三维数字地形图是用三维离散点表示地物和地貌的空间位置和立体形状。它是基于抽象符号的三维空间数据显示和可视化表达，对客观世界的表达更完整准确，它以立体造型技术向用户展现地理空间现象，不仅能够表达空间对象间的平面关系，而且能描述和表达地面的高程和地物的高度，提高了数字地图的空间认知能力和空间分析能力。通过研究数字地面模型（DTM）的原理知识,分析已开发数字高程模型（DEM）建立的有关软件，进一步讨论研究其在工程领域的应用推广，并以杨家岭开发区的场地平整以及煤炭露天开采的实例，论证三维数字地形图的在土方量计算、表面积计算、露天矿坑剥离量计算等方面的应用功能和精度误差对比分析。得出三维数字地形图在工程应用中应采取合理计算模型的方法结论。

3D digital topographic maps use 3D discrete points to express the spatial location and three-dimensional shape of the surface features and landscapes. It is the demonstration and visual expression of three-dimensional spatial data based on the abstract symbols, which expresses the objective world more completely and accurately. It applied 3D modeling techniques to show the users geospatial phenomenon, which can not only express the plane relations between spatial objects, but also can describe the ground elevation and terrain height, and enhance spatial cognition and spatial analysis capability of the digital map. This paper studies the principle of the digital terrain model (DTM),and analyzes developed created DEM related software, further discusses the study in engineering applications and promotion, then takes field leveling and open-pit mining of coal in Yangjialing Development Zone for examples to demonstrate the application functionality and precision error comparative analysis of 3D digital terrain map in the earthwork volume calculations, the surface area calculation, the open pit stripping calculation, and other aspects, the conclusion is: reasonable computational model should be applied in three-dimensional digital topographic maps during engineering applications.