Digital Elevation Model Reconstruction of a Glaciarized Basin Using Land-Based Structure from Motion

In a climate change context, volume variations of glaciers can be efficiently evaluated by comparison of Digital Elevation Models (DEM) of the ice surface, taken at different time frames. However, traditional methods of DEM reconstruction lack either in resolution or they are costly, considering the remoteness of certain basins. This study aims for testing a method called Structure from Motion (SfM) for high resolution DEM reconstruction on a 2.7 km glaciarized basin in the Aqqutikitsoq mountain range, Western Greenland. The SfM method is capable to recreate the 3D structure of an object using a set of highly overlapping pictures covering the entire surface of the object itself. This concept is applied to the Aqqutikitsoq glacier, which was mapped using a consumer grade camera in August 2014. The 3D model was obtained by processing with the software Agisoft Photoscan 249 pictures taken from four main viewpoints. The georeferencing was done using 50 Ground Control Points (GCPs) acquired during the ground survey. The GPS coordinates of the GCPs were obtained using a Post Processing Kinematic (PPK) method, which reaches centimeter precision. The results show that the glacier surface is mapped with a resolution of 0.79 m and a elevation accuracy of 0.73 m. Considering the level of the equipment involved, the high resolution achieved, the logistic and technical ease of the method, it can be stated that SfM represents a powerful and efficient technology for DEM reconstruction suitable for glaciers located in remote areas.