The Grid-based DEM'S Automatic Extraction Of Contour Lines

Most current topographic information is based on the new grid in the form of acquisition, access and storage, so that the contour lines from the GRID algorithm to high-level expression has become more important. Grid-based DEM contour extraction from the project has been in my department has been applied.Based on the regular grid based on the extracted contour designed and implemented by the diagonal grid points on the contour interpolation algorithm and contour output data in three-dimensional terrain model is used to insert the contour lines to make up both their lack of topographic expression.Focus on the content and features:1. the concept of contour lines, classification and characteristics of a simple exposition. Contour map discussed in military applications, illustrates the contour map of the important applications in the real position. Reading and use of contour lines as the basic description of the way the military commanders of military topographic map is essential.2. briefly discusses the digital elevation model (DEM) of the origin, concept and application, DEM mainly Grid and TIN TIN GRID two forms. Meanwhile, according to the respective contour lines and DEM characteristics, to compare the expression of both the merits of the terrain, shows, in real applications, according to different purposes, we need to use different expressions, respectively.3. discusses the grid from the rules of the basic contour extraction algorithm ideas, divided into first, and then interpolated edge tracking and tracing edge interpolation two. In the process of striking contour tracking methods traverse many, the algorithm focuses on the more limited scope and traverse the data structure used by the program's efficiency. Analyzed and discussed several key cross-grid solution to the problem of ambiguity.4. from the programming point of view on two grid-based DEM contour extraction algorithm, the implementation process, different data storage structure and the efficiency of different algorithms were compared, can be designed to reduce the search grid collection strategies to improve system efficiency, the result is stored in a searchable grid list collection efficiency than the array storage; first interpolation is better than edge tracking algorithm then interpolated edge tracking algorithm; have to pay a substantial increase in the grid system of separation algorithm efficiency contour lines in the track when a number of advantages become more pronounced.5. designed and implemented a three-dimensional contour DEM model with integrated display, from the perspective of visual topography make the expression of these two methods is inadequate and has regular grid DEM based on the contour algorithm provides a powerful algorithm to evaluate the means.