利用DEM提取山顶点精度研究

山顶点是重要的地形特征点之一,针对现有的基于DEM的山顶点提取算法存在的缺陷,本文首先依据山顶点的地表形态特征,建立了基于最大起伏度阈值的山顶点提取模型;然后,以黄土丘陵1:5万不同格网属性DEM为基础,分析了DEM格网属性对山顶点提取精度的影响特征;最后,基于1:100万DEM提取了中国内陆山顶点数量及分布情况。研究结果表明:① 基于最大起伏度阈值的山顶点提取模型提取的山顶点符合实际地形意义,具有很好的应用价值。② 对于已知综合尺度的地形,存在最佳DEM格网分辨率阈值,当实际DEM格网分辨率不低于该阈值时,提取的山顶点具有很好精度,否则提取的山顶点数量及空间位置均存在不确定性偏差;③ 在我国的1:100万DEM中,中国内陆满足海拔高度500 m以上、相对起伏大于200 m的山顶点共有40 038个。

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.