We have surveyed the slide from drone and ground by LiDAR and photogrammetry. The two datasets were co-registered (RTK GPS), allowing nominal precision and accuracy of <5 cm. One critical advantage of the LiDAR method is its ability to penetrate vegetation. This allows sampling points on soil, giving direct information on earth movements.

LiDAR

We used a LiDAR system based on the velodyne 16 puck Lite sensor (GeoSLAM Zeb Horizon), mounted on a Matrice 600 pro Unmanned Aerial Vehicle (UAV). Relative accuracy was validated using ground targets of a known size, as well as a handheld laser measurement unit compared to measurements taken fromthe point cloud.

Photogrammetry

Photogrammetry takes 3D geometric
measurements from photographs for recovering the precise positions of surface points. The output of photogrammetry is typically a map,
drawing, measurement, or a 3D model of some real-world object or scene. About 300 photos were collected with DJI’s Phantom 4 to generate the final 3D model.