中文摘要：

公路三维表面模型是公路三维设计的基础，其关键是设计模型和地表模型的叠加运算。本文提出了一种基于TIN的地面模型和道路设计模型叠加算法，基本原理是把参考模型的边界多边形当作约束边界线插入操作模型，在保持参考模型拓扑关系不变的条件下对其进行局部LOP优化，然后删除位于参考模型边界线内的点和三角形。本文算法具有实现简单、速度快和运算稳定的特点，已成功应用在公路三维可视化设计中。

英文摘要：

Road surface model is basis of highway three dimension design, the key is the overlaid compute of design model and terrain model. This paper presents an overlaid algorithm of road design model （referred as reference model） and digital elevation model （named as operation model） which are based on triangular irregular network （TIN）. The principle of the algorithm is firstly extract the boundary of reference model and operation model, then insert boundary of reference model into operation model and thirdly optimize the operation model by Local Optimization Procedure （LOP） under the condition of keeping the topological relationship of reference model. The last step is to remove the triangles and terrain points which are fall into reference model. The advantage of the algorithm in this paper is simple, fast and steady.