Quantification of Airborne Lidar Accuracy in Coastal Dunes (Fire Island, New York)

To establish a basis for the utilization of lidar topography as a data source for coastal geomorphological analyses, this study generated statistical metrics of lidar error through the comparison of a June 2014 USGS collection of airborne lidar with a concurrently collected high-accuracy GPS topographical survey collected within the beach and dunes of a portion of Fire Island National Seashore. The examination of bare earth lidar error within the experiment site revealed a complex association between accuracy and environment within the coastal landscape. Accuracy was constrained to better than 50 cm RMSE in areas with vegetated dune topography and, overall, a 38.9 cm RMSE was measured. Higher accuracies were achieved in the flat, non-vegetated beach. A three-dimensional minimization of residuals between the lidar and GPS surveys reduced the total RMSE to 25.2 cm, indicating a correctable systematic offset between the surface generated from the lidar and the true ground surface.