NAME

       gpscorrelate - correlates digital images with GPS data filling EXIF fields

SYNOPSIS

       gpscorrelate [-z | --timeadd +/-HH[:MM]] [-O | --photooffset seconds] [-i |
                    --no-interpolation] [-v | --verbose] [-d | --datum datum] [-n | --no-write]
                    [-R | --replace] [-m | --max-dist time] [-t | --ignore-tracksegs] [-M |
                    --no-mtime] [--degmins] [-g file.gpx |
                    [-l | --latlong] latitude,longitude[,elevation]] image.jpg...

       gpscorrelate -s | --show | -o | --machine  image.jpg...

       gpscorrelate {-r | --remove} [-M | --no-mtime] image.jpg...

       gpscorrelate {-f | --fix-datestamps} {-z | --timeadd +/-HH[:MM]} image.jpg...

       gpscorrelate -V | --version | -h | --help

DESCRIPTION

       This manual page documents the gpscorrelate command. There is extended documentation
       available in HTML format; see below.

       gpscorrelate is a program that acts on digital images in JPEG format, filling in the EXIF
       (Exchangeable Image File Format) fields related to GPS (Global Positioning System)
       information. Source for the GPS data is a GPX (GPS Exchange Format) file, which records
       GPS location information in an XML-based format. The act of filling those fields is
       referred to as correlation.

       If GPS data are available at the precise moment the image was taken (with a 1-second
       granularity) the GPS data are stored unmodified in EXIF fields. If they are not, linear
       interpolation of GPS data available at moments before and after the image was taken can be
       used. A measure of the approximate accuracy of the GPS location reading is preserved when
       written into the image.

OPTIONS

       These programs follow the usual GNU command line syntax, with long options starting with
       two dashes (`-'). A summary of options is included below.

       -g, --gps file.gpx
           Correlate images using the specified GPX file containing GPS track points. This option
           can be given many times to specify multiple GPX files. For each photo being
           correlated, the first file containing a track covering the time the photo was taken
           will be the one used. All <trk> segments in each file are used.

       -l, --latlong latitude,longitude[,elevation]
           Provide a specific geographic coordinate to use for all images instead correlating
           along a path in a GPX file. The format must be of the general form
           latitude,longitude,elevation where latitude and longitude must each be in either
           decimal form, such as -123.45678 or in degrees/minutes/seconds form, such as
           -123°45'67.8" or -123d45m67s. Providing an elevation is optional. Each component can
           be separated by commas, spaces or tabs.

           Note that this option has a known bug in that it does not parse numbers correctly in
           locales that use other than "." as a decimal separator.

       -s, --show
           Only show the GPS data already in the given image's EXIF tags instead of correlating
           them.

       -o, --machine
           Only show the GPS data of the given images in a machine-readable CSV format. Images
           without GPS tags are ignored. The fields output are file name, date and time,
           latitude, longitude, elevation, where the first value is the filename, as passed, the
           second is the timestamp, and the last three are floating point values with an optional
           leading plus or minus.

       -r, --remove
           Remove all GPS EXIF data from the given images. Note that this only removes the GPS
           tags that the program could add; it does not delete all possible GPS EXIF tags. All
           other tags are left alone.

       -z, --timeadd +/-HH[:MM]
           Time to add to GPS points to make them match the timestamps of the images. GPS
           timestamps are in UTC; image timestamps are generally in local time. Enter the
           timezone used when taking the images; e.g., +8 for Perth, Western Australia or -2:30
           for St. John's, Newfoundland. This defaults to the UTC offset of the local time zone
           as of the time of the first image processed (versions before 1.7 defaulted to 00:00).

       -O, --photooffset seconds
           Time in seconds to add to the photo timestamp to make it match the GPS timestamp. To
           determine the number of seconds needed, just create a photograph of your GPS device
           showing the current time and compare it with the timestamp of your photo file. The
           EXIF time tags in the image are not modified based on this value.

       -i, --no-interpolation
           Disable linear interpolation between points. With this flag, the nearest exact point
           (within --max-dist) is used. Without this flag, photos taken between the time of two
           recorded GPS coordinates are correlated based on linear interpolation between those
           two points.

       -v, --verbose
           Show slightly more information during the image correlation process, such as the GPS
           data selected for each image.

       -d, --datum datum
           Specify GPS measurement datum. If not set, WGS-84 is used (TOKYO is another
           possibility). However, GPX is not supposed to store anything but WGS-84, so this
           should only ever be needed with the --latlong option.

