[OSM-dev] New OGR driver to read OpenStreetMap .osm / .pbf files

Even Rouault even.rouault at mines-paris.org
Wed Jul 11 19:22:57 BST 2012


> OSM has *lots* of broken data, especially broken (multi)polygons where:
>
> * polygon rings have gaps

Not sure what you mean by that. Example ?

> * inner/outer polygon rings are mis-classified (inner rings declared as
> outer and vice versa)

The algorithm used in the driver ignores inner/outer declaration, and does a
topological analysis to figure that out.

> * rings touch each other (inner rings touching is indeed a frequent
> thing in OSM and not considered an error)
> * rings intersect

Not sure if this is a problem for the algorithm used. Will have to test that

> If we can't get everyone to use the same code base, then it would at
> least be great to reach some kind of agreement here, or maybe at least
> produce a test suite that everyone runs their code against.

Yes that would be great !

>
> Bye
> Frederik
>
> PS: For starters here's a very simple test case that should result in
> three polygons - a forest polygon with a hole, and a lake and a meadow
> polygon located in that hole:
> http://www.remote.org/frederik/tmp/polygontestcase.osm

Will test that

>
> --
> Frederik Ramm  ##  eMail frederik at remote.org  ##  N49°00'09" E008°23'33"
>
>
>
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