Low-altitude aerial imagery collected from a Helikite at Head of the Meadow Beach, Truro during field activity 2021-014-FA on February 4, 2021

These JPG images were collected with a camera (Ricoh GRII HD) labeled 'r##', where 'r' indicates a Ricoh camera, and the following 2 digits normally indicate the camera ID. The camera was wired to the GNSS receiver and duct taped together, then hung from the Helikite (2021014FA_Truro_HelikiteCameraAttachment_browse.JPG) so that the camera faced downward. The Helikite was on a 50 m string and kitesurfing harness; together the Helikite and gear were walked down the beach. The horizontal positions and elevations of each image (2021014FA_Truro_f1_photolocations.csv) were recorded from the GNSS receiver (EMLID Reach M2), which were processed in PPK mode using the MASS CORS network. The navigation data was added to the image EXIF information after the flight as described in the process steps. It is recommended when using the imagery for photogrammetric purposes to also use the Aeropoint locations (see larger work citation Navigation: 2021014FA_Truro_nav_AeroPoints.csv) as ground control points.

The GNSS navigation data was processed in Inertial Explorer (https://novatel.com/products/waypoint-software/inertial-explorer, version 8.70.8722). In the software, the data were processed using an 'Antenna Height' of 0.0 m to indicate that there was no offset from the GPS to the camera. The positions were processed in the NAD83(2011) datum, providing the Latitude, Longitude, and H_Ell_m attributes and then Geoid 12B was applied using NAVD88 as the vertical datum and UTM Zone 19N for the horizontal coordinate reference system to produce the Northing, Easting, and H_Ortho_m attributes. All of the attributes here are provided in the 2021014FA_Truro_f1_photolocations.csv but only the latitude, longitude, and H_Ortho_m (NAVD88) were embedded in the image header.

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. Using the GNSS navigation from the previous step, ExifTools was used to geotag each photo with the GPSDateStamp, GPSTimeStamp, GPSLatitude, GPSLongitude, and GPSAltitude stored in a csv file with the command:' -geotag "C:\directory\name\Geotags.csv" -geosync=+23 C:\directory\name\of\photos' where the -geosync command tells the exiftools that the GPS and photo time are offset by 23 seconds. The TimeStamp is in UTC, the latitude and longitude geotags are in NAD83(2011), and the altitude geotag is the H_Ortho_m in NAVD88 (m). The first row of the CSV are the headers; the first column is SourceName (unique image names), and the rest of the columns are the geotags listed in Step 1. Keywords were added with the following command in the directory with all the photographs: exiftool -sep ", " -iptc:keywords="Head of the Meadow Beach, Massachusetts, 2021-014-FA, Ricoh, USGS, aerial imagery" *.JPG 2. Additional EXIF information was added in the directory with all the photos with the command: exiftool -csv=directory\name\EXIF_tags.csv *.JPG Where the CSV file has the attributes below as headings. To read out the photo information to a csv when in the direcotry with the photos the command is: exiftool -csv -f -filename -GPSDateStamp -GPSTimeStamp -GPSLongitude -GPSLatitude -n -Artist -Contact -Comment -Credit -Copyright -ImageDescription -OriginalFileName -AttributionURL -Event -GPSAreaInformation -GPSMapDatum *.JPG > directory/name/out.csv Tags may be added or removed to the command above depending on the information desired.
3. All the JPG images were renamed with Namexif 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 the field survey ID prefix; flight number, and ID that distinguishes USGS cameras by make/camera number, the image acquisition date, coordinated universal time (UTC) in ISO8601 format, and a suffix with the original image name. For example, image name '2021014FA_f01r02_20200306T165822Z_M1040356.JPG', 2021014FA is the survey ID, f01 is the flight number, r02 is the internal camera ID, and 20200306 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 M1040356.JPG is the original raw photo name appended to the end of the new filename. Because GPS data was collected in UTC and had a 23 second offset from the time produced by the camera (EST), the time in Namexif was shifted +4:00:23.

Update the publication date to 'go live' date. Modified browse graphic name to be the URL to the browse graphic. This work done on 20220307. Add PID to metadata (20220411). Any edits to the metadata also include an update to the metadata date.