Multispectral aerial imagery collected during uncrewed aircraft systems (UAS) operations: Plum Island Estuary and Parker River NWR (PIEPR), Massachusetts, November 14, 2017 and March 28, 2019

Step 1: Set up equipment.
A MicaSense RedEdge multispectral camera was mounted on a 3DR Solo Quadcopter UAS. The MicaSense RedEdge acquires images at 1.2 megapixels with image dimensions of 1280 X 960 pixels in 12-bit DNG format. The lens focal length is 5.5 mm, and the camera has global shutters for all five bands (blue, green, red, red edge, and near infrared) with an aperture of f2.8. File sizes are generally 1.8 MB on disc. The camera is generally down-looking, so the imaged area was dependent on the tilt of the quadcopter during flight. For flight, the camera was set to record images at 2-second intervals, activated before takeoff and deactivated after landing.
A 3DR GPS module and MicaSense Downwelling Light Sensor were connected to the camera with 6-pin cables and secured on top of the aircraft with velcro. The camera received power from a connection to the UAS. The 3DR GPS module was a pre-configured u-blox NEO-7 that used a 25 x 25 x 4 mm ceramic patch antenna with a 5 Hz update rate. It recorded telemetry information including latitude, longitude, altitude, dilution of precision, date and time, roll, pitch, and yaw. The downwelling light sensor measured ambient light for each of the five spectral bands captured by the camera. For each camera shutter trigger, it recorded spectral data including spectral irradiance, roll, pitch, yaw, gain, and exposure time. Data from the downwelling light sensor and GPS module were automatically incorporated into the metadata embedded in the header of each image.

Step 2: Collected images.
The images were collected during field activity 2017-057-FA on November 14, 2017, and field activity 2019-009-FA on March 28, 2019. During each field activity, flights were flown approximately 80 meters above ground level along pre-planned lines and lasted the duration of the UAS battery life (approximately 15 minutes) or until the flight was completed or aborted. During a flight, five images were captured every 2 seconds, one for each of the five wavelengths (blue [475 nm], green [560 nm], red [668 nm], red edge [717 nm], and near infrared [840 nm]). The ending number of the image filenames corresponds to the band number: _1 corresponds to blue, _2 corresponds to green, _3 corresponds to red, _4 corresponds to near infrared, and _5 corresponds to red edge. After a flight, the SD card was removed from the camera, and all files related to the flight were downloaded and organized by flight number.
At the start of the field activity and throughout the day, calibration images were taken of a MicaSense Calibrated Reflectance Panel by manually triggering the camera shutter with the UAS held over the panel. Before the images can be used to create photogrammetry products, they need to be radiometrically calibrated to account for changing light conditions during flight. The standardized reflectance values provided by MicaSense for this panel are 0.61 for near infrared, 0.63 for blue, and 0.64 for green, red, and red edge. Calibration images should be chosen to temporally match the UAS images as closely as possible.

