[gdal-dev] How to generate COG without loosing Exif, XMP etc metadata

[Luigi Pirelli]

Thank you Javier

good starting point to investigate an eventual fix to gdal :) I'll give
alook!

Luigi Pirelli
mails: luipir at gmail.com
          luigi.pirelli at geobeyond.it
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On Thu, 14 Nov 2024 at 13:18, Javier Jimenez Shaw <j1 at jimenezshaw.com>
wrote:

> In this PR I tried to pass the XMP data when a TIFF copy or COG was done
> https://github.com/OSGeo/gdal/pull/3050
> Maybe it was not complete.
>
> On Thu, 14 Nov 2024 at 13:10, Luigi Pirelli via gdal-dev <
> gdal-dev at lists.osgeo.org> wrote:
>
>> Tnx Even
>>
>> I suspected that -strict was not "complete". In any case My first code
>> version was adding tags over an already generated COG, but the result was
>> an unreadable/broken file in QGIS. I suppose because pyexiv2 is not
>> flexible enough and stuck with a rigid version of tiff structure.
>> I'll try a workaround using some lib or app able to maintain a readable
>> image, tnx for the hint.
>>
>> Luigi Pirelli
>>
>>
>> **************************************************************************************************
>> * LinkedIn: https://www.linkedin.com/in/luigipirelli
>> * Stackexchange: http://gis.stackexchange.com/users/19667/luigi-pirelli
>> * GitHub: https://github.com/luipir
>> * Book: Mastering QGIS3 - 3rd Edition
>> <https://www.packtpub.com/eu/application-development/mastering-geospatial-development-qgis-3x-third-edition>
>>
>> **************************************************************************************************
>>
>>
>> On Thu, 14 Nov 2024 at 13:02, Even Rouault <even.rouault at spatialys.com>
>> wrote:
>>
>>> Luigi,
>>>
>>> The GDAL GeoTIFF or COG drivers have currently no provision for writing
>>> EXIF (the fact that you see Exif.Image.Software is due to, I assume,
>>> exiftool synthetizing that information from the regular Software TIFF tag,
>>> which is propagated), so I don't have any solution to offer. Could
>>> potentially be implemented, but not a 5-minute job.
>>>
>>> "Breaking" the COG structure shouldn't be the end of the world. The
>>> breakage should be minimal. That will just cause one extra HTTP GET to
>>> clients. 95% of the value of COG is just being a tiled GeoTIFF with
>>> overviews. Putting all metadata (including the main TIFF directory) at
>>> beginning of the file is just the cherry on the cake.
>>>
>>> (a quick skim at https://github.com/airbusgeo/cogger which is useful to
>>> COGify a tiled GeoTIFF doesn't show any provision for EXIF, so I don't
>>> think you can use it for your use case)
>>>
>>> The XMP TIFF tag is propagated:
>>>
>>> $ gdal_translate autotest/gdrivers/data/gtiff/byte_with_xmp.tif out.tif
>>> -of cog
>>>
>>> $ gdalinfo out.tif -mdd all | grep XMP
>>> Metadata (xml:XMP):
>>>      <rdf:li>XMP</rdf:li>
>>>
>>> Even
>>> Le 14/11/2024 à 12:39, Luigi Pirelli via gdal-dev a écrit :
>>>
>>> Hi,
>>>
>>> I'm struggling to generate a COG maintaining the original (or at least a
>>> selected subset of) Exif and XMP tags (I ses that Iptc tags are not
>>> propagated at all, but I'm not interested in them).
>>> I used gda_translate via CLI or python and the best option seems -strict
>>> that, theoretically should maintain all original tags.
>>>
>>> But some standard tags are propagated and others not!
>>> e.g.
>>> Exif.Image.Software yes
>>> Exif.Photo.CameraOwnerName no
>>> Exif.Image.Artist yes
>>> Exif.Image.Copyright yes
>>> Exif.Image.DateTimeOriginal no
>>> Exif.Photo.DateTimeOriginal no
>>> Exif.Image.Model no
>>> Exif.Image.CameraSerialNumber no
>>> etc
>>>
>>> It is a bug? a feature? if a bug in any case is there a way to override?
>>> The reason to find a solution is that adding tags over a COG with
>>> "standard" tools like exiftool, exiv2 etc destroy COG structure. So I need
>>> to add or modify tags before converting to COG.
>>>
>>> any suggestion?
>>>
>>> Luigi Pirelli
>>> mails: luipir at gmail.com
>>>            luigi.pirelli at geobeyond.it
>>>
>>>
>>> **************************************************************************************************
>>> * LinkedIn: https://www.linkedin.com/in/luigipirelli
>>> * Stackexchange: http://gis.stackexchange.com/users/19667/luigi-pirelli
>>> * GitHub: https://github.com/luipir
>>> * Book: Mastering QGIS3 - 3rd Edition
>>> <https://www.packtpub.com/eu/application-development/mastering-geospatial-development-qgis-3x-third-edition>
>>>
>>> **************************************************************************************************
>>>
>>> _______________________________________________
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>>> -- http://www.spatialys.com
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>>>
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