| River network and related watershed information directly derived from DEM, is the basis of development and application of distributed hydrological models. Author has researched the technique of the automated extraction of the information of hydrology from digital elevation models(DEM) in recent years detaily,and discussed the principles and methods of the automated extraction of the characteristics of topography from DEM. Based on our study of the ext ract ion techniques using DEM in recent years, we find that the key to their successful application lies in two factors. The first is how to adequately define topographicst ructure morphol- ogically or hydrologically, and the second is how to design algorithms for the defined topographic structure. From the improving the approachs of the filling depressions and making gradient of plain in DEM, the extraction efficiency and result accuracy are better than existing methods and better fit to deal with the mass data of DEM.The main contents on visualization of this paper involve the opening figure base of OpenGL and the technique of Java3D and so on. And we have achieved three dimensional modeling on the base of TIN from the data of DEM. We also have achieved the three dimensional render and visualization superposing the the characteristics of topography from DEM.A suit of software was developed based on D8 processing method, of which functions included identifying and processing sunk areas in DEM, automatically generating river network and dividing watersheds, and 3D visualization of the derided feature information overlay on DEM topography data. The Yanqi River watershed in Beijing was selected as research area, and the test result of generating river network showed that the improvement on the depression and plat area algorithm was effective, the derived features were consistent with the actual case on the whole, and the operation efficiency was improved greatly. That made thesimulation of hydrology features more actual significance. |
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