Research Of TIN Construction

With the rapid development of GIS technology and the application, high requirements of DEM data in quality are needed. As a form of the DEM data, TIN data has advantages on expression of ground and the earth's surface in different hierarchy and space. However, TIN is a complex data structure, and it also has complexity in use and management .In addition, the speed is especially slow with the prodigious data. The development of TIN is limited on a certain extent. Therefore, These problem such as mending the TIN model, improving its precise and the fidelity of terrain description ,and enhance in the TIN constructing efficiency ,are become hotspots in the TIN study.The paper, firstly analyzed construction of currently routine TIN, summarized deficiencies, and brought forward the method of constructing TIN with outside available line and inside terrain structure line. The available line was automatically picked-up and the Raster data was interpolated from the scatter elevation points. And then terrain structure line was distilled from the pretreated Raster data by studying plane curvature and slope-shaped combination, and the fidelity of terrain description is ensured. Finally, based on the convex hull technology, the construction of the TIN data with more precision and fidelity is carried out by programming, which made good use of the internal and external constraints.The main content and work can be summarized as follows:1. The commonly methods of TIN construction was analyzed and their advantages and disadvantages were discussed .Finally, the improved algorithm of rapidly constructing TIN, which based on Convex Hull was built up.2. The boundary of factual and effective discrete elevation data points is studied and the algorithm about the effective boundary extraction is optimized and carried out. In addition, in the process of extraction, the problems about omission of the peripheral points and the connection and interaction of scope lines in the complex area are resolved, and the issue of unreal boundary existing in the conventional boundary is also effectively mended.3. The methods of distilling the terrain structure line from Raster data were analyzed and their strengths and weaknesses were summed up. Finally, combined the plane curvature with slope-shaped, the structure line was successfully distilled .And through setting the parameters to adjust its width; the structure line was more in line with the actual landform.4. Based on Convex Hull Technology and integration of internal and external constraints, the experimental system was designed and realized for TIN construction by Arcobjects and Visual C + +6.0 development environment, in which simulated and several groups of real terrain data were implemented, the data precise is analyzed, and ultimately tested to validate the feasibility and validity of the idea in this paper.