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The late 1950s, DEM began to be adopted by a great deal of concern, in surveying, civil engineering, geology, mining engineering, landscape architecture, design of roads, flood control, agriculture, planning, military engineering, aircraft and battlefield simulation The field has been widely used. The DEM theory and technical areas related to the techniques and methods of data collection, data structure design and processing, the model interpolation algorithm and algorithm, DEM 3D visualization technology, DEM precision evaluation of its quality development level of control, and computer technology. It has long been said that the DEM the accuracy of the terrain, data acquisition, gross error detection, quality control, data compression, visualization, and application of DEM and triangulated irregular network TIN establish interpolation technology with continuously research. With the rapid development of computing technology and the wide application of DEM, looking for fast modeling, interpolated high-precision, high degree of visual modeling method is necessary. The DEM can use a mathematical function of one or more of the terrain, said this mathematical function is often referred to as the interpolation function. When the DEM surface modeling, model any point elevation information can be obtained from the DEM surface, this is very similar to the surface geometry modeling. DEM surface modeling can be regarded as the curved shape of the terrain surface. It is precisely because of the above reasons, we can construct the free-form surface method applied to the DEM surface modeling, also can be used to build a cross-section of the terrain model line free curve constructed Act. Modeling of terrain surface model and its cross-section diagram generated, the main contents are as follows: 1, at home and abroad on the terrain surface modeling Research on the significance of the terrain surface modeling research. 2, the existing rule-based Grid (GRID) and triangulated irregular network (TriangulatedIrregular Network-TIN) are two data formats terrain modeling method, summed up the performance and characteristics of three-dimensional terrain surface modeling. 3, due to the data collected outside the industry often discrete point data, you must first build a triangulated irregular network after interpolation regular grid data. Therefore, the paper in-depth study triangulated irregular network configuration network, TIN configuration network has been improved, and VB programming, in order to improve its efficiency. Of several commonly used DEM interpolation method and accuracy interpolation Scope computation comparative analysis. 5, free curve and surface construction methods and the theory of three-dimensional data field visualization study summarizes the advantages and the nature of the B-spline basis functions. 6, free curve construction method for the quasi-uniform B-spline method used in a cross-sectional view of the terrain model generation, and the tunnel cross-section measurement of roughness analysis and evaluation. 7, based on the quasi-uniform B-spline constructor method of curves and surfaces in the MATLAB programming environment for a group of regular grid data three-dimensional terrain surface modeling and its visualization.
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