[OSM-dev] Polygon inner/outer relation in osm file

Martin Koppenhoefer dieterdreist at gmail.com
Tue Aug 23 13:58:02 UTC 2016

sent from a phone

> Il giorno 23 ago 2016, alle ore 15:21, Frederik Ramm <frederik at remote.org> ha scritto:
> they can have missing or wrong inner/outer tags
> (usually considered valid)... the C++/Python library "osmium" is
> probably the most advanced in building proper polygons, or check out
> osm2pgsql, imposm, or ogr2ogr which also have code to deal with that.

recently we stumbled upon problematic behavior of current multipoligon processing in osm-carto, as it drops tags on inner relation members if the outer members (or the relation?) has the same tags. I believe this kind of "fix" should not be performed, it leads to problems if this kind of mapping was done on purpose, e.g. because of some properties being different.

Not applying "magic guesswork" also leads to more predictable behavior and ultimately to mappers fixing the representation in case it was wrong.


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