[josm-dev] Wireframe saves the day for a complex multipolygon

Marko Mäkelä marko.makela at iki.fi
Sun Feb 7 19:21:54 GMT 2010


On Sun, Feb 07, 2010 at 02:06:51PM -0500, Matthias Julius wrote:
> >> I followed the example on the wiki page
> >> http://wiki.openstreetmap.org/wiki/Relation:multipolygon
> >> which does suggest that lakes within islands can be defined as role=outer:
> >
> > I wrote that Wiki page and I still think it makes sense. This method 
> > (where there may be additional outers inside inners) also conforms to 
> > the OGC "simple features" geometry rules, i.e. "everybody does it".
> 
> This might be correct use of the Multipolygon relation, but is the lake
> on the island really part of the outer lake?
> 
> If it is a separate lake with its own name I would say it should be a
> separate object for OSM.

I think that the lakes-within-islands would be separate lakes, and thus
Jiri is right: they should be excluded from the big-lake multipolygon.
When they were included in role=outer, mkgmap gave them the name of the
multipolygon.

Someone already fixed this by removing the lakes-within-islands from the
multipolygon relation and by removing natural=land from the islands, so that
the islands would be "empty" and no multipolygons will be needed for them.
The proper solution would be to keep the natural=land and define separate
multipolygons for each island that contains lakes.  I might do that later.

Thanks to Frederik for the exact "Download URL" tip.  It would be helpful
if JOSM would accept the http://api.openstreetmap.org/api/0.6/relation/402543
also on the command line.  It would also be very helpful if JOSM rewrote
the following types of URLs to API urls:
http://www.openstreetmap.org/browse/relation/402543
http://www.openstreetmap.org/?relation=402543

	Marko




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