| Researching Purpose of the dissertation:Simulation is a rising subject recently, along with the methods and application techniques of simulation researching deeply, with digital computer the simulation to practice system or imaginary system has been more and more recognized. Because a lot of high and new techniques have progressed, as net technique, graphics and image technique, multimedia, software engineering, information processing and auto-control etc., these has expedited the progressing step of simulation technique.With the application of visual system increasingly abroad, people demand the simulation fidelity higher of visual system, and long for the visual environment even more matching case nature, especially in flight, ship and car etc. simulation environments. The simulation degree of nature scenery will affect training effect directly, so to simulating the nature scenery is important in people's research.At present, the fact actuality of our army is that the pilot's training is called for to the best of its full and perfect, pilot must be provided with flexibility that can fly in various special instances, we emphasize using rate and self-contained rate, above all, these require pilot can disposition various special information. So it has very important reality signification to simulation the special weather in real time visual simulation of flight simulator.But as the restricting of computer and the running scrambling of rain and snow, so it is absolutely necessarily to simulation rain and snow effects in virtual condition. To simulating the snowing and raining can make pilots personally have on the scene feeling. Although we have very clear concepts to "snow" and "rain", but it is very difficult to define a well and truly definition for them. Snow and rain all have great random and scrambling, number is more, dynamic character is strong, and running hasn't any rule; so at all the time, it is one of challenging research directions in computer graphics that how to build a right model and generate reality applied snow and rain effects. In 1983, Reevs had put forward the particle system theory, it had provided a new method to simulate abnormity object. So far, the particle system has been considered that is the most successful image generation arithmetic to simulate the abnormity object. In particle system, we only concern the scene collectivity shape and diagnostic dynamic changing not each particle-self. The character of particle system makes it plenty embody the dynamic character and random character of abnormity object. In order to simulate the growth and death process of particles, each particle has a lifecycle that has a boring, growing and dying etc. courses.Researchers in the world have gone along attempted to simulate a lot of nature scenery by using particle system. They have simulated the branch, flow-cloud, skyrocket, spoondrift, smoke and haze etc. three dimensions complicated nature scenery well. There are some correlation reports about simulation snow and rain too. But the simulation results can only be used to generic animated scenes, it has some distance to meet real time requires of reality world, they are not real-time simulation in deed meaning.Particle system has lots of strongpoint, the large calculation is its most shortcoming, this shortcoming has a big antinomy with real-time require. The paper will research real-time visual scene simulation of flight simulator, there are many ground objects and the speed of fly is faster, so the generation and calling for the image must be real time, the calculation load of system without any special weather is bigger; if based on this system to add the special weather effect, it can not be meet the real time requires only simply using the particle system. How to solve this conflict? It is the discussion key of this paper that how to make the fidelity and real-time character reach all right in line.The solvent is that we design and innovate static and dynamic states attributes of particle based on the...
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