On Apr 14, 2011, at 1:52 AM, Jukka Rahkonen wrote: > Teemu Koskinen <teemu.koskinen <at> mbnet.fi> writes: > >> >> I converted a few of the biggest lakes in Finland a few years ago to >> coastlines, and they worked fine, until last year some other user converted >> them to multipolygons with natural=water -tags. He also splitted the biggest >> lake (Päijänne) in pieces, which created arbitrary lines across the lakes at >> random where the lake was divided to different polygons. >> >> The biggest lakes in Finland have tens of thousands (or even hundreds of >> thousands) nodes and a LOT of islands, so it's not practical to represent >> them >> as (multi)polygons IMO. > > It is not practical, either, to represent them as coastlines. For example > osm2pgsql is not importing coastlines into PostGIS at all but users must use > the > processed land polygons as shapefiles for rendering these coastline lakes. One > may say it works fine with Mapnik rendering because of this shapefile > workaround. Some could call it as a dirty hack. For example, it gets > complicated > when somebody wants to add tags for the lakes and islands.
FWIW, Dane added a --keep-coastlines flag to recent versions of osm2pgsql. It hasn't fully propagated out to various package managers and things, but it's a big help in these situations. -mike. ---------------------------------------------------------------- michal migurski- m...@stamen.com 415.558.1610 _______________________________________________ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk