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 <no...@bwl.uni-hildesheim.de> > An: "dev@openstreetmap.org" <dev@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.podols...@vwi-stuttgart.de] > Sent: 06 August 2011 17:44 > To: dev@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 > > _______________________________________________ > dev mailing list > dev@openstreetmap.org > http://lists.openstreetmap.org/listinfo/dev > > _______________________________________________ > dev mailing list > dev@openstreetmap.org > http://lists.openstreetmap.org/listinfo/dev _______________________________________________ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
