Low-altitude aerial imagery collected from a Helikite at the Pea Island National Wildlife Refuge DUNEX Site, North Carolina in September and October 2021

These JPEG images were collected every second with a camera (either a Ricoh GRII HD or PT SONY) labeled 'aa##', where an 'r' indicates a Ricoh camera and 'pt' indicates the SONY camera, and the following 2 digits normally indicate the camera ID or last digits of the serial number. The camera was then hung from the Helikite so that the camera faces downward. The Helikite was on a 40-50 m string attached to a kitesurfing harness then walked down the beach in a pattern to get overlapping imagery of the entire field site. It is recommended when using the imagery for photogrammetric purposes to also use the ground control points (GCPs) (see larger work citation).

The images acquired with the camera were geotagged and processed to add additional information required by the USGS to the EXIF headers using ExifTools (https://exiftool.org/, version: 12.06) and the files were renamed to a unique identifier using Namexif (http://www.digicamsoft.com/softnamexif.html, version 2.1) to avoid any possibility of duplicate names. These steps are described here. 1. No GNSS navigation data was available with the photos, but relatively accurate (~1 m) estimates of camera locations were calculated in Metashape. These locations are provided for each survey in the file 2021029FA_PINWR_photoLocations.csv and includes Latitude, Longitude, and Ellipsoid height in NAD83(2011) and Easting, Northing, and Orthometric height in UTM18N NAVD88 (m). These can be loaded into photogrammetry software to assist in alignment processing. 2. Keywords were added to each image with the following command in the directory with all the photographs: exiftool -sep ", " -iptc:keywords="DUNEX, PINWR, North Carolina, 2021-029-FA, USGS, aerial imagery" *.JPG 3. Additional EXIF information (image description, artist, contact, credit, and copyright) was added in the directory with all the photos with the command: exiftool -csv=directory\name\EXIF_tags.csv *.JPG To read out the photo information to a csv when in the directory with the photos the command is: exiftool -csv *.JPG > directory/name/allheaders_out.csv For more information on tags see https://exiftool.org/TagNames/EXIF.html. 4. All the JPEG images were renamed with Namexif (https://namexif.en.uptodown.com/ v 2.2 accessed April 2020) to ensure unique filenames and compliance with the USGS Coastal and Marine Hazards and Resources Program's best practices for image naming convention. Images were renamed with a field survey ID prefix; a flight number and ID that distinguishes among USGS cameras by make, model, and camera number; the image acquisition date and coordinated universal time (UTC) in ISO8601 format, and a suffix with the original image name. For example, image name '2021029FA_f01r02_20210907T165822Z_M1050226.JPG', 2021029FA is the survey ID, f01 is the flight number, r02 is the internal camera ID, 20210907 is the UTC date in the format YYYYMMDD. A 'T' is used to separate UTC date from UTC time in format HHMMSS followed by a Z, and M1050226.JPG is the original raw photo name appended to the end of the new filename. If the camera time was collected in EST, the time in Namexif was shifted +4:00:00 to be in UTC.