[OSM-dev] Extracting just national boundaries

Curt Nowak nowak at bwl.uni-hildesheim.de
Thu Aug 11 08:13:21 BST 2011


Hi Markus,

you were right. I tried osmfilter and so far it seems that it has worked as expected. Thanks for your help.

Curt

PS: Why is there that strict limit of parsing an osm file up to 12 times?


-----Ursprüngliche Nachricht-----
Von: marqqs at gmx.eu [mailto:marqqs at gmx.eu]
Gesendet: Sonntag, 7. August 2011 20:13
An: Curt Nowak; dev at openstreetmap.org
Betreff: Re: [OSM-dev] Extracting just national boundaries


Hi Curt,

> 1.Run: Read all relations and store their dependencies (maybe in a
> very simple database, or even in RAM) Then figure out which relations
> you *really* need. 2. Run: Filter these relations.

This is a good description of osmfilter's algorithm. ;-) The program stores the interrelation dependencies in a temporary file and parses this file up to 12 times.

> If I have enough time (likely I won't) I might try to write an osmosis
> plugin for this.

Why? I thought, Osmosis would already be able to perform this task...?

Markus


-------- Original-Nachricht --------
> Datum: Sun, 7 Aug 2011 19:25:51 +0200
> Von: Curt Nowak <nowak at bwl.uni-hildesheim.de>
> An: "dev at openstreetmap.org" <dev at openstreetmap.org>
> Betreff: Re: [OSM-dev] Extracting just national boundaries

> Hello Igor and Peter,
>
> I'll take a look into --cascading-relations. Maybe I can adapt
> something from there. I'm thinking it should be possible in two
> consecutive runs over a pbf/osm
> file:
>
> 1.Run: Read all relations and store their dependencies (maybe in a
> very simple database, or even in RAM) Then figure out which relations
> you *really* need. 2. Run: Filter these relations.
>
> If I have enough time (likely I won't) I might try to write an osmosis
> plugin for this.
>
> Thanks for your help.
>
> Curt
>
> ________________________________________
> From: Igor Podolskiy [igor.podolskiy at vwi-stuttgart.de]
> Sent: 06 August 2011 17:44
> To: dev at openstreetmap.org
> Subject: Re: [OSM-dev] Extracting just national boundaries
>
> Hi,
>
> On 06.08.2011 17:38, Peter Körner wrote:
> > Am 05.08.2011 17:24, schrieb Igor Podolskiy:
> >> Basically, to implement a
> >> --used-relations you need to compute the transitive closure of a
> >> possibly cyclic graph with relations as nodes and memberships as
> >> edges, and this is not trivial if all you have is a data stream and
> >> no loops - which is the Osmosis model.
> >
> > Osmosis does something very similar in its --cascading-relations
> > option, did you try that?
> yes, I know about --cascading-relations, but it's a --bounding-box
> option, not a standalone task. On the other hand, you're right, you
> always could do something like
>
> --bbox -90,-180,90,180 cascading-relations=yes
>
> and have something like --used-relations - thanks for the pointer!
>
> Igor
>
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