[gdal-dev] How to add georeferencing tags to a .tif?
gregcoats at mac.com
Tue Sep 22 11:26:22 EDT 2009
When gdal_translate reads in a GeoTIFF .tif file and writes out a .ppm
file, the user receives a warning message saying that the
georeferencing metadata is not being copied into the output .ppm file,
and is being lost. When gdal_translate reads in a .tif file with TIFF
tag 700 XMP metadata, and TIFF tag 33723 IPTC metadata, and writes out
a .tif or .jp2 file, the user receives no warning that this metadata
is not being copied, and so I was surprised to later learn that the
XMP and IPTC metadata had been lost by gdal_translate.
I suggest that for GDAL 1.7 consideration be given to at least
notifying the user via a warning message that any input .tif file with
TIFF tag 700 XMP metadata, and TIFF tag 33723 IPTC metadata, and TIFF
tag 34665 EXIF metadata will lose that metadata and not have it copied
to the output file. Hopefully, a future GDAL release of gdal_translate
will preserve TIFF tag 700 XMP metadata, and TIFF tag 33723 IPTC
metadata, and the widely used TIFF tag 34665 EXIF metadata that
supports GPS metadata.
The Kakadu applications kdu_compress and kdu_expand, which are
available for free for Win32, Mac OS X, Linux, and Solaris, support
conversions between TIFF/GeoTIFF .tif files and JPEG2000/
GeoJPEG2000 .jp2 while preserving TIFF tag 700 XMP metadata, TIFF tag
33723 IPTC metadata, and TIFF tags 33550, 33922, 34264, 34735, 34736,
34737 georeferencing metadata.
On Sep 8, 2009, at 5:32 PM, Even Rouault wrote:
> 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
> 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.
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