Step 3: Renamed the 2019 images and incorporated survey information into the 2019 images' metadata.
A Python script (image_RenameTagFilter.py) was run to rename the 2019 images and incorporate standard USGS tags and additional survey information into the 2019 images using ExifTool by Phil Harvey. The images were renamed to append the field activity ID, camera ID, flight ID, and UTC date and time to the beginning of each filename. For example, IMG_0003_1.tif was renamed to 2019009FA_m01f01_20190328T155433Z_IMG_0003_1.tif where 2019009FA refers to the field activity, m01 refers to the camera (MicaSense sensor 1), f01 refers to the flight number, 20190328T155433Z refers to the image date and time in the ISO 8601 standard (YYYYMMDD T [time separator] HHMMSS Z [Zulu/UTC time]), and IMG_0003_1 refers to the original filename assigned to the image by the camera.
The Python script also incorporated standard USGS tags into the metadata embedded in the header of each image using ExifTool. Images may have different metadata formats embedded in their headers, and the script incorporated survey information into the following three image metadata formats: Exchangeable image file format (Exif), International Press Telecommunications Council (IPTC), and Extensible Metadata Platform (XMP). The standard USGS tags at the time have since changed and were subsequently updated in a process step below. The following tags were populated and were not subsequently updated because they are no longer part of the standard USGS tags. Please note that the Exif UserComment tag was populated for all the 2019 images, while the remaining IPTC and XMP tags were only populated in the calibration images collected at the start of the 2019 survey and in the images collected during flight 6.
Exif tag and the information used to populate the tag (for all 2019 images):
UserComment (for calibration images): Flight CAL UserComment (for images collected during flights): Flight [ID] ; target altitude 80 m
IPTC tags and the information used to populate the tags (for 2019 calibration and flight 6 images):
Caption-Abstract: One band of a multispectral image from a low-altitude aerial survey in Plum Island, MA. Captured with a MicaSense RedEdge at a target altitude of 80 m. WHCMSC field activity number 2019-009-FA (https://cmgds.marine.usgs.gov/fan_info.php?fa=2019-009-FA). CopyrightNotice: Public Domain. Please credit U.S. Geological Survey Keywords: Plum Island, MA, Massachusetts, 2019-009-FA, UAS, nadir, multispectral, USGS
XMP tag and the information used to populate the tag (for 2019 calibration and flight 6 images):
Caption: One band of a multispectral image from a low-altitude aerial survey in Plum Island, MA. Captured with a MicaSense RedEdge at a target altitude of 80 m. WHCMSC field activity number 2019-009-FA (https://cmgds.marine.usgs.gov/fan_info.php?fa=2019-009-FA).

Step 4: Renamed the 2017 images.
The images collected during the 2017 survey were renamed to append the field activity ID, camera ID, flight ID, and UTC date and time to the beginning of each filename. The MicaSense camera recorded the GPS date and time from the GPS connected to the camera to the Exif CreateDate tag. Before renaming the images, the Exif CreateDate tag was copied to the Exif GPSDateStamp and GPSTimeStamp tags using the following ExifTool (version 11.86) command:
exiftool -P "-GPSTimeStamp<CreateDate" "-GPSDateStamp<CreateDate" -overwrite_original *.tif
To rename the images, a command was run on each flight's images to extract the GPS date and time using ExifTool and format them into the new filename. For example, the following command was used on the images collected during flight 2:
exiftool -csv *.tif -GPSTimeStamp -GPSDateStamp | awk -F, '{split($1,a,"_"); split($2,t,":"); split($3,d,":");print "mv -v "$1" 2017057FA_m01f02_"d[1]d[2]d[3]"T"t[1]t[2]t[3]"Z_"$1}' | sh
An example renamed filename for the 2017 images is 2017057FA_m01f02_20171114T155121Z_IMG_0015_1.tif where 2017057FA refers to the field activity, m01 refers to the camera (MicaSense sensor 1), f02 refers to the flight number, 20171114T155121Z refers to the image date and time in the ISO 8601 standard (YYYYMMDD T [time separator] HHMMSS Z [Zulu/UTC time]), and IMG_0015_1 refers to the original filename assigned to the image by the camera.

