Experiences of UAS photogrammetric rockslide monitoring in the alpine terrain in High Tatras, Slovakia

The development of surveying methods and equipment has moved from conventional surveying methods to modern technologies such as Unmanned Aerial Systems (UAS) aerial photogrammetry or Terrestrial Laser Scanning (TLS). These methods were used to monitor the rockslide of the Tatranská magistrála hiking trail in the High Tatras, where a rockslide occurred as a result of its washing away. This research is devoted to a detailed comparison of the results obtained using different measurement methods based on the minimum distance of point clouds. During the research, TLS technology, UAS photogrammetry using DJI Phantom 4 RTK UAS and DJI Matrice 30T UAS were used, and freely available data from Airborne Laser Scanning (ALS) was also downloaded for comparison. The rockslide in the area of the hiking trail occurred by 2.32 m, which is confirmed by the method based on determining the minimum distance of points.