The U.S. Geological Survey (USGS) Remote Sensing Coastal Change (RSCC) project collects aerial imagery along coastal swaths, in response to storm events, with optimized endlap/sidelap and precise position information to create high-resolution orthomosaics, three dimensional (3D) point clouds, and digital elevation/surface models (DEMs/DSMs) using Structure-from-Motion (SfM) photogrammetry methods. These products are valuable for measuring topographic and landscape change, and for understanding coastal vulnerability and response to disturbance events.
A nadir (vertical) aerial imagery survey was conducted from Cape Lookout, North Carolina to the Virginia-North Carolina border on August 30th and September 2nd, 2019, to document pre-storm conditions in preparation for the passing of Hurricane Dorian. The observations along the coastline cover an approximately 275-kilometer-long by 300 to 700-meter-wide swath of coastline and encompass both highly developed towns as well as natural, undeveloped areas, including the federal lands of Cape Lookout National Seashore and Cape Hatteras National Seashore. Low altitude (300 meters above ground level) digital aerial imagery were acquired from a manned, fixed-wing aircraft using a Sony A7R 36 Megapixel digital camera, along with precise aircraft navigation Global Navigation Satellite System (GNSS) data. Data were collected in shore-parallel lines, flying at approximately 50 meters per second and capturing true color imagery at 1 Hertz, resulting in image footprints with approximately 75-80% endlap, 60-70% sidelap, and a ground sample distance (GSD) of 5.3 centimeters. The precise time of each image capture (flash event) was recorded, and the corresponding aircraft position was computed in post-processing from the aircraft navigation GNSS data; precise image positions can then be determined by accounting for the lever arm offsets between the aircraft GNSS antenna and the camera lens. Position data, provided as latitude/longitude/ellipsoid height, is referenced to the North American Datum of 1983 (NAD83(2011)).