Oblique view of Barter Island bluffs

Example of a high-oblique photograph taken with an unmanned aerial system (UAS), or drone, of the coastal bluffs of Barter Island on North Slope of Alaska. The photographs from different time periods can be compared, using a technique called structure-from-motion photogrammetry, to measure changes in the coastal bluffs. This area of Alaska is experiencing very high rates of coastal erosion; note where the bluff has collapsed onto the beach and covered USGS ATV tracks, made just 24 hours earlier.