[gdal-dev] DXF MLTIPOINT

[Rahkonen Jukka]

Hi,

  *   The main question is why...
Those who have written the DXF driver (Frank Warmerdam, Alan Thomas, Even Rouault...) may know why but I guess that that their client did not have multipoints in their data, or they were not willing to pay for something that they do not need. Multipoints are not so common in GIS. Open Source tends to work so that a developer writes something that is good enough for their own, or their customers' needs. Then they put the results available for others, who may find the code usable.

-Jukka Rahkonen-

Lähettäjä: Michał Kowalczuk <michkowalczuk at gmail.com>
Lähetetty: torstai 16. tammikuuta 2025 10.11
Vastaanottaja: Rahkonen Jukka <jukka.rahkonen at maanmittauslaitos.fi>
Kopio: gdal-dev at lists.osgeo.org
Aihe: Re: [gdal-dev] DXF MLTIPOINT

Thank you, Jukka.
I saw this post. The main question is why the DXF driver implementation can explode MultiPolylines and MultiPolygons (which is more complex) and MultiPoint not?

Michał Kowalczuk

czw., 16 sty 2025 o 08:24 Rahkonen Jukka <jukka.rahkonen at maanmittauslaitos.fi<mailto:jukka.rahkonen at maanmittauslaitos.fi>> napisał(a):
Hi,

By this gis.stackexchange answer https://gis.stackexchange.com/questions/336804/export-to-dxf-from-multipoint-z-geometry-in-postgresql-using-ogr2ogr the main issue is in the DXF format that does not support MultiPoints. Try the workaround and explode your multipoints.
About why it is allowed to create a geometry type that is not supported by the driver, I do not know if the validity of the geometry type is checked https://gdal.org/en/stable/api/python/raster_api.html#osgeo.gdal.Dataset.CreateLayer of if it up to user to know that, or if DXF is a special case.

-Jukka Rahkonen-

Lähettäjä: gdal-dev <gdal-dev-bounces at lists.osgeo.org<mailto:gdal-dev-bounces at lists.osgeo.org>> Puolesta Michal Kowalczuk via gdal-dev
Lähetetty: torstai 16. tammikuuta 2025 8.56
Vastaanottaja: gdal-dev at lists.osgeo.org<mailto:gdal-dev at lists.osgeo.org>
Aihe: [gdal-dev] DXF MLTIPOINT


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Hi,
Does anyone know why DXF driver supports writing MutiLine and Multipolygon (make automatic conversion) but MultiPoint is not...?
If so, why layer creation (GDALDatasetCreateLayer) with this geometry type (wkbMultiPoint... family) is allowed and the error occurs only when creating a feature on a layer (OGR_L_CreateFeature)?

CPLError: No known way to write feature with geometry 'Multi Point'.

The DXF driver documentation is silent about this type of geometry...

Regards,
Michał Kowalczuk
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