[gdal-dev] Un-vendoring a number of third-party libraries?

[Even Rouault]

Le 29/12/2023 à 22:10, Nyall Dawson a écrit :
>
>
> On Sat, 16 Dec 2023, 1:03 am Even Rouault via gdal-dev, 
> <gdal-dev at lists.osgeo.org> wrote:
>
>
>     Le 15/12/2023 à 15:49, Sebastiaan Couwenberg via gdal-dev a écrit :
>     > On 12/15/23 15:35, Even Rouault via gdal-dev wrote:
>     >> Thoughts ? (given the length of the email, it should probably be
>     >> formalized as a RFC. I'll do that, unless there is a massive
>     uprising
>     >> against the proposal...)
>     >
>     > LERC doesn't support big endian architectures currently, only using
>     > that on little endian architectures using the internal copy
>     currently
>     > works as expected. Using the external library would require
>     > conditionals in the packaging which I'm not in favor of.
>     Bas,
>
>     - The Debian libtiff package already handles that conditional, so
>     there
>     must certainly be a way of using the same trick for the GDAL build
>     recipee
>
>     - The only user of LERC in GDAL (except for its libtiff internal
>     cpoy)
>     is the MRF driver. I doubt MRF is used widely except in Esri data
>     centers... So even if you don't want to change the GDAL build
>     recipee to
>     include a conditional liblerc dependency, that wouldn't be the end of
>     the world.
>
>
> Some ESRI image server layers are served up using lerc compression, eg 
> the landcover tiles:
>
> https://tiledimageservices.arcgis.com/P3ePLMYs2RVChkJx/arcgis/rest/services/Esri_2020_Land_Cover_V2/ImageServer?f=pjson
>
> I was planning on doing some future work in qgis to support reading 
> these layers by using gdal to do the lerc decompression, so I'd be 
> disappointed if the lerc compression support is dropped.

Hi Nyall,

Interesting. Digging a bit more, I now see that the MRF driver can open 
Lerc blobs too (independently of the MRF extra stuff), so that can 
potentially be a way to get Lerc decompression working. And actually 
there's is a test in the WMS driver that uses MRF/LERC 
(https://github.com/OSGeo/gdal/blob/master/autotest/gdrivers/wms.py#L872) 
which might be just what you need.

It would be nice if the GDAL Debian package could link liblerc in the 
future.

Even


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