3D visualization of spatial surface hydrological process:a case study at Huangtuling watershed in Zhejiang province

Spatial hydrological process involves the 3D geospatial and a temporal dimension.The visualization of it is helpful to understand it more correctly and more efficiently.In this paper an approach representing spatial hydrological process dynamically and interactively is developed,using Huangtuling watershed in Zhejiang province as a case area.Our research development involves the following major phases: 1) creation of ground spatial reference,2) 3D display of spatial hydrological process and 3) dynamic and interactive display.In the PC environment,OpenGL functions are called through Visual C++ to realize the dynamic 3D display.OpenGL functions are powerful in 3D modeling and rendering and therefore suitable for presentation of the spatial hydrological process,while the technology of double buffers ensures the continuous display of the temporal changes of spatial hydrological process.The main aspects of the approach such as surface modeling,terrain coloring,normal computation in lighting,water transparency handling,temporal hydrological data processing and interaction parameters inputting,are discussed in details. The system can display realistically the 3D dynamic changes of water continuum at different surface elevations,and the navigation and synchronized animation play important parts in observing,analyzing and comparing spatial hydrological process.