating a really convincing virtual scene and quickly rendering the scene is one of the most challenging research aspects in virtual reality field. To generat and render the realistic and real-time scene, which is needed in projects as "3D dynamic Simulation System", the theory and algorithms are studied on 3D modeling, scene interaction and software acceleration regarding visibility judgment and mutiple level of details for complex scene in this paper. Main work and research outcome of this paper are as follows:(l)The methods for building digital elevation model and object model are discussed in hydraulic engineering. Based on edge features picked up from image and backproject transformation, a method of hybrid modeling with 3D graphics and image is presented in this paper.(2)The techniques of 3D scene interaction, collision detection and picking up 3D object are studied. A new solution method for incorporating pre-detection and precise detection,and estimating motion parameter of viewpoint is presented to handle problems arising from collision detection in interactive walkthrough. The simple and efficient methods for picking up 3D objects are also discussed in this paper.(3) After culling algorithms based on object space and image space coherence are compared, a rapid algorithms is presented for incorporating BSP tree and major occluder, and accelerating image calculation through frame coherence.(4)In light of the need for real-time display of complex scene, the scene model of mutiple level of details with toplogical structure modification is built. After model simplification algorithms based on vertex clustering and vertexs collapse are discussed, the paper presents an adaptive simplification algorithm for dividing mesh by means of octree, and provides a real-time rendering method for incorporating view-dependent algorithms and view-independent algorithms.(5)The paper has made a close study of the existing simplification algorithms of muti-resolution level of details for terrain. A new muti-resolution rendering algorithm for terrain based on adaptive quadtree and view dependent algorithms is presented.Speedy simplification algorithms based on incorporating node block simplification in quadtree and vetexs simplification in the block is proposed in this paper.(6) According to a concrete instance of virtual scene system for hydraulic engineering, the paper analyses the frame structure of the system, provides methods for the caculation of water quality and water quantity, the construction of scene and scene tree, and management and simplification of the scene data. An instance of virtual scene system for hydraulic engineering related to a concrete project is given in this paper.