Detecting Glacier Surface Motion by Optical Flow

In this study, we assessed the feasibility of using optical flow, in particular, large displacement optical flow (LDOF) method as a possible solution to obtain surface movement data to derive ice flow velocities in a glacier. Tests were carried out at the Viedma Glacier, located at the South Patagonia Icefield, Argentina, where terrestrial monoscopic image sequences were acquired by a calibrated camera from April 2014 until April 2016. As for preprocessing, the Correlated Analysis method was implemented to avoid and minimize errors due to the measurable changes in lighting, shadows, clouds, and snow. The results show a flow field with a maximum surface velocity value of 3.5 m/d. The errors were minimized by averaging the image sequence results based on seasons, in which the Total Error Reconstruction yielded fairly good mean accuracy (0.36 m/d). In summary, it was demonstrated that LDOF can provide accurate and robust solution to detect daily changes in the glacier surface.