Research On VRT In 3D Visualization For Hydrogeological Structure Of WuDing River-WuLanMuLun River Groundwater System

Groundwater is a kind of water resources which is buried underground and can not seen directly. It is a pop problem between hydrogeology and computer science domain that how to reveal the invisible groundwater resources intuitively and realistically to people using modern scientific and technical method. At present, the research about 3D visualization technology applied in groundwater resources is matured overseas, but it is primary about this research at home. Therefore, a difficult duty that hydrologist faced is how to make good use of scientific visualization technology in groundwater science research.The study area of this thesis is the WuDing river-WuLanMuLun river groundwater system in the north of Ordos cretaceous basin. The aim is to virtually reveal the hydrogeological structure and groundwater flow by virtual reality technology. The 3D visualization model of hydrogeological structure in the WuDing river-WuLanMuLun river groundwater system is constructed. The application of virtual reality technology (VRT) is attempted in groundwater science field. This research belongs to the category of resolving actual problem by computer technology in the hydrogeology field essentially.On the basis of both collecting the geological and hydrogeological data and analysing the domestic and overseas study status in quo, the virtual reality technology was applied to visualize the hydrogeological structures of the WuDing river-WuLanMuLun river groundwater system directly and to open out the groundwater occurrence conditions and movement characters completely and exactly, and that provided a 3D visualization support for the evaluation and management of water resources in study area. The research is distinctive for the expression of groundwater spatial distribution characters in the virtual visualization model of hydrogeological stratum and the realization of the dynamic variety of groundwater in aquifers, which combines the movement of groundwater and aquifer and gives users visual experience directly and realistically.3D database is developed for managing basic data and editing the geologic structure model, ground water flow model. Microsoft SQL Server2000 is selected for manage system. The database include basic data database, graphics database and model database. Basic data database is support for building the 3D visualization model of hydrogeological structure in the WuDing river-WuLanMuLun river groundwater system. The basic database is used to store borehole data, water level data. Graphics database is used to store texture graphics and remote sensing data. Model database is used to store geologic structure model and groundwater flow model.There are two targets in this thesis: one is to virtually visualize the 3D visualization model of hydrogeological structure; the other is to virtually visualize the 3D visualization model of groundwater flow. VC++ programming language is used as developing tool, and OpenGL is used as visualization tool to virtually visualize hydrogeological structure model and groundwater flow model.Before constructing the 3D visualization model of hydrogeological structure, it's necessary to settle the borehole data of every stratum firstly and delete the conflict data. After the establishment of the rectangle grids combining all layers'losing boundary and boundary of study area, the Delaunay slice method of triangular net and kriging spatial interpolation technology are used to get TIN of every stratum in the geologic body according to geologic borehole investigation data. At the same time, some artificial interactive technologies were studied such as dividing section of geologic body, inquiring of the attribute table and moving in laneway and so on.On the basis of 3D visualization model of hydrogeological structure, the elevation on each scatter point of the stratum can be read after interpolation of each layer'boreholes using Kriging spatial interpolation technology. The Following is the display of the TIN of three stratum and the construction of the 3D geometry model of groundwater water table. Meanwhile, dynamic visualization of water flow model is realized by OpenGL. The contours and moving arrows are used to express the spatial distribution of groundwater and virtual visualization of the groundwater flow respectively. Users can arbitrarily slice the model, and also view the virtual flowing groundwater in the section of aquifers. In the end, the results of this research are summarized. The results are as follows:The DEM of every stratum and TIN of every water table were constructed according to the borehole investigation data and water level data considering Digital Elevation Model.Three-dimensional sense of the model was built by means of adding remote sensing images and textures.3D spatial distribution of hydrogeological stratum and groundwater flow is realized by virtual reality technology. The function of 3D interactive operation was enhanced, and the display of one or more layers of hydrogeological stratum was realized, functions of rotation, movement, zoom and arbitrary slice were realized; the spatial distribution and movement direction of groundwater is visualized by equal water table and flow lines, at the same time, groundwater flow can be shown dynamically.