PHOTOGRAMMETRIC MONITORING OF GRAVITATIONAL MASS MOVEMENTS IN ALPINE REGIONS BY MARKERLESS 3D MOTION CAPTURE

Gravitational mass movements represent a significant hazard potential in Alpine regions. Due to climate change and an associated increases in extreme weather events, this risk is growing. For a better predictability of such events and the monitoring of affected areas, a precise determination of the ongoing movements is necessary. In this paper, a method for monitoring of Alpine slope movements based on image sequences is presented. By means of SIFT features, corresponding key points in the images of different epochs are found. Then, using forward section, the object coordinates of the points are computed. By using these coordinates and the detected correspondences, three-dimensional motion vectors can be determined. The calculated vectors are checked for significance based on their accuracy. The vectors found have a high spatial density compared to manually marked points and are detected automatically. In order to detect even small-scale movements, they are determined with an accuracy of a few millimeters. The data basis is a sequence of images of an active landslide on the Hochvogel mountain (Alps, Germany) which were taken in 2018 and 2021. On average, the calculated motion vectors show a movement of 75 mm.