【作者】 王继民；

【导师】 朱跃龙；

【作者基本信息】 河海大学 ， 计算机应用技术， 2003， 硕士

【摘要】 近年来，在许多虚拟现实系统中需要动态仿真水流运动，为了增加系统的真实感，就要正确地对水流进行仿真，其关键是建立恰当的模型和采用适当的渲染算法。许多现有的流体模型只能单独描述流体的某些属性，不能同时描述流体的一些重要属性，如：速度，高度域等，而这些属性在很多与水流有关的仿真系统中是必不可少的；传统的光线跟踪渲染算法能够产生具有很强真实感的图形，但是不能够满足实时的需求。 本文针对上述背景，总结了现有的各种水流建模方法以及渲染算法的研究现状。在此基础上给出基于压力高度域的水流模型，并阐述了该模型的合理性。同时分析了Fresnel函数的特点，给出基于纹理映射和分段近似Fresnel函数的水流渲染算法。为了生成满足水流模型空间大小的纹理，本文给出了搜索带加速的WL纹理合成算法。最后在VC++和OpenGL环境中实现了一个简单的实时动态水流仿真系统。 本文讨论的模型能够描述水流的多种属性，这增加了模型的应用范围；同时渲染算法能够满足实时需求。进一步的工作是如何将渲染算法和硬件特性结合以进一步提高仿真系统的速度；同时在纹理中反映光照对水流表面的影响。更多还原

【Abstract】 Currently, in many Virtual Reality Systems, there is an increasing need for simulating the fluid behaviors dynamically. To obtain more realistic scene, simulating physically realistic fluid behaviors is very important. Many fluid models just present only one aspect of fluid, and can’ t present some important properties simultaneously, such as speed, heightfield etc. .which are necessary in many fluid simulation systems. Although the traditional raytraced-based rendering algorithms can obtain high quality graphics, they can’ t be used in Real-Time Systems.This paper investigates the existing fluid models and rendering algorithms firstly. Then, a pressure-based height field fluid model is proposed and the pressure to simulate the fluid surface height is justified. The rendering algorithms based on the use of texture maps and piecewise approximate Fresnel formula of reflection is proposed after analyzing the Fresnel formula. To get texture maps at appropriate size, an accelerated method for Wei and Levoy’ s basic algorithm (for short, WL algorithm) is presented. Finallly, a real-time fluid simulation system is implemented with VC++ and OpenGL.The pressure-based height field fluid model can present many important properties of fluid and thus can be used widely. A Real-Time System can be achieved with the model and rendering algorithms proposed in this paper. Further research is how to improve the speed of simulation system by considering the properties of graphic hardware and presenting the illumination in texture maps.更多还原