[Tagging] Another multipolygon question

Kevin Kenny kevin.b.kenny at gmail.com
Sat Oct 20 14:49:57 UTC 2018

Not only legitimate,  but recommended!

If you haven't stumbled on it yet, another useful procedure is to map areas
of landuse use or landcover by drawing each border only once, and having
each area be a multipolygon with the shared border way as a member. With
that approach there's no need to retrace an irregular boundary. You just
add it to the multipolygon on either side.

For an example, look at West Point.
https://www.openstreetmap.org/relation/175474 and how the shared ways with
the parks, cemeteries, golf courses, and so on are handled. It means that
even simple areas like https://www.openstreetmap.org/relation/7084917
become multipolygons, but it ensures that the boundaries all stