[OSM-dev] Looking for guidance on interpreting multipolygon relations

[Martijn van Oosterhout]

On 11/3/07, Jon Burgess <jburgess777 at googlemail.com> wrote:
> When I wrote the Mapnik/osm2pgsql code to handle this I think decided to
> use an aggregate on all the tags on all the ways in the multipolygon. At
> the time it first wants to know what tags to use the code unfortunately
> has no idea which way is the outer one (since the information is not in
> the relation). It works out which ring is the outer one by sorting them
> by the enclosed area. I could probably make it re-evaluate the tags
> after it has determined which way is the outer ring.

In retrospect I guess this was short-sighted. The relation should
probably have included information about positive and negative areas,
or inner/outer rings. But it's a little late to fix now :)

Have a nice day,
-- 
Martijn van Oosterhout <kleptog at gmail.com> http://svana.org/kleptog/