[Tagging] tagging the multipolygon model (was landuse and military)

Martin Koppenhoefer dieterdreist at gmail.com
Sat Oct 17 11:56:30 BST 2009


2009/10/17 Pieren <pieren3 at gmail.com>:
> On Sat, Oct 17, 2009 at 10:51 AM, Martin Koppenhoefer
> <dieterdreist at gmail.com> wrote:
>>
>> http://www.openstreetmap.org/?lat=52.4749&lon=13.4858&zoom=14&layers=B000FTF
>>
>
> I see on this place that sometimes the multipolygon relation is used
> for two landuses (forest and recreation_ground) and sometimes not
> (forest and brownfield). Just because Mapnik is rendering them in the
> right order (the forest and the brownfield). But this is tagging for
> current Mapnik styles which is wrong.

why do you think that is was tagging for the renderers? It could be
that the recreation ground is not forest (correct usage of
multipolygon). Didn't find the brownfield, but this would obviously be
an error, as a brownfield is a construction site, where there were
buildings before, so it can IMHO not be a forest.

>> It is possible to have a quarry that became landfill and now is covered by forest.
> As you say, it's not at the same time a quarry, a landfill and a
> forest.

OK, it is no quarry anymore (but still an ex-quarry with some
quarry-characteristics), but it is still a landfill and a forest at
the same time.

> And most of landuse values are exclusive. "military" area is the
> most controversal. A military area can be also overlapping the see.
> That's why the idea to move it from landuse to a boundary is not so
> bad.

like nature-reserves which are not a "landuse" but a legal status
(currently it is in "natural", what leads to similar problems) where
you can find other landuses/landcovers (e.g. sea, lake, forest,
mountains, etc.). In the case of reserves I agree that it shouldn't be
a landuse but neither a natural-key (but a special kind of boundary
with subtags about the kind and level of protection).

cheers,
Martin




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