A Study On Three-Dimensional Visualization Of Hydrological And Topographic Data Of Changjiang Estuary

A variety and numerous of spatial-temporal hydrological environmental data such as water depth, salinity, turbidity, tidal current have been obtained and measured in field over past years at Yangtze estuarine area. For the nature and complex of diversity source, instruction, type, dimension on in-stiu data, it is absent and insufficient to visualize the geographic distribution, interaction and relation among these data at surface and under water level with one or two dimension expressions way. In this paper, we construct hydrological scenario and three dimensions visualize platform for displaying, expressing, analyzing and simulating past, current and future hydrological and environmental data, in conjunction with GIS, visualize technology and 3D modeling. The content of this paper including:(1) The construction of underwater relief model. Fractional Brownian motion (fBm) model was used to compute fractal parameters of underwater terrain and the interpolation algorithm combining with the random midpoint displacement method was implemented to construct 3D underwater relief by Matlab toolkit package. The result show that:it has preferable detail and precision on terrain's complexity and irregularity using fBm model. With Fledermaus visualization software, the real show of underwater relief was realize with the texture layer of remote sensing image by adjusting color scheme and Fledermaus parameters, such as terrain shadow, view point, luminance and transparency.(2) The establishment of hydrological environmental models and Yangtze Estuary environmental scenario visualization. With GIS, Matlab,3ds Max and Fledermaus software, we integrally development a real and interactive Yangtze Estuary environmental scenario simulation system to construct sediment concentration model, salinity model, sediment type model and typical features model and to display spatial distribution of sediment, salinity vertically distribution, the type sediments and surface features at the mouth of Yangtze River.(3) The study of accretion and erosion at typical shoals and tidal area at the mouth of Yangtze area. We select Guyuansha shoal, Chongming Dongtan, Hengsha shoal, Jiuduansha and Nanhui bank as case study area. With the accretion and erosion model developed by Fledermaus package, topographic evolution and isobaths distribution at Yangtze Estuary was analyzed and deposition rates were calculated during the period from 1990 to 2004.