Study And Realization On The Algorithm About Simulation Of Snow Scene Based On Temperature Change And Particle System

The simulation of natural phenomena has always been one of the most challenging problems. The simulation of snow in the natural landscape could greatly enhance the realistic effect of the virtual scene. The irregular shape of snowflakes, the uncertain movement and the regularity of snow by the environmental factors determined that its modeling approach and the description of its movement was more difficult. The simulation of snow was becoming a hot issue in dynamic modeling of irregular objects. Particle system presented by Reeves was an effective way for the simulation of snow. In the meanwhile the influence of the temperature in natural environment could not be ignored in the simulation process. Therefore, this paper focused on the following areas.Firstly, this paper analyzed the existing natural-photorealistic rendering theory, algorithms and the scope of their application. The development of particle system and its basic principles and models was analyzed. Especially, we studied on the characteristics of snow and the key issues about snow-related simulation including the shape of snowflakes, the whereabouts campaign of snowflake, the effect of the wind and the visual effects of snow scene and so on.Secondly, this paper analyzed the existing literature on the influence of environmental temperature and the size and density of the snowfall. Using the temperature changes to control the size and density of snowflakes was presented. The empirical formula between the temperature and the size of snowflake was popularized. The temperature and snow density equation was formed. The goal was focused on the simulation of the actual snow scence. An algorithm called SST (Simulation of Snowflake based on Temperature) achieved by controlling the temperature to product snow was presented. When snow had come into being, we simulated a realistic falling snow scene according to the snow falling movement. Thirdly, the improvement of the snow accumulation prediction algorithm simulation method was achieved after immiting the idea which we mentioned before about the temperature and the density of the snow.The improved algorithm omitted the process that each triangular patche must launch some particles of snowflakes to the sky in original algorithm. It greatly simplified the complexity of the simulation algorithm, which could shorten the time for drawing snow scenes, and achieved quick simulation of snow.Finally, a snow-simulation system was designed and achieved. The algorithm presented in this paper was tested by the system.