The accurate expression of terrain morphology is the essence of the urban terrain model construction. As the skeleton of urban terrain, urban road has special geometric and semantic characteristics. The road is a strip-shaped feature, which is flat in the horizontal direction and gently undulating in the vertical direction, and the roads are interlinked and connected. This research takes Jianye District of Nanjing as the studied area to explore the digital elevation model (DEM) construction method of urban roads. Firstly, the 1:1000 digital topographic map(DTM) is used to extract the point, line and plane elements of urban roads. Secondly, a selection method of elevation points for urban road DEM (UR-DEM) construction is proposed, referring to the urban road engineering design specification. That’s the improved Douglas–Peucker (D–P) algorithm with elevation change rate. Thirdly, the bidirectional interpolation method is constructed to keep the directional characteristics and geometric features of the urban roads. Then, the intersection processing method based on semantic connectivity is used, so that the roads can be connected correctly. Finally, UR-DEM is generated by inverse distance weighting (IDW) interpolation model, and the construction results are also analyzed and evaluated in this paper. The experimental results show that: (1) the existence of abnormal elevation points seriously affects the geometric shape of urban road, and the removing abnormal elevation points method proposed in this paper can maintain gently undulating characteristics of road well and largely reduce the road jitter. (2) The UR-DEM construction method proposed in this paper can express the spatial geometric and semantic features of urban road well, the model accuracy is higher than that of classical methods and the RMSE is 0.0225 m. This study can provide reference for the DEM construction of other urban features, and can provide data support for the process simulation of urban surface confluence and urban construction planning.

地形形态的准确表达是城市地形模型构建的关键。作为城市地形的骨架，城市道路具有特殊的几何和语义特征。道路是条形特征，在水平方向上是平坦的，而在垂直方向上是平缓起伏的，道路是相互连接的。本研究以南京市建业区为研究区域，探讨了城市道路数字高程模型的构建方法。首先，使用1：1000数字地形图（DTM）提取城市道路的点，线和平面元素。其次，参考城市道路工程设计规范，提出了城市道路DEM（UR-DEM）施工高程点的选择方法。这是具有高程变化率的改进的Douglas–Peucker（DP）算法。第三，构建双向插值方法以保持城市道路的方向特征和几何特征。然后，采用基于语义连通性的交叉口处理方法，使道路能够正确连接。最后，通过逆距离加权（IDW）插值模型生成UR-DEM，并对施工结果进行分析和评估。实验结果表明：（1）异常高程点的存在严重影响城市道路的几何形状，本文提出的消除异常高程点的方法可以很好地保持道路的平稳起伏特性，并大大降低了道路的抖动。（2）本文提出的UR-DEM构造方法能够很好地表达城市道路的空间几何和语义特征，模型精度高于经典方法，RMSE为0.0225 m。该研究可以为其他城市特征的DEM建设提供参考，也可以为城市地表汇流和城市建设规划过程模拟提供数据支持。