The base data of the quantitative analysis about land feature and the automatic drawing of topographic map is furnished by Digital Terrain Model(DTM),it is the basics of Geography information System(GIS).

• 数字地面模型为多种地形特征的定量分析与地形图的自动化绘制提供了基本数据，它是建立土建CAD和地理信息系统的基础。