[OSM-talk] Tagging of areas with holes

[Dave Stubbs]

On 30/10/2007, David Groom <reviews at pacific-rim.net> wrote:
> Just a couple of questions relating to areas with holes and multipolygon
> relations.
>
> Firstly do mapnik and osmarender currently support the rendering of this
> type of relation?
>
> Secondly how exactly is this tagged.  I understand ( I think ) how to
> actually create the relation, but am unsure what needs to be tagged.  Do the
> individual ways need to be tagged as landuse=forest; or is it the
> multipolygon relationship which needs to be tagged as landuse=forest; or do
> the individual ways and the multipolygon relationship need to be tagged as
> landuse = forest?

Mapnik supports it.

I was looking through the import script for that the other day. What
it appears to do is collect together all the tags for the ways that
are part of the multipolygon, and render the area using those tags.

So you'd need to add the landuse tags to the ways that make up the
polygon, but the relation just needs the type=multipolygon.

As example go look at the tagging for buckingham palace...a building
with a hole:
Map: http://www.openstreetmap.org/?lat=51.50057&lon=-0.14069&zoom=16&layers=B0F
API: http://www.openstreetmap.org/api/0.5/relation/245/full

It does actually seem to work on osmarender too.