如何逼真的模拟自然景物一直是图形学中的一个热门研究课题。火焰、云、雪花等动态自然景物的模拟，在航空航天、影视广告、虚拟场景中有着广泛的应用。随着近年来研究的不断深入，各种自然景物模拟算法不断涌现，模拟结果也越来越具有真实感。其中，粒子系统方法是迄今为止被认为模拟不规则模糊自然景物最为成功的一种生成算法，本文深入研究了基于粒子系统的三维火焰模拟方法。 首先，本文对国内外已有的火焰模拟算法进行了阐述、分析和总结，并阐明了粒子系统在建模不规则自然景物方面的几个重要优点。 其次，深入讨论了基于粒子系统的三维火焰模拟方法，详细讨论了火焰模型中火焰粒子属性的初始化及其变化，包括火焰粒子的形状、大小、颜色、透明度、位置、速度、生命期等，并且讨论了火焰粒子的运动和绘制。采用面向对象的思想建立了粒子系统和粒子的数据结构。设计了火焰模拟系统的功能模块，将该系统划分为四个模块：粒子系统模块、粒子模块、纹理模块和运动场模块。在火焰绘制过程中，为了增强真实感，采用了纹理映射技术、公告板技术、混色处理技术。特别是为了表现火焰来回左右上下跳动的动态摇曳效果，在系统中增加了运动场。在运动场中重点讨论了重力和风力对火焰的影响。为了提高实时性, 在火焰粒子绘制中，一是采用四角面片代替点粒子的绘制方法，这样每一个面片可以代替几百个粒子；二是采用动态生成视点替用特效技术，提高了系统的运行速度。在论文的最后，探讨了提高粒子系统实时性的方法。 最后，采用Visual C++ 6.0为编程工具，三维动画环境由OpenGL支持，在Windows XP环境下开发了基于粒子系统的三维火焰模拟系统，模拟效果真实。

How to simulate natural sceneries vividly is always a hot topic in Computer Graphics. The simulation of dynamic natural sceneries, such as fire, cloud and snowflake, are widely used in navigation, spaceflight, movie, advertisement and virtual reality. With the development of research in this subject recently, kinds of simulating algorithms have been proposed, the results of simulating is becoming vivider than before. Among these algorithms, Particle System has been regarded as the most successful one for simulating irregular fuzzy natural sceneries so far. This paper investigates the method of three-dimensional fire simulation based-on the Particle System. Firstly, this paper introduces the previous algorithms of fire simulation, then analyzes and summarizes them. It also introduces several important merits of Particle System in modeling irregular natural sceneries. Secondly, this paper discusses the method of three-dimensional fire simulation based on Particle System. It discusses the initialization and variation of the attributes of fire particles detailedly, including shape, size, color, transparence, position, speed, life cycle and so on. It also discusses the motion and rendering of fire particles. It constructs the data structures of particle systems and particles by using object-oriented ideas. It designs the functional modules of fire simulation system and divides it into four modules: the particle system module, the particle module, the texture module and the motion field module. In order to enhance the third dimension, we use texture mapping, billboarding and the color mixture techniques for fire rendering. Especially in order to describe the dynamic wavering of fire, for example, it wavers left and right, up and down, the motion field is introduced into the fire system, we mainly discusses the effect of gravity and wind to the fire. In order to improve the performance of real time, on the one hand, we use each surface in stead of the dot particle to render the fire particle, so every surface can substitute hundreds of particles, on the other hand, we use the dynamically generated imposters technique, so the speed of implementation is increased. At the end of the paper, the methods of improving real time of Particle System are discussed. Finally, by using Visual C++ 6.0 as the programming tools and the three-dimensional animation is supported by OpenGL, the full system of three-dimensional fire simulation based-on Particle System is developed on Windows XP operating system and the effect of simulation looks realistic.