Photogrammetric Techniques for the Determination of Spatio-temporal Velocity Fields at Glaciar San Rafael, Chile

Abstract

Glaciar San Rafael in the Northern Patagonia Icefield, with a length of 46 km and an ice area of 722 km2, is the lowest latitude tidewater outlet glacier in the world and one of the fastest and most productive glaciers in southern South America in terms of iceberg flux. Spatio-temporal velocity fields in the region of the glacier front were determined from monoscopic terrestrial image sequences recorded by an inter-vallometer mode high-resolution digital camera over several days. In these image sequences, a large number of glacier surface points were tracked by subpixel accuracy feature tracking techniques. Scaling and georeferencing of the trajectories obtained from image space tracking was performed using a multi-station GPS-supported photogrammetric network. The technique allows for tracking hundreds of glacier surface points at a measurement accuracy in the order of one decimeter, for typical glacier movement rates, and an almost arbitrarily high temporal resolution. The results show velocities of up to 16 meters per day.