顾及约束的网络道路三维模型简化方法

蒲浩^{1, 2}，李伟^{1, 2}，赵海峰^{1, 2}，宋占峰^{1, 2}

(1. 中南大学 土木工程学院，湖南 长沙，410075；2. 高速铁路建造技术国家工程实验室，湖南 长沙，410075)

摘 要：针对道路三维模型数据呈海量，且包含大量约束边界的特点，提出顾及约束的网络道路三维模型简化方法。在服务器端已建立道路三维整体模型的基础上，首先提出顾及约束的半边折叠误差度量方法；然后，在服务器端采用半边折叠操作对初始道路模型进行整体简化，同时建立操作层次树；最后，建立远程视相关模型重构准则，在操作层次树上确定需传输至客户端的视相关结点数据，并结合约束边优先策略，在客户端实现道路三维模型的快速视相关重构。研究结果表明：该方法简化率高，远程动态浏览时保留必要的约束边界，需要传输的数据量小，满足道路远程实时交互式可视化要求。

关键词：道路工程；网络三维可视化；三维模型简化；误差度量；视相关重构

Web-based road 3D model simplification method considering constraints

PU Hao^{1, 2}, LI Wei^{1, 2}, ZHAO Haifeng^{1, 2}, SONG Zhanfeng^{1, 2}

(1. School of Civil Engineering, Central South University, Changsha 410075, China;2. National Engineering Laboratory for High Speed Railway Construction, Changsha 410075, China)

Abstract:Based on the fact that the road 3D model has massive data and a large number of constraints, a web-based road 3D model simplification method considering constraints was put forward. The road 3D integrated model was built on the server beforehand. First, a half-edge collapse error metric that considered a large number of road constrained edges was proposed. Then, original road model was integrated simplified on the server by half-edge collapse, and meanwhile operating hierarchical tree was built. Finally, remote view-dependent reconstruction criteria were established. According to these criteria, minimum nodes data that needed to be transferred to client were quickly selected in the operating hierarchical tree. Combined with constrained edges priority strategy, road 3D model quickly view-dependent reconstruction was realized on client. The results show that high simplification rate can be obtained, the necessary constrained edges can be retained, small scale of data transmitted through network is needed in the process of remote dynamic browsing, and the requirements of road remote real-time interactive visualization are met.

Key words:road engineering; web 3D visualization; 3D model simplification; error metric; view-dependent reconstruction