Research on Mountain Top Extraction Accuracy Based on DEM

Hilltops are one of the important terrain features. In view of defects of existing hilltop extraction algorithms based on DEMs, we establish a hilltop extraction model based on the maximum fluctuation threshold according to the terrain morphological feature of hilltops, followed by a relational analysis between different grid sizes of DEM and the accuracy in hilltop extraction with source data from a 1:50 000 DEM of the loess hills taken as an example. A hill top extraction was carried out for a Chinese inland area based on a DEM of 1:1 million; the amount and distribution of hilltops is discussed. The conclusion is: ① The hilltop extraction model based on the maximum fluctuation threshold has a very high application value because the extracted results of the hilltops accord to the actual relief quite well. ② For a terrain with a known generalization scale, there exists an optical DEM grid resolution; when the grid resolution of a DEM is not lower than this threshold, the extracted hilltops have a very good accuracy, otherwise, there would be uncertainty errors, not only in the amount of the extracted hilltops, but also in their spatial distribution. ③ There are a total of 40 038 hilltops in the Chinse inland study area with the altitude greater than 500m and the relative fluctuation greater than 200 m, according to the extraction results based on the DEM of 1:1 million.