提出了一种新的自动提取山脊线和山谷线的方法－方向剖面法。该方法可以根据穿过高程数据点的各个方向的剖面线特征，自动识别DEM中可能的山脊点和山谷点；然后，用修正的Hilditch细线化算法筛选山脊点和山谷点；接着再把筛选后两两相邻的山脊点或山谷点连接起来，形成山脊线或山谷线的“雏形”；最后，将山脊线或山谷线“雏形”中封闭的三角形断开，并剔除过短的山脊线和山谷线。用真实DEM数据进行试验研究，其自动提取的山脊线和山谷线与高程等值线图反映的地形起伏基本一致，从而证明了该方法的有效性。

In this paper, a new method for automatic extraction of ridge and valley axes from DEM, named as Directional Profile Approach(DPA), is proposed. DPA can automatically determine whether a grid point in DEM is a possible ridge(or valley) grid point, according to the features of the profiles through this grid point. Applying this new method to extracting ridge and valley axes automatically from DEM, the following several procedures must be accomplished: First, the all elevation grid points which may be located in ridge and valley lines are automatically recognized with DPA. Then the modified Hilditch thinning algorithm is applied to selecting the ridge and valley grid points recognized by DPA. Third, the every two neighboring ridge points or valley points are connected and rudimentary form of the ridge or valley axes is constructed. Finally, the closed triangles in ridge and valley axes are broken and the short branches are removed. A real DEM was used for testing data, the ridge and valley axes extracted automatically by this method can basically represent the topographic features of the corresponding topographical map. Therefore, this new method is effective.