Problem with tags of members of relation multipolygon

[zimirrr]

There is relation that consists of closed polygons with their own tags. (​http://www.openstreetmap.org/relation/331364#map=14/45.2400/6.0782) This relation has this tags:

name=Les 7 Laux
type=multipolygon

And one of it's member has tags:

name=Lac du Cos
natural=water
water=lake

As member of the relation this object has Role=Outer.

When I import osm file with this relation into postgresql or simply open it with qgis I get it's member in MultiPolygon and tags of the relation, not member's own tags.

After I dropped it's role=outer it duplicates with it's own tags and as a member of bigger MultiPolygon.

I am not very good in OSM and do not know whether that relation is wrong but I need such polygons with it's own tags.

I also imported this relation with osm2pgsql and this object has it's own tags.

ogr2ogr: GDAL 2.1.2, released 2016/10/24 Qgis: 2.14.17-Essen Compiled against GDAL/OGR 2.2.1

[Jukka Rahkonen]

It feels like an "old-style" multipolygon and the aim is to correct them in OSM ​http://area.jochentopf.com/. Osm2pgsql will also drop the support for such tagging soon ​https://lists.openstreetmap.org/pipermail/dev/2017-September/029999.html.

Therefore "tags of the relation" is right. Feel free to fix the tagging in OSM.

[Even Rouault]

The issue here is that way id="35776998" has "interesting tags", such as name=Lac Du Cos, but is part of relation id="331364" "Les 7 Laux", which is a logical gathering of several lakes. Currently when the OGR OSM driver sees that one of the member of a relation has a role="outer" it thinks it is OK to not expose it as a standalone polygon, but just keep it in the multipolygon.

I'm not sure it is really an 'old-style' multipolygon issue, since both the way and the relation have a distinct name. Probably that in that case GDAL should emit the way as a standalone polygon, in addition to incorporating it into the multipolygon. Probably with some option in the osmconf.ini to control this

[Jukka Rahkonen]

Perhaps the group of lakes should be modelled as some other relation type than multipolygon. The "site" relation ​http://wiki.openstreetmap.org/wiki/Relations/Proposed/Site might be usable.

Taking the members with role "outer" and exposing them as separate polygons may not cover all cases. For example just this relation has also relations as members (couple of lakes with islands - what if the island has a name as well?), and members in role "outer" are not always closed ways but they can also be lines, each line perhaps with its own tags.

[Even Rouault]

This ticket has been automatically closed because Trac is no longer used for GDAL bug tracking, since the project has migrated to GitHub. If you believe this ticket is still valid, you may file it to ​https://github.com/OSGeo/gdal/issues if it is not already reported there.