Step 5: Incorporated survey information into the images' metadata.
The updated standard USGS tags were incorporated into the metadata embedded in the header of each image using several commands. As previously mentioned, the MicaSense camera recorded the GPS date and time from the GPS connected to the camera to the Exif CreateDate tag. First, the Exif CreateDate tag was copied to the Exif GPSDateStamp and GPSTimeStamp tags for the 2019 images using the following ExifTool (version 11.86) command:
exiftool -P "-GPSTimeStamp<CreateDate" "-GPSDateStamp<CreateDate" -overwrite_original *.tif
Next, the following ExifTool command was run to incorporate standard USGS tags and survey information into the metadata embedded in the headers of the 2017 images:
exiftool -P "-XMP:PreservedFileName<Filename" -IPTC:Credit="U.S. Geological Survey" -IPTC:Contact="WHSC_data_contact@usgs.gov" -EXIF:Copyright="Public Domain" -XMP:UsageTerms="Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty." -EXIF:ImageDescription="https://cmgds.marine.usgs.gov/fan_info.php?fan=2017-057-FA; One band of a multispectral image from a low-altitude aerial survey in Plum Island, Massachusetts, from USGS field activity 2017-057-FA" -XMP:AttributionURL="https://doi.org/10.5066/P9PP35F4" -EXIF:GPSAreaInformation="position derived from UAS GPS" -EXIF:GPSMapDatum="EPSG:7660 (WGS 84 [G1150])" -EXIF:Artist="Woods Hole Coastal and Marine Science Center (WHCMSC) Aerial Imaging and Mapping (AIM) Group" -overwrite_original -ext tif .
Then, the following ExifTool command was run to incorporate standard USGS tags and survey information into the metadata embedded in the headers of the 2019 images:
exiftool -P "-XMP:PreservedFileName<Filename" -IPTC:Credit="U.S. Geological Survey" -IPTC:Contact="WHSC_data_contact@usgs.gov" -EXIF:Copyright="Public Domain" -XMP:UsageTerms="Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty." -EXIF:ImageDescription="https://cmgds.marine.usgs.gov/fan_info.php?fan=2019-009-FA; One band of a multispectral image from a low-altitude aerial survey in Plum Island, Massachusetts, from USGS field activity 2019-009-FA" -XMP:AttributionURL="https://doi.org/10.5066/P9PP35F4" -EXIF:GPSAreaInformation="position derived from UAS GPS" -EXIF:GPSMapDatum="EPSG:7660 (WGS 84 [G1150])" -EXIF:Artist="Woods Hole Coastal and Marine Science Center (WHCMSC) Aerial Imaging and Mapping (AIM) Group" -overwrite_original -ext tif .
Finally, the following ExifTool command was run on both the 2017 and 2019 images to duplicate values from Exif and IPTC metadata tags to XMP tags because various software packages read different tags:
exiftool -P "-XMP-photoshop:Credit<IPTC:Credit" "-XMP-iptcCore:CreatorWorkEmail<IPTC:Contact" "-XMP-dc:Rights<EXIF:Copyright" "-XMP-dc:Description<EXIF:ImageDescription" "-XMP-exif:all<GPS:all" "-XMP-exif:GPSLatitude<Composite:GPSLatitude" "-XMP-exif:GPSLongitude<Composite:GPSLongitude" "-XMP-exif:GPSDateTime<Composite:GPSDateTime" "-XMP-photoshop:DateCreated<EXIF:DateTimeOriginal" "-XMP-xmp:ModifyDate<EXIF:ModifyDate" "-XMP-dc:Creator<EXIF:Artist" "-XMP-tiff:Make<EXIF:Make" "-XMP-tiff:Model<EXIF:Model" -overwrite_original .
The following metadata tags were populated in the image headers using the above ExifTool commands. Please note that only a subset of these tags may be accessed depending on the software used to view the image metadata.
Exif tags and the information used to populate these tags:
Artist: Woods Hole Coastal and Marine Science Center (WHCMSC) Aerial Imaging and Mapping (AIM) Group Copyright: Public Domain GPSAreaInformation: position derived from UAS GPS GPSDateStamp (2019 images): duplicated from Exif CreateDate GPSMapDatum: EPSG:7660 (WGS 84 [G1150]) GPSTimeStamp (2019 images): duplicated from Exif CreateDate ImageDescription (2017 images): https://cmgds.marine.usgs.gov/fan_info.php?fan=2017-057-FA; One band of a multispectral image from a low-altitude aerial survey in Plum Island, Massachusetts, from USGS field activity 2017-057-FA ImageDescription (2019 images): https://cmgds.marine.usgs.gov/fan_info.php?fan=2019-009-FA; One band of a multispectral image from a low-altitude aerial survey in Plum Island, Massachusetts, from USGS field activity 2019-009-FA
IPTC tags and the information used to populate these tags:
Contact: WHSC_data_contact@usgs.gov Credit: U.S. Geological Survey
XMP tags and the information used to populate these tags:
AttributionURL: https://doi.org/10.5066/P9PP35F4 Creator: duplicated from Exif Artist CreatorWorkEmail: duplicated from IPTC Contact Credit: duplicated from IPTC Credit DateCreated: duplicated from Exif DateTimeOriginal Description: duplicated from Exif ImageDescription GPSAreaInformation: duplicated from Exif GPSAreaInformation by copying all the Exif GPS tags to the same-named tags in XMP (-XMP-exif:all<GPS:all) GPSDateTime: duplicated using the composite of Exif GPSDateStamp and Exif GPSTimeStamp GPSLatitude: duplicated using the composite of Exif GPSLatitude and Exif GPSLatitudeRef GPSLongitude: duplicated using the composite of Exif GPSLongitude and Exif GPSLongitudeRef GPSMapDatum: duplicated from Exif GPSMapDatum by copying all the Exif GPS tags to the same-named tags in XMP (-XMP-exif:all<GPS:all) Make: duplicated from Exif Make Model: duplicated from Exif Model ModifyDate: duplicated from Exif ModifyDate PreservedFileName: original image file name, which is unique for each image Rights: duplicated from Exif Copyright UsageTerms: Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty.
To extract the geotagging and survey information (except for the duplicated tags) from the image metadata using ExifTool, the following command can be used (tested with ExifTool version 11.86):
exiftool -csv -filename -EXIF:GPSTimeStamp -EXIF:GPSDateStamp -GPSLatitude -GPSLongitude -n -IPTC:Credit -IPTC:Contact -EXIF:Copyright -XMP:UsageTerms -EXIF:ImageDescription -XMP:AttributionURL -EXIF:GPSAreaInformation -EXIF:GPSMapDatum -EXIF:Artist -ext tif . > out.csv
The "-csv" option writes the information to a CSV file. The "-n" option formats the latitude and longitude as signed decimal degrees. Please note that the above command was tested on macOS; Windows users may need to use "exiftool.exe" instead of "exiftool."

