| Digital watershed,as the frontier research field of water conservancy information,provides the basis for the planning and management of social economic macro decision of the watershed and plays an important role in promoting the watershed management modernization and developing water industry.In this paper,the 3D digital watershed platform was developed based on GIS and virtual reality technology.The digital watershed framework and flow visualization method,such as scalar field visualization,vector field visualization,water simulation technique and combined condition drawing,was studied and implemented.The application of professional application model and digital simulation platform in navigation management and flood control system is implemented.The main work and research results are as follows:(1)The general framework for the development of the 3D digital watershed platform is proposed,and the technical route for modeling and storing the 3D spatial data of the digital watershed is studied.On the basis of OSG(3D graphics engine)and osgEarth(visualization tool),the model of virtual terrain and building of the 3D digital watershed platform was established with the use of the LOD dynamic paging mechanism and the fast modeling method for spatial data.The visualization module was developed to load and render a large-scale watershed model data,in order to optimize the display performance of the platform.(2)The flow data was obtained based on the simulation of hydrodynamic model.Through the application of GPU shader programming and graphics rendering pipeline,the flow visualizations,such as water depth contour surface,LIC,IBFV and Arrow fields,were implemented.The RTT(render to texture)technology was applied to accelerate the speed of the GPU extraction of flow data flow with the use of the data preprocessing,the texture buffer object binding and the viewport clipping.By using the method of normal texture mapping and wave function transformation,the virtual flow effects of rivers and seas were simulated,of which flow velocity distributions were displayed.The interface with flow visualizations was integrated with the platform in order to optimize the display effect of flow model.(3)The application of navigation management and flood control was developed and integrated with the platform.In the application of navigation management(from Jiangjin to Chongqing),the functions of the waterway information query and display,the real-time monitoring and flow simulation,and the ship dynamic information query and display were implemented and integrated through the methods of monitoring,storage,calculation and display.The system provides more intuitive and rich waterway and real-time flow information for ship navigation,which effectively improve the rate of waterway navigation efficiency and safety.In the flood simulation of Harbin dike project,based on triangulation terrain mesh topology,the left and right triangle search method was applied to simulate active flood submerged.The functions of inundation simulation and inundation control scheme demonstration were implemented in this system,which provides a support tool for flood control. |
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