Triangulated Irregular Network (tin) To Build And Application

As one of the "4D" products in spatial data infrastructure and the core database of GIS, digital elevation model (DEM) in mapping, remote sensing, agriculture, forestry planning, urban planning, civil engineering,geological analysis and other fields to have a wide range of applications. Digital elevation model has three representations that are regular square grid model, triangulated irregular network model and contour model , and TIN is the most basic and most important model, it can be described terrain surface at different levels of resolution, and can be flexible to handle special terrain. Thus, based on the DEM-based TIN construction, this paper discusses the structure of TIN-based digital elevation modeling principles and methods and the discrete points of the Delaunay Triangulation Algorithm for the establishment of a binding constraint triangulation, Finally, it analysis the establishment of TIN model in the application of earthwork calculations.In the course of this paper discusses, through the traditional method were compared and analyzed, the insertion point by point basis, put forward some new detail to improve the implementation method. Local optimized operations and improved Algorithm makes the construction of the large capacity of discrete points Triangulation faster and more efficient; on the embedded restrictions thus calculated to meet more realistic expectations of earthwork. Therefore, this thesis the main research and content as follows:1) when create discrete points of the delauney tribulation, the paper create convex and rectangular tolerance box, a virtual grid , The original grid of discrete points of a block adaptive and index relations. When located the triangle that contains the point,it make use of the fast point location algorithm,simple empty circucircle and the circle test the formula. these improvements make the Delaunay triangulation mesh is more efficient.2) Constrained Delaunay triangulation based on the theory of light scatter domain subdivision above method, the two-step algorithm has been improved based on the completion of construction of constrained Delaunay triangulation. Application in the process of mathematical tools such as vector dot product to improve the calculation of the rough spots to judge, to continue to use the fast indexand most quickly positioning method, and the line tangent to the constraints and other special cases were dealt with, to further improve the algorithm robustness.3) For the triangular structure constrained on the basis of the TIN model is applied, the text of the TIN model Earthwork calculations analyzed the advantages of accuracy, the final combination of a golf course project in Dongguan City, gives an example.