Method for automatically extracting terrain characteristic line according to vector contour line data

The invention discloses a method for automatically extracting a terrain characteristic line according to vector contour line data. The method for automatically extracting the terrain characteristic line according to the vector contour line data comprises the following steps of: determining characteristic points of terrain; classifying the characteristic points to obtain ridge points and valley points; determining judgment factors for generating a ridge line and a valley line; and automatically generating the ridge line and the valley line. The characteristic points of the terrain such as the ridge points and the valley points are determined by using the characteristics of curved lines of a vector contour line and a geometrical morphology analysis method, and then connected to form the terrain characteristic line such as the ridge line and the valley line. The method is high in identification speed, the extracted terrain characteristic line such as the ridge line and the valley line is in accordance with actual terrain change, and errors caused by manual extraction can be effectively eliminated. The method can be used for extracting a terrain contour line from digital terrain data. Furthermore, the method is convenient to operate, simple, and great in practical application value.