[gdal-dev] How to add georeferencing tags to a .tif?

[Even Rouault]

Selon Greg Coats <gregcoats at mac.com>:

> I have one .tif that has tag 700 XMP metadata, and has a tag 33723
> IPTC metadata, but does not have tags 33550, 33922, 34264, 34735,
> 34736, 34737 georeferencing metadata. I have a second .tif that has
> does not have tag 700 XMP metadata, nor does it have tag 33723 IPTC
> metadata, but it does have 33550, 33922, 34264, 34735, 34736, 34737
> georeferencing metadata. I want to add the tags that provide
> georeferencing metadata in the second .tif, to the first .tif. As
> shown below, I first tried using geotifcp, and then tried
> gdal_translate, but while the resulting .tif does have the
> georeferencing tags it originally lacked, the resulting .tif is
> without the tag 700 XMP metadata, and without the tag 33723 IPTC
> metadata that it originally had. How can georeferencing tags be added
> to a .tif, withOUT removing preexisting tag 700 XMP metadata, and
> withOUT removing preexisting tag IPTC 33723 metadata?
> listgeo 18stj940125.tif > 18stj940125_listgeo.txt
> geotifcp -s -r 1 -c none -f msb2lsb -g 18stj940125_listgeo.txt
> tif_withXMP700_withIPTC33723_withoutGeo.tif
> tif_withXMP700_withIPTC33723_withGeo.tif

Those 700 XMP and 33723 IPTC tags are not handled by the GTiff driver neither in
read nor in write mode, so that explains why gdal_translate doesn't copy them.
You could probably try the 'tiffset' utility to set them afterwards. Or hack
geotifcp.c to add support for those 2 tags. The tags[] array looks like an
interesting place where to hack that in.

> Greg
>