A New Approach for Creating a Spatial Adjacent Contour Tree

As one of the most fundamental elements of a topographic map, contour lines have a wide application. The relationships of contour lines play a key role in these applications. In this paper, a new approach of using tree structure to represent the relationship between contour lines is proposed. Firstly, contour lines in a contour map are divided into two types according to whether it is closed or not. Then create spatial adjacent contour trees for closed contour lines and open contour lines respectively. Finally, merge the two independent contour trees generating a complete adjacent contour tree, which represents the adjacent relationship of the contour lines. Besides, the inclusion relationship can be deduced from it with elevations. The algorithm is simple to understand and easy for realization of automation programs.