[OSM-dev] Relation member_roles from Osmosis import
jochen at remote.org
Fri Oct 29 09:14:22 BST 2010
Common. There are many, many broken multipolygon relations. See
Whatever you do with OSM data you have to take into account that its not
perfect and work around that.
On Thu, Oct 28, 2010 at 02:48:12PM +0200, Frank Broniewski wrote:
> Date: Thu, 28 Oct 2010 14:48:12 +0200
> From: Frank Broniewski <brfr at metrico.lu>
> To: Jochen Topf <jochen at remote.org>
> CC: dev at openstreetmap.org
> Subject: Re: [OSM-dev] Relation member_roles from Osmosis import
> Hello Jochen,
> thanks for your answer, that makes it clear. I have another question
> about relations.
> I found a relation, a lake in Germany, (id=1104680, Schweriner See
> (Außensee)), which has serveral inner relations to ways. Some of these
> ways form a closed ways, so it's easy to create a polygon from it. But
> other ways with the relation role "inner" are not closed, but they form
> together an island in the lake.
> Should't those form a relation of themselves before relating them to the
> lake relation with an inner relation? The ways I am speaking of are
> Luckily those ways form an island but if there would be another island
> formed by ways without relating them together it is quite difficult to
> recreate them properly. Is this situation an exception or is this a
> common situation?
> Am 27.10.2010 11:01, schrieb Jochen Topf:
>> On Wed, Oct 27, 2010 at 10:39:38AM +0200, Frank Broniewski wrote:
>>> During my examinations from an OSM import (osmosis pbf to postgis) I
>>> found some strange looking entries in the relation_members table. My
>>> goal is to make (GIS) polygons from the linestrings table and therefore
>>> I examined the relations a little closer.
>>> Doing a
>>> select distinct relation_id, member_role from relation_members
>>> I find these entries in the result, which I suspect to be wrong
>>> "relation_id", "member_role"
>>> I think that numbering the member_role is not the intended way ;-)
>> Thats a left-over from the time when relation members were not ordered.
> Frank BRONIEWSKI
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Jochen Topf jochen at remote.org http://www.remote.org/jochen/ +49-721-388298
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