【作者】 刘芳；

【导师】 李从信；

【作者基本信息】 大庆石油学院 ， 计算机软件与理论， 2008， 硕士

【摘要】 自然景物模拟技术是计算机图形学领域具有挑战性的课题,在航空航天、影视广告、室外设计、虚拟培训中有着广泛的应用和关注。由于自然景物几何结构复杂,运动规律不规则,很难用传统的欧式几何的方法来描述,因此目前研究中存在很多问题。雪、雨和云是三种典型的自然景物,在日常生活中随处可见,在虚拟环境中也必不可少。本文主要针对这三种典型的自然景物的模拟进行研究。本文首先分析了自然景物的特点以及由其特点决定的模拟的复杂性,讨论了自然景物模拟常用的几种方法。深入研究了粒子系统理论,结合降雪的特点,对降雪过程进行了基于粒子系统模型的模拟。针对降雪环境的模糊问题和雪花落地的积雪现象提出将雾化效果应用于降雪的虚拟环境中的方法。在雪粒子模型的基础上,结合降雨的特点和空气动力学理论对降雨进行了模拟。对雨滴落入水面形成的水波纹问题进行研究,改进四点水波纹算法,提出适合实时渲染虚拟环境的八点水波纹线性模拟算法。本文设计并实现了基于Perlin噪音的体积云的模拟算法,实现了卷云、积云和层云的模拟。由于Perlin噪音对云的物理活动的模拟还有所欠缺,因此本文设计并实现了基于细胞自动机理论的云的动态模拟算法,实现了云的生成、消失以及风吹云的动态效果模拟。在云的消失过程中引入消失概率变量,解决了云的缓慢消失以及消失后的再生成问题。更多还原

【Abstract】 The technology of natural phenomena simulation is a challenging problem in computer graphics. The people in many fields, such as aviation and spaceflight, movie, TV, advertisement, the design of outside and virtual train, show great concern about the development of this subject. However, there are some difficult issues in the process of research. Since the geometry configuration of natural phenomena is complex and the movement disciplinarian of it is abnormal, and it is too difficult to describe in the way of traditional Euclid Geometry. Snow, rain and cloud are three kinds of natural phenomena which can be seen anywhere in daily life, it is necessary in virtual environment. The simulation of three kinds of typical natural phenomena is studied in this paper.This paper first analyzes the characteristic of natural phenomena, the complexity of natural phenomena simulation which is decided by the characteristic of natural phenomena and talks about some common used methods of natural phenomena simulation. Particle system theory is further studied in this paper, with the characteristic of snowing; based on particle system model, the process of snowing is simulated. The method of applying pulverization to virtual environment is proposed to solve the problem of the blur of snowing environment and firn phenomena.Based on the snow particle model, with the characteristic of raining and the air dynamics, the process of raining is simulated in this paper. Water wave phenomena which is the rain drops into the water is studied, eight points water wave linear simulation arithmetic which is suit for real-time rending virtual environment is proposed by improving four points water wave arithmetic.This paper designs and realizes the volume cloud simulation arithmetic which is based on Perlin noise, and realized the simulation of cirrus, cumulus and stratus. Perlin noise is short of simulating cloud physical sports, so based on the CA theory cloud dynamic simulation arithmetic is designed and applied, the formation, extinction and movement of the blowing winds of cloud are realized, and extinction probability variables are introduced into the process of cloud extinction to solve the problem of cloud slow extinction and formation after extinction.更多还原