[gdal-dev] ExportToGML with compound CRS

[Joep Keijsers]

Thanks for the quick patch! After building from the PR branch, I can confirm that it correctly returns the compound CRS for both approaches.

Joep

________________________________
From: Rahkonen Jukka <jukka.rahkonen at maanmittauslaitos.fi>
Sent: 15 April 2026 17:28
To: Joep Keijsers <joep.keijsers at sogelink.com>; gdal-dev at lists.osgeo.org <gdal-dev at lists.osgeo.org>; Even Rouault <even.rouault at spatialys.com>
Subject: Re: [gdal-dev] ExportToGML with compound CRS

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Hi

Even made a fix already but here is a command for testing with the old school CLI.

ogr2ogr -f gml -a_srs EPSG:5973 compound.gml :memory: -sql "select 1 as id, st_geomfromtext('POINTZ (1 1 1)') as geom" -nln test

"boundedBy" seems to receive
 srsName="urn:ogc:def:crs:EPSG::5973 but the geometry itself srsName="urn:ogc:def:crs:EPSG::11023"

-Jukka Rahkonen-

________________________________________
Lähettäjä: gdal-dev <gdal-dev-bounces at lists.osgeo.org> käyttäjän Even Rouault via gdal-dev <gdal-dev at lists.osgeo.org> puolesta
Lähetetty: Keskiviikko 15. huhtikuuta 2026 18.25
Vastaanottaja: Joep Keijsers <joep.keijsers at sogelink.com>; gdal-dev at lists.osgeo.org <gdal-dev at lists.osgeo.org>
Aihe: Re: [gdal-dev] ExportToGML with compound CRS


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Hi,

no other workaround but applying
https://github.com/OSGeo/gdal/pull/14367 (or post patching the output)

Even

Le 15/04/2026 à 16:53, Joep Keijsers via gdal-dev a écrit :
> Greetings,
>
> I'm trying to export a geometry object to GML using the Python API. The geometry has a compound CRS (EPSG:5973). When exporting to GML, the vertical component of the compound CRS is dropped, although the Z-values are still there. For example:
>
> from osgeo import ogr, osr
>
> # Create geometry from WKT string
> srs = osr.SpatialReference()
> srs.ImportFromEPSG(5973)
> wkt = "POINT (30 10 5)"
> geometry = ogr.CreateGeometryFromWkt(wkt, srs)
>
> # Export to GML
> xml = geometry.ExportToGML(options=['FORMAT=GML32', 'SRSDIMENSION_LOC=GEOMETRY', 'SRSNAME_FORMAT=SHORT', 'GMLID=TestPoint-1'])
> print(xml)
>
> ... which returns EPSG:11023 instead of EPSG:5973:
>
> <gml:Point srsName="EPSG:11023" srsDimension="3" gml:id="TestPoint-1"><gml:pos>30 10 5</gml:pos></gml:Point>
>
> I believe this EPSG code change happens in this line: https://github.com/OSGeo/gdal/blob/30e7918f245022983d84f93f1a53641fd50337ed/ogr/ogr2gmlgeometry.cpp#L562.
>
> Is there a way to keep the compound CRS in the GML output?
>
> Version info: gdal 3.12.3
>
> Thanks!
>
> Joep
>
>
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> gdal-dev at lists.osgeo.org
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