基于航空影像的高陡边坡突岩识别方法

Identification of Rocky Ledge on Steep and High Slopes Based on Aerial Photogrammetry

高陡边坡上的突岩容易在自重、地震、开挖卸荷等作用下失稳,威胁到水利工程的安全.因此,对突岩进行早期调查具有重要意义,但由于水利枢纽区域面积较大,交通不便,人工调查耗时且危险.本文提出了一种基于航空影像的高陡边坡突岩快速识别方法.该方法主要包括3个步骤:(1)通过无人机摄影测量生成边坡点云模型;(2)使用核密度估计方法(KDE)对点云模型的赤平投影结果进行统计分析,以将点云模型分割成平滑区域和非平滑区域;(3)用一种基于密度且对噪声鲁棒的空间聚类算法(DBSCAN)对非平滑区域的点进行聚类,以识别代表突岩的点簇.该方法可以从整个边坡识别多个突岩,有效减少人工工作量,将该方法应用到两河口水电站某自然边坡的突岩识别中,可较为方便地得到岩体的边界和几何要素,为下一步稳定分析提供基本数据.

The rocky ledge on steep,high slopes is easy to lose stability under the action of gravity,earthquake,excavation and unloading,etc.,which threatens the safety of water conservancy projects.Therefore,the early investigation of rocky ledge is of great significance.However,due to the large slope area and inconvenient traffic,the manual identification is time-consuming and dangerous.A rapid identification method for the rock ledge based on unmanned aerial vehicle(UAV)photogrammetry is proposed in this paper.This method consists of three steps:(1)Generate the point cloud model by UAV photogrammetry;(2)segment the slopes into smooth areas and non-smooth areas by kernel density estimation(KDE)of the point’s normal vector,clustering the points of non-smooth areas by the density-based spatial clustering of applications with noise(DBSCAN);(3)classify the point clusters representing rocky ledge by the geometric feature.The method can identify possible rocky ledge from the whole slope,which reduces the artificial workload.The proposed method has been successfully applied to the slopes near Lianghekou hydropower station to obtain boundaries and geometric features of rocky ledges which will provide basic data for the future stability analysis.