Surface currents retrieved from airborne video

Within this paper we describe a methodology to retrieve ocean surface currents from video data of ocean surface waves. The video sequences were acquired at nadir by an off the shelf quadcopter in the range of visible light. The quadcopter is equipped with an actively controlled gimbal for stabilization of the video camera and records all the information needed to geocode the video data. The geocoded video sequences are used to measure surface wave properties such as wave direction, length and phase velocity. These properties enable to measure the surface current, which results from the difference of the observed phase velocity to that given by the linear dispersion relation of surface waves. The method was applied to video data collected over the Elbe River in vicinity of a weir, showing the overall applicability.