The Research Of Undersea Terrain Visualization Based On Direct3D Technology

With the use of marine resources, the development of information technology and the popularity of terrain visualization, the seafloor relief visualization research has become a hot issue. Development and utilization of marine energy is an effective way for human to maintain their own human development and expand the living space. However, the marine environment is unknown and varied and the seabed is complicated and abstract, so the research of digital seafloor relief visualization is a hot and difficult in recent years.In this paper, Visual Studio is taken as a platform. The view-dependent LOD quadtree algorithm is used to interpolate and construct triangular grid based on Direct3D technology of three-dimensional graphics library. The true three-dimensional seafloor relief is rendered by calling the function of the graph library. The use of HLSL shading language can set light and add texture, thereby generate more realistic three-dimensional environment. In addition,because GPU (Graphics Processing Unit) has good parallel processing capabilities, it can share the workload of the CPU. It also can improve computing speed and rendering effect.In this paper, the experimental data of seafloor relief is used to build DEM modeling,analyzes the common problems of seafloor DEM generation and introduces the data preprocessing methods of coordinate transformation, edge matching and interpolation thinning. Finally, the seabed regular grid DEM is generated. In the method of drawing the terrain, LOD quadtree algorithm is used to build seafloor relief modeling and the real-time dynamic continuous grid is structured. The constructive process and crack elimination method of the LOD data structure is elaborated. HLSL shading language is used to render and the different levels of detail effect is realized by changing viewpoint.Based on the key technology of Direct3D, the program of three-dimensional terrain is written, debugged and run in the Visual Studio development environment. The use of HLSL shading language can set light, add texture and render environment, so the rendered terrain is more realistic. By using HLSL language, the difficulty of GPU programming is reduced, a variety of constraints need to be considered when writing specific code is gradually disappearing, and more unified way of programming brings convenience for the seabed topography programming. At the same time, the effects of topographic maps are made more gorgeous and colorful. On the one hand, the application of Direct3D technology and OpenGL technology are compared in processing performance; on the other hand, the rendered effects of using Direct3D separately and using Direct3D together with HLSL are also compared,which demonstrates the advantages and significance of this method in the 3D seafloor relief visualization.In this paper, visualization system constructed can not only truly display three dimensional seafloor relief,but also can switch the grid model and rendering mode,and the smallest details of rendering the value is adjusted to achieve the seabed terrain roaming.Finally,three-dimensional seafloor relief visualization system is achieved with real-time roaming and human-computer interaction function.