Research On Simulation Technology Of Polluted Airflow Emission In Virtual Scene

With the rapid development of the socialist industrialization, the byproduct of the manufacturing process, such as exhaust air, becomes an irritating problem. The visualization of the pollution proliferation will make for the scientific management and environmental protection departments to provide an intuitive analytic method. However, establishing an acceptable scene of pollution diffuse process concerns a number of difficulties. Simulation of three-dimensional terrain is the first step to build a virtual scene. Then, air pollution-proliferation can be simulated in the scene. According to the designated complex scene, the requirement of the real-time performance and realistic rendering are both needed to be taken into serious consideration. To meet the user's immersion in the sense of scene, this system is also required to be optimized to achieve the roaming function. Based on careful analysis and summary of previous work, research achievements, which have been done in this paper, can be briefly stated as follow:Firstly, this paper carefully examines the method for bitmap-based access to the terrain elevation and building three-dimensional terrain, which makes it more convenient for the scientists to acquire and modify terrain data. As for the neglected features of the designated geographic area, this paper adopts Diamond-Square algorithm in fractal technology to fuse grid points, so as to enhance the performance of constructed mountain in a virtual scene and make it more accordant to the natural features of the objective terrain.Secondly, Gaussian diffusion formula is employed in this paper in order to describe density filed of continuous diffusion sources in upper air. Then, based on particle system, this paper also emulates the movement of the polluted gas. Because of the drawbacks within the conventional methods which use the fixed size particles to plot the virtual smoke movement, this paper proposes a whole new method that alters the size, color and transparency of the particles as their location changes in the density field to achieve brilliant performance of smoke effect and lower the numbers of used particles as well. Thirdly, this paper adopts OpenGL display lists, double-buffering technology to enhance real-time rendering of scenes, and adopts Billboard technology to increase three-dimensional effects of the particle group; In addition, the particle system for smoke by drawing has the limit issue of space, in accordance with hydrokinetics equations this article builds the model of pollutant dispersion and improves the way proposed by Jos Stam to simulate two-dimensional smoke. It achieves the simulation of visual pollutant dispersion in a wide region.Forthly, by means of a topographic scene, this paper proposes a roaming system using a key board as interactive input device. In this paper, real-time scheduling scene, the level of detail model, elimination of hidden surface and cutting process, were studied for the requirements of large-scale roaming in the system performance.