TIN is able to do well in considering geomorphological feature, expediently and vividly figures discontinuous objects like cliffs, faulting, Valley coastline and complex topography. Through DTM based on TIN, we can easily know the terrain of any point within the region, obtain contour line, the section line, gradient map, and calculate height, regional area and volume of earthwork.The paper has analyzed the interpolation method of unknown elevation point in the DTM. The analysis of terrain data and the property of different DTM are mostly given. Study of Delaunay triangle grid theory and its generating method is given. Aiming at the property of triangle grid DTM, on the basis of Watson calculating method, the plot index, combing with the wing edge data structure and quick searching method designed by myself, is established, and the generating speed for restricting Delaunay triangle grid is improved efficiently. The midpoint added method is designed to solve the accordance problem of terrain property line and terrain object. The more vivid three-dimensional digital terrain model of Delaunay triangle grid is generated, and also applying technology of CAD, the application on the calculation of the volume of dump site for open-pit mine is given.Through the calculation of the volume of dump site for Jinduicheng wulfenite, this conclusion indicates that using the thesis model to calculate the earthwork is notonly convenient, fast, but accurate and reliable.
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