基于数字表面模型的岩体结构面产状获取

针对传统现场接触式测量获取岩体结构面参数效率低、工作量大、结果精确性受人为因素影响等问题，本文结合数字摄影测量技术与运动法（structure from motion，SFM）进行岩体三维数字表面模型重建，并在此基础上建立了岩体结构面自动识别方法。岩体数字表面模型重建步骤主要为岩体影像资料采集，基于尺度不变特征变换（Scale-Invariant Feature Transform，SIFT）算法进行图像特征匹配、稀疏点云构建、点云稠密化以及岩体曲面模型重构。结构面识别方法流程主要为:首先平滑岩体数字表面模型；通过改变搜索半径和角度阈值实现模型平面分割；基于区域生长原理进行结构面搜索；最后基于随机采样一致性拟合结构面得到结构面产状。将该方法应用于甘肃北山地下实验巷道，实现了巷道三维数字表面模型的重建与结构面产状数据获取，最后将识别到的结构面分组表征在模型表面。与人工实地测量方法以及现有的结构面识别软件相比，本文提出的方法具有良好的准确性，可为工程应用提供一定的参考。

Extraction of the discontinuity orientation from a digital surface model

The traditional field contact measurement for obtaining parameters of the rock mass discontinuity is of low efficiency and big workload,and the accuracy of the results are affected by human factors.In this paper a method is presented to automatically recognize the discontinuity based on the three dimensional(3D)digital surface model(DSM)of rock mass obtained with the digital photogrammetry and structure from motion(SFM)algorithm.The steps of rock mass DSM reconstruction include collecting rock mass images,matching image features based on the Scale-Invariant Feature Transform(SIFT)algorithm,reconstructing sparse point cloud,encrypting point cloud,and reconstructing the rock mass surface model.The main flow of the discontinuity recognition method include smoothing the DSM of rock mass,changing the searching radius and the angle threshold to split model plane,searching the discontinuity based on the regional growth principle,and fitting the discontinuity based on random sampling consistency to get the orientation.The method is applied to the underground experimental roadway in the Beishan area of Gansu,and the reconstruction of 3D digital surface model of roadway and the orientation acquisition of discontinuities are realized.The discontinuities are also mapped on the roadway model by groups.A comparison the results with those of the manual field measurement method and the existing discontinuity recognition software shows that the method proposed in this paper is of good accuracy and can provide a certain reference for engineering applications.