粒子系统是实时模拟三维地形场景中具有真实感的降雨情景的一种有效方法。本文基于粒子系统的基本原理分析并提出了适用的雨粒子系统和雨粒子的属性，采用了把雨粒子产生区域定义为一个视图体顶部的外接长方体、用象素点和直线作为雨粒子的形状、降落过程的重力作用模拟、用粒子组实现雨粒子的连续补充和雨粒子的降落高度检测等新的方法及算法。试验结果表明，该方法能有效地再现三维地形环境场景中的降雨景象，在满足实时交互漫游的前提下表现出较强的真实感，具有一定的实用价值。

During the course of present investigation,a method for simulating the rain in 3D terrain scene in the real time is proposed,using particle systems. The applicable attributes have been analyzed with reference to the rain particle system and the rain particles, in accordance with the basic principles of particle systems. Methodological approach includes the employment of feasible techniques or algorithms such as defining a cube outside the top of the view frustum as the generation shape of rain particles, using a point in pixels and a subsequent line as the shape of a rain particle,simulating the gravity influence in the course of rain particles' put down,replenishing continuously rain particles using particle groups and, testing the fall heights of rain particles in the real time etc. The results of experimentation have proved that this method is more effective in the representation of rain in 3D terrain scene which also found to be realistic at the time of satisfying basic need of real time interactive navigation.