Research On Dynamic Mapping Method Of Flow Field Based On Particle System

In recent years, with the constant development of the computer technology,RS technology, spatial information collection technology, GIS technology and virtual reality technology, map has gradually evolved from paper map to electronic map. At the same time, the way of the presentation of the spatial information has experienced significant change, from two-dimension to three-dimension, from static state to dynamic state. And there appears new means of spatial information presentation, such as animation map and particle system. The traditional static visualization method can not express the dynamic characteristics of time-varying visualization with visualization and vividness.Particle system is addressed in computer graphics to achieve the simulation presentation of some fuzzy, abstract and irregular-shaped natural phenomenon and geographical process. The application of the particle system for simulation of the abstract natural phenomenon has become a hot pot. As a kind of fuzzy natural phenomenon, flow field is one perfect expression of the particle system.According to the particle characteristics of the flow field, the paper studies dynamic mapping method in different scales by dynamic simulation and presentation of marine flow field with the observation of the constant movements of a mass of random particles. First, based on the full conclusions and comparisons among the previous achievements on the flow field visualization,the paper analyzes their advantages and disadvantages respectively, designs the dynamic symbol of the flow field particles system, studies the static and dynamic visual variables of the particle symbols and proposes the main visual variable which influences the particle symbol. Then the paper applies the LOD technology to partition the flow field data and establishes multiscale presentation model of particle system by analyzing the feature and the structure of flow field data. It presents a linear gradient method which increases the density of the particles gradually in the grid, studies the step length of the particles under different scales with the application of the map load method and achieve the multiscale presentation of the flow field particle system. Finally, the paper achieves the dynamic mapping effect of the particle system based on WorldWind 3D visualization platform and evaluate the mapping effect by questionnaire. The particle system in the paper works well in visualization presentation of the flow field. This provides new method for marine flow field visualization.