2012/12/5 Serge Wroclawski <[email protected]>: > On Tue, Dec 4, 2012 at 8:44 PM, Jeff Meyer <[email protected]> wrote: >> - For relations: do NOT read the wiki & HELL YES read the wiki > Relations are a complex topic. They're generally loved by those who > like to talk in theory but not in practice. > The problem is they're very hard to work with.
the thing with relations is, they are completely universal, you can model any kind of relation between nodes, ways and other relations, but naturally only a few concepts are generally evaluated (and used in mapping). Some relations are established though, and those get also evaluated for a wider group of maps, are supported in current tools and libs like osmium or osm2pgsql or for routing, and it's worth mentioning this. These are - "multipolygon" and "boundary" relations (basically the same) - "route" relations - turn "restriction" relations to see more types and actual usage statistics have a look at taginfo: http://taginfo.openstreetmap.org/keys/type#values (there is public_transport, site, street and associatedStreet also in significant numbers, but AFAIK they get less often evaluated). Note that not all objects with a "type"-tag are relations. cheers, Martin _______________________________________________ talk mailing list [email protected] http://lists.openstreetmap.org/listinfo/talk
