Comparison of Two Methods for Deriving Skeleton Lines of Terrain

Skeleton lines of terrain, i.e. ridge and valley lines are essential features on topographic maps. A skeleton line is the one with minimum slope among the slope lines. Slope lines are the lines of the steepest slope. Skeleton lines are used for a wide range of aims, e.g. emphasizing land forms, generation of high fidelity digital terrain models, terrain generalization, determining characteristic points of contours, etc. There are several methods for derivation of skeleton lines from contours and digital elevation models (DEMs). The primary objective of this study is to compare the results obtained by two different methods. Firstly, the skeleton lines are derived with respect to the algorithm developed by Aumann et al. (1991) using the contours generated from the height points of the DEM in addition to the characteristic points of the terrain. After that, the algorithm developed by Chang et al. (1998) for derivation of the skeleton lines from only the height points of the DEM is used. The results are compared with the skeleton lines of the terrain drawn by the operator in the stereo models of the area. For comparison, some cartographic and geomorphologic properties of contours and skeleton lines (i.e. numbers, locations and lengths of skeleton lines, and relationships between the contours and the skeleton lines) are used as the measurements. As a result, the skeleton lines derived from contours are more satisfactory than that are derived from DEM.