[OSM-dev] Website to generate polygons from OSM relations

[Jocelyn Jaubert]

Hi,

I have put into production a website to generate various outputs from
OSM relations, by taking into account inclusion of other relations. It
is available at:

http://polygons.openstreetmap.fr/


What it can do:

 - generate whole geometry from an OSM relation ID, with handling of
sub-relations - this works especially well with the recursive French
model for administrative relations, and can be used as a sanity check.

 - generate simplified geometries, even bigger or smaller - this is
useful to cut a .osm file with a good .poly file.

 - export WKT, .poly, GeoJSON, or even a picture.

 - import a user .poly file, and then do an Union from an OSM relation.
I used this to fix some polygons used for Geofabrik extracts.


A few examples:

OSM relation for Corsica:
  http://polygons.openstreetmap.fr/?id=76910

http://polygons.openstreetmap.fr/get_image.py?id=76910&params=0.020000-0.005000-0.005000

Same thing for France (image is a little longer to generate)
  http://polygons.openstreetmap.fr/?id=1362232

Union of Geofabrik and OSM relation for PACA, a french region:

http://polygons.openstreetmap.fr/get_image.py?id=8654&params=0.020000-0.005000-0.005000&name=provence-alpes-cote-d-azur_5k3mbx

(you can see that some part of the region were missing from the yellow
polygon)


The source code is available at:
https://github.com/jocelynj/osm-polygons-generation

This uses an osmosis database, containing the whole word, and some
Postgis functions. If you have any suggestion, don't hesitate to propose
them !


Thanks,
Jocelyn