Orthomosaic representing Marconi Beach, Wellfleet from images acquired during field activity 2021-022-FA on March 17, 2021

Digital Surface Model was created in Agisoft Metashape v. 1.7.2 using the following general steps (see Over and others, 2021): 1. Project created and imagery (located in larger work citation 2021022FA_Marconi_f1.zip) and position (located in larger work citation 2021022FA_Marconi_f1_photolocations.csv) data were brought in using the NAD83(2011) datum. 2. Photos were aligned at high accuracy (the pixels are not subsampled for increased processing speed) with a keypoint limit of 40,000 and unlimited tie points. Alignment uses the positions and matching pixels between images to create point clouds and put the imagery into a relative spatial context. Photos that failed to align/find tie points contained breaking waves and water, but are kept in the project to reconstruct the orthomosaic because they are still spatially orientated even if they do not contribute to the elevation model. Metashape software refined and optimized the camera positions and lens model in a least squares sense to minimize the reprojection error or the distance between the measured points and the software created points. 3. Nine ground control points (GCPs) (2021022FA_Marconi_nav_AeroPoints.csv located in the larger work citation were added to the project in NAD83(2011) and manually placed on the images as markers. 4. A dense point cloud was generated using high quality (images are not subsampled) and a low frequency filtering algorithm. Accuracies for the GCPs were set 0.01 m and accuracies for the camera positions were set to 5 cm, resulting in a total camera position error of 0.05 m and a total GCP error of 0.016 m. The dense point cloud was then edited to remove noise by filtering by point confidence before generating an interpolated digital elevation model (the software calls all models elevation models, but technically it is a surface model because it includes vegetation/canopy returns, a terrain model would be only bare earth returns). 5. The digital surface model was used to build an orthomosaic, which was then exported from the software at a resolution of 25 cm and in NAD83(2011)/UTM Zone 19N (ESPG:6348) and GEOID 18B NAVD88 in meters.