数字高程模型(Digital Elevation Model,DEM)的数据误差和地形描述误差是两种不同性质的误差。本文以模拟实验获得的高精度DEM为数据源,分析坡度计算精度与DEM数据误差和地形描述误差的耦合关系。研究表明:DEM数据误差和地形描述误差对坡度精度影响是一个反向作用的过程。随着DEM格网的增大,数据误差的影响逐渐减小,地形描述误差的影响逐渐增大;在起伏变化地形区域,坡度误差先减小后增大,且存在一个最佳大小的格网,此时坡度误差最小。最佳格网的大小与DEM数据误差大小和地形起伏变化的复杂程度密切相关。研究结果表明,基于DEM提取坡度的误差来源与误差性质,对正确估算坡度精度具有很好的实际意义。
DEM data error is different from DEM' s terrain representation error. This paper focuses on the relation-ship among DEM data error, terrain representation error and slope accuracy based on high resolution and high accuracy DEM. The result shows that ( 1 ) data error reduces with the increase of the cell size, while terrain representation error rises rapidly ; (2) slope error firstly reduces and then increases. The lowest point of slope error' s trend is an important point. At this point, the corresponding cell size is the most suitable cell size of DEM. The cell size is not only related to the DEM data error, but also closely related to the terrain complexity. This paper makes them clear about the source and characteristics of slope error derived from DEM.