[OSM-dev] Relation member_roles from Osmosis import

Frank Broniewski brfr at metrico.lu
Thu Oct 28 13:48:12 BST 2010

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"
>> 22852;"forward_stop_0"
>> 22852;"forward_stop_11"
>> 22852;"forward_stop_19"
>> 22852;"forward_stop_9"
>> 22852;"stop_1"
>> 22852;"stop_10"
>> 22852;"stop_12"
>> 22852;"stop_13"
>> 22852;"stop_14"
>> 300710;"backward_stop_%n"
>> 207675;"forward_stop_%n"
>> 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.
> Jochen


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