Step 6: Added the missing coordinates for the calibration images collected in 2019 during flights 4 and 6.
During the 2019 survey, the calibration images collected at the start of flights 4 and 6 (2019009FA_m01CAL_20190328T170520Z_IMG_0000_* and 2019009FA_m01CAL_20190328T184445Z_IMG_0000_*) were missing coordinates, so the coordinates from the first calibration image taken at the start of the survey (2019009FA_m01CAL_20190328T155036Z_IMG_0000_1.tif) were used to populate these missing coordinates. The following ExifTool (version 11.86) command was run to populate the missing coordinates in the calibration images:
exiftool -TagsFromFile 2019009FA_m01CAL_20190328T155036Z_IMG_0000_1.tif "-EXIF:GPSLatitude<EXIF:GPSLatitude" "-EXIF:GPSLatitudeRef<EXIF:GPSLatitudeRef" "-EXIF:GPSLongitude<EXIF:GPSLongitude" "-EXIF:GPSLongitudeRef<EXIF:GPSLongitudeRef" -overwrite_original -P -ext tif .

Step 6: Create image location CSV file.
The image details were downloaded for the entire set of photos on this data release from the CMHRP Imagery Data System, providing the exif_data.csv file. The file was parsed for records that contain navigation data for the MicaSense camera. The columns containing the date, time, latitude, longitude and image filename were kept, the rest of the columns were deleted, resulting in a simplified CSV image location file. The file header line was edited to give each column names as described in the attribute information in this metadata file.