The image files were renamed using a custom python script. The file names were formed using the following pattern Fx-YYYYMMDDThhmmssZ_Ryz.*, where:
- Fx = Flight number
- YYYYMMDDThhmmssZ = date and time in the ISO 8601 standard, where 'T' separates the date from the time, and 'Z' denotes UTC ('Zulu') time.
- Ry = RA or RB to distinguish camera 'RicohA' from 'RicohB'
- z = original image name assigned by camera during acquisition
- * = file extension (JPG)
The approximate image acquisition coordinates were added to the image metadata (EXIF) ('geotagged') using the image timestamp and the telemetry logs from the UAS onboard single-frequency 1-Hz autonomous GPS. The geotagging process was done using the Geosetter software package. To improve timestamp accuracy, the image acquisition times were adjusted to true ('corrected') UTC time by comparing the image timestamps with several images taken of a smartphone app ('Emerald Time') showing accurate time from Network Time Protocol (NTP) servers. For this survey, + 00:00:01 (1 second) was added to the image timestamp to synchronize with corrected UTC time. The positions stored in the EXIF are in geographic coordinates referenced to the WGS84(G1150) coordinate reference system (EPSG:4979), with elevation in meters relative to the WGS84 ellipsoid.
Additional information was added to the EXIF using the command-line 'exiftool' software with the following command:
exiftool ^
-P ^
-IPTC:Credit="U.S. Geological Survey" ^
-IPTC:Contact="pcmsc_data@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="Low-altitude aerial image of the Los Padres Reservoir delta area, Carmel River valley, California, USA, from USGS field activity 2017-635-FA;
https://cmgds.marine.usgs.gov/fan_info.php?fan=2017-635-FA" ^
-XMP:Event="Unoccupied Aircraft System survey of Los Padres Reservoir delta area during USGS field activity 2017-635-FA." ^
-EXIF:GPSAreaInformation="Position from UAS onboard autonomous single-frequency GNSS." ^
-EXIF:GPSMapDatum="EPSG:4979 (WGS 84)" ^
-EXIF:Artist="U.S. Geological Survey, Pacific Coastal and Marine Science Center" ^
-IPTC:CopyrightNotice="Public Domain. Please credit U.S. Geological Survey." ^
-IPTC:Caption-Abstract="Aerial image of the Los Padres Reservoir delta area and Carmel River, Carmel River valley, California, USA, from an Unoccupied Aircraft System (UAS) during USGS field activity 2017-635-FA." ^
-sep ", " ^
-keywords="Carmel River, Los Padres Reservoir, Monterey County, California, 2017-635-FA, Unoccupied Aircraft System, UAS, drone, aerial imagery, U.S. Geological Survey, USGS, Pacific Coastal and Marine Science Center" ^
-comment="Aerial image of the Los Padres Reservoir delta area and Carmel River, Carmel River valley, California, USA, from an Unoccupied Aircraft System (UAS) during USGS field activity 2017-635-FA."^
-Orientation= ^
-XMP:AttributionURL="
https://doi.org/10.5066/P9J9CHOH" ^
-OffsetTime*=+00:00 -AllDates+=7 ^
-r f* ^
-ext DNG ^
-ext JPG
Additional metadata tags were populated in the imagery metadata using the following command:
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 ^
-ext JPG