Monitoring alpine glaciers from close-range to satellite sensors

In this paper the use of different types of remote-sensing techniques for monitoring topographic changes of Alpine glaciers is presented and discussed. Close range photogrammetry based on Structure-from-Motion approach is adopted to process images recorded from ground-based and drone-based stations in order to output dense point clouds. These are then directly compared to detect local changes by mean of M3C2 algorithm, while digital elevation models are interpolated to find global ice thinning and retreat. Medium-resolution satellite imagery can be exploited to monitor the glacier evolution at lower resolution but including the development and collapse of large crevasses. A case study concerning the Forni Glacier in the Raethian Alps (Italy) is presented to demonstrate the feasibility of the proposed approach by adopting data sets collected from 2016 to 2018.