       -n, --no-write
           Do not write the correlated EXIF data back into the image. Useful with --verbose to
           see what would happen during image correlation.

       -R, --replace
           Overwrite any existing GPS tags in the file. Without this option, any file that
           already contains GPS tags will be skipped.

       -m, --max-dist time
           Maximum time in seconds from the photo time which a logged GPS point can refer and
           still be used for correlation. This defaults to 0, which means to disable this check.
           Only one of the two points need be within this range for correlation to take place.

           If the accuracy of the location is paramount and you would rather not correlate a
           position for a photo at all if the nearest GPS coordinates were recorded too long ago
           in the past or too far into the future (relative to when the photo was taken), then
           set this to a nonzero value.

       -t, --ignore-tracksegs
           Interpolate between track segments, too. Generally, track segments show multiple
           sessions of GPS logging; between them is generally when the GPS was not logging. Since
           interpolation honours the --max-dist flag, even track segments with wide time gaps can
           safely be used if both flags are set. Without this flag, photos taken within the time
           gap between two <trkseg> tracks in the GPX file are not correlated.

       -M, --no-mtime
           Do not change the last modification time of changed files.

       -f, --fix-datestamps
           Fix broken GPS datestamps written with gpscorrelate versions < 1.5.2 by replacing them
           with the photo's time stamp. Prior to 1.5.2, two bugs wrote the wrong value for the
           GPSDateStamp and GPSTimeStamp tags. This option will check each supplied filename for
           the problem and correct it. Use with --no-write to prevent writing these changes
           (useful for checking for the issue). This option also implies --no-mtime. You will
           also need to use --timeadd to specify the difference between localtime and UTC time
           for the supplied photos.

       --degmins
           Write location as DD MM.MM (instead of the more accurate DD MM SS.SS) as was the
           default in gpscorrelate versions < 1.5.3. There is no good reason to use this option
           unless some broken program expects this style.

       -h, --help
           Only show a summary of options.

       -V, --version
           Only print the gpscorrelate version number and copyright information.

EXAMPLES

       To correlate all photos in a directory taken in western Europe in the summer (i.e.,
       UTC-2):

       gpscorrelate -g Test.gpx -z 2 *.jpg

       To correlate all photos in a directory taken in Italy, switching to UTC-2 or UTC-1
       depending on the daylight savings time in effect when the first picture in the list was
       taken:

       env TZ=Europe/Rome gpscorrelate -g Test.gpx *.jpg

       Correlate all photos in a directory from a track spread out over two different track files
       and taken in the computer's current time zone, interpolating between segments and between
       files while ignoring photos taken too far away from a recorded point, without changing the
       file time stamp of the files, while showing details of the process:

       gpscorrelate -g track1.gpx -g track2.gpx -m 120 -t -M -v *.jpg

       To correlate a photo taken from a camera with a fast clock (i.e., the clock was 77 seconds
       ahead of GPS time):

       gpscorrelate -g Test.gpx -O -77 photo.jpg

       Show existing GPS tags in a photo:

       gpscorrelate --show photo.jpg

       Show existing GPS tags in a photo and output in CSV format:

       gpscorrelate --show --machine photo.jpg

       Remove GPS tags from photos:

       gpscorrelate --remove *.jpg

       Add a GPS location tag to a photo taken at Ulmer Münster:

       gpscorrelate -l 48.398620,9.991417,522 -z 2 ulm.jpg

EXIT STATUS

       gpscorrelate returns 0 in case of success, 1 in case of major error (such as a read or
       write error) and 2 in case of minor error (such as the given GPS track not covering the
       time of an image).

SEE ALSO

       gpsd(1), gpsbabel(1), gpxlogger(1), cgpxlogger(1).

       The documentation of gpscorrelate in HTML format is available on the filesystem at
       /usr/share/doc/gpscorrelate.

LICENSE

       This manual page was initially written by Stefano Zacchiroli <zack@debian.org> for the
       Debian(TM) system. It was extended by Till Maas <opensource@till.name> and Dan Fandrich
       <dan@coneharvesters.com>. Permission is granted to copy, distribute and/or modify this
       document under the terms of the GNU General Public License, Version 2 or any later version
       published by the Free Software Foundation.

AUTHOR

       Stefano Zacchiroli
           Author.

COPYRIGHT

       Copyright © 2006-2019 Stefano Zacchiroli <zack@debian.org>, Till Maas, Dan Fandrich