gpsexiftool

Why are the position values of the GPS information in the image metadata stored as "Composite" by exiftool

Why are the position values of the GPS information in the image metadata stored as "Composite" by ExifTool 12.57?

E.g.:

image=/path/to/photo.jpg

exiftool -G0 '-gps.*' "${image}"

[EXIF]          GPS Latitude Ref                : North
[EXIF]          GPS Longitude Ref               : East
[EXIF]          GPS Altitude Ref                : Above Sea Level
[EXIF]          GPS Speed Ref                   : km/h
[EXIF]          GPS Speed                       : 0
[EXIF]          GPS Img Direction Ref           : True North
[EXIF]          GPS Img Direction               : 152.5745659
[EXIF]          GPS Dest Bearing Ref            : True North
[EXIF]          GPS Dest Bearing                : 104.1544711
[EXIF]          GPS Date Stamp                  : 2021:10:10
[EXIF]          GPS Horizontal Positioning Error: 44 m
[Composite]     GPS Altitude                    : 102 m Above Sea Level
[Composite]     GPS Latitude                    : 40 deg 41' 5.29" N
[Composite]     GPS Longitude                   : 16 deg 41' 23.70" E
[Composite]     GPS Position                    : 40 deg 41' 5.29" N, 16 deg 41' 23.70" E

I'm asking because they are actually entirely part of the EXIF 2.32 specification:

enter image description here

Source: https://web.archive.org/web/20190624045241if_/http://www.cipa.jp:80/std/documents/e/DC-008-Translation-2019-E.pdf

Solution

  • This is exiftool FAQ #3

    First, make sure you are looking at the right information. Use ExifTool with a command like this to extract all information from the file, along with the location it was written:

    exiftool -a -G1 -s c:\images\test.jpg

    In this command, -a allows duplicate tags to be extracted, …

    When duplicate tags exist, only one is extracted unless the -a option is used. Beware that options like -EXIF:all select all EXIF tags from the extracted tags, so EXIF tags hidden by duplicate tags in other locations will not appear in the output for -EXIF:all.

    When exiftool encounters a duplicate tag name and the -a (-duplicates) option is not used, then the tag displayed will be that last one read. Composite tags are created last after all the other tags are read, so they will always be the listed ones when -a is not used.