Longituderef in .jpg and .xmp difference

[Alan Clifford]

Hi Phil,  I've tried to reduce to the specific point.

The result from the code below produces different results for .jpg and .xmp, with the longituderef being ignored for the .xmp file.  Or maybe I am using the fields incorrectly?

alan@coprolith:gpslongitudetest$ ./longitudetest.sh
    1 image files updated
GPS Longitude                   : 62 deg 3' 34.19" E
GPS Longitude Ref               : East
    1 image files updated
GPS Longitude                   : 62 deg 3' 34.19" W
GPS Longitude Ref               : West



#!/bin/bash

exiftool -m -P  \
      -gpslongitude=62.05949817909090909080  -gpslongituderef=West \
      -overwrite_original -previewimage= \
      dscf1881.avi.xmp

exiftool -gpslongitude  -gpslongituderef dscf1881.avi.xmp


exiftool -m -P  \
      -gpslongitude=62.05949817909090909080  -gpslongituderef=West \
      -overwrite_original -previewimage= \
      dscf1882.jpg

exiftool -gpslongitude  -gpslongituderef dscf1882.jpg

[Alan Clifford]

I think I see.  XMP fields are different from exif fields.

Alan

... later

I think maybe it would make sense if I used xmp:longitude with signed numbers for both file types

Alan

[Phil Harvey]

Hi Alan,

Glad you figured this out.

I would recommend using EXIF for GPS in JPEG since more applications will recognize this information.

In XMP files, with the -G1 option you will see that the GPSLatitude/LongitudeRef tags are Composite.  These are not writable, and are generated only to facilitate copying XMP GPS to EXIF.

- Phil

[Alan Clifford]

I think I have got myself sorted.  As I can't update .avi and .mov, I'm using a sidecar xmp file.

A small query.  I am now writing both xmp and exif gps stuff to the file.  If the file happens to be the sidecar file, exiftool doesn't seem to object that I am trying to write exif stuff to the xmp file in my bash script.  Is that OK?

    exiftool -m -P  -exif:gpslatitude=${gpslatitude} -exif:gpslatituderef=${gpslatituderef} \
      -exif:gpslongitude=${gpslongitude}  -exif:gpslongituderef=${gpslongituderef} \
      -exif:gpsaltitude=${gpsaltitude} -exif:gpsaltituderef=${gpsaltituderef} \
      -exif:gpsdatestamp=${gpsdatestamp} -exif:gpstimestamp=${gpstimestamp} \
      -xmp:gpslatitude=${xmpgpslatitude} \
      -xmp:gpslongitude=${xmpgpslongitude} \
      -xmp:gpsaltitude=${gpsaltitude} -xmp:gpsaltituderef=${gpsaltituderef} \
      -xmp:gpsdatetime="${xmpgpstimestamp}" \
      -overwrite_original -previewimage= \
      "$xmpphoto"  >&2


At the end of the day, I'm using the Perl and the api to extract $gpsposition and it seems to be working now for both file types.


Alan

[Phil Harvey]

Hi Alan,

A small query.  I am now writing both xmp and exif gps stuff to the file.  If the file happens to be the sidecar file, exiftool doesn't seem to object that I am trying to write exif stuff to the xmp file in my bash script.  Is that OK?

Yes, this is fine.  FAQ 23 touches on this subject.

At the end of the day, I'm using the Perl and the api to extract $gpsposition and it seems to be working now for both file types.

Sounds good.  The Composite GPSPosition tag is designed to be valid for both types of metadata.

- Phil