说明：  数字高程模型（Digital Elevation Model)，简称DEM，是通过有限的地形高程数据实现对地面地形的数字化模拟（即地形表面形态的数字化表达），它是用一组有序数值阵列形式表示地面高程的一种实体地面模型，是数字地形模型(Digital Terrain Model，简称DTM)的一个分支，其它各种地形特征值均可由此派生。
(Digital elevation model (DEM for short) is the digital simulation of the terrain (i.e. the digital expression of the terrain surface morphology) through the limited terrain elevation data. It is a real terrain model that represents the ground elevation in the form of a set of ordered numerical arrays. It is a digital terrain model A branch of DTM, from which all other terrain feature values can be derived.)