Objectives  Traditional remote sensing methods are often limited by the complex terrain and the hardware equipment, which often leads to in-situ measurements that cannot comprehensively, accurately and quickly obtain the slope rock structure data sets. Unmanned aerial vehicle (UAV) oblique photogrammetry technology can obtain comprehensive information on rock structure.

  Methods  We describe a method for acquiring, visualizing, and extracting three-dimensional information of high slope rock structure based on the dense surface points. The oblique photogrammetric data acquired with UAV is considered and a multi-rotor drone with single-lens is used for aerial surveys to reconstruct the three-dimensional point cloud model of the high slope. The Hough normal algorithm and the HSV(hue, saturation, value) algorithm are used to build a visual three-dimensional rock mass structure model and the model is spherical k-means clustering to complete the automatic extraction of rock structure.

  Results  From the three-dimensional rock structure analysis, it is possible to quickly extract rock structure characteristics such as orientation, spacing and trace length by rendering the geometry of the three-dimensional slope face.

  Conclusions  Further research is being carried out in order to build blocky slope masses and identify the kinematic instability of the high limestone cliffs.