A case study on terrestrial SfM photogrammetry slope change detection without stable ground control points

Butcher B.; Walton G.; Kromer R.; Gonzales E. · 56th U.S. Rock Mechanics/Geomechanics Symposium (2022)

Resumen

Daily remote monitoring of slope processes using terrestrial structure from motion (SfM) photogrammetry is a relatively new technique in engineering geology. In this study, a five-camera photogrammetry monitoring station was installed in the Siguas River Valley near Majes, Peru in December 2020 for long-term monitoring and study of slope processes. The study area includes a retrogressive rockslide-debris slide with areas of rockfall sourced from the head scarp, areas of water-driven erosion, and other related geomorphological processes ranging from 100 to 900 m away from the camera stations. Challenges with photo and point cloud alignment accuracy and, ultimately, change detection accuracy arise due to the constant ground movement and lack of suitable locations for ground control point (GCP) installation. In this paper, we investigate point cloud alignment methods for the purpose of change detection at sites where the distance from the photogrammetry station to the area of interest is variable and where there are no stable GCPs. Additionally, we present preliminary change detection results in relation to landslide movement rates at the site. For the tested methods that produced reasonable results, the average rate of movement for the rockslide-debris slide was estimated to be between 3 and 35 cm per month, on average.

Instituciones: Universidad Nacional de San Agustín de Arequipa