Hi multipolygon masters, How would you tag some island-rich Finnish lakes, for the one here: http://www.openstreetmap.org/?lat=62.1747&lon=28.6278&zoom=13&layers=B000FTF
Currently big lakes in Finland have been tagged as coastlines which is a good workaround and looks correct in slippy maps. However, it is not right, because they are not seas but just lakes. Additional drawback is that these fake-seas are hard to use for non-OSM purposes because they won't get imported by osm2pgsql. Cloudmade shapefiles are also very messy, islands can be water and water dry land even if coastline tagging and ring directions are OK. But tagging big lakes in some other way is problematic because the outer rings tend to be rather large and there can be quite a many holes in the lake polygons. Such an OSM multipolygon relation could be a bit painful to edit afterwards. And actually each inner polygon should be an own island/islet polygon as well with own tags, at least a name tag. The biggest lake polygon in the data from National Land Survey of Finland has more than 280000 vertices. Osm data is not as accurate and has less nodes, but even OSM lakes can be quite complicated. By the way, why do we call all polygons having holes as multipolygons, even if they have only one outer ring? But of course they can be considered as simple multipolygons. -Jukka Rahkkonen- _______________________________________________ Tagging mailing list Tagging@openstreetmap.org http://lists.openstreetmap.org/listinfo/tagging
