Abstract: While converting DEM into contours, the existing methods are incapable to find a good balance between curve smoothness and the loss of topographic accuracy. Thus, the authors thought of the method of converting DEM into contours based on slope division filtering. This method uses different-sized windows to average filter the slope division and control the filtering elevation difference, which better balances the curve smoothness and the loss of topographic accuracy and meanwhile automatically recognizes, interrupts and deletes the narrow intermediate contours between the index contours. The authors made use of the ArcGIS+Python script to develop a tool which could automatically convert DEM into contours. The tool was applied in contours collecting in the program of Digital Guangxi Geo Spatial Framework Construction and had got good results.

Key words: DEM, contours, slope division, filtering, accuracy control