Research On Some Techniques Of Contour Lines' Recognition And Extraction

As is well known, automatic recognition of geographic maps is one of the important research projects in GIS. And as the crucial element reflecting topographical structures, contour lines have always been the key unit in such projects. Presently, some developments have been made about their extraction from map, but how to handle their interruption and automated capture of the heights of open contours are still not settled thoroughly. In this paper, we mainly deal with these problems.Taking brown plate map as data source, we carefully analyze the main reason making contours' long-distance break and the relationship between contours known height and unknown, then propose a layering-based breakpoints connecting method, and present a new contours evaluation method based on reasoning from the edge of map as wellAt firstly, the research and development situation of the contours recognition are summarized, the significances of this paper are also discussed. Secondly, several known methods about recognition of geographic maps are introduced. Some of them will be used in latter section. Thirdly, on the base of preprocessing scanned map, we separate each kind of map elements from brown map. By this step, we make preparations for breakpoint connecting and automated labeling open contours. Then, after discussing previous methods dealing these two problems, the detailed approach about layering-based breakpoints connecting method and automated labeling open contours are describe. Experiments show the correctness and feasibility of our method. Finally the author gives some conclusion and comments on these two methods and the prospects of the development of contour lines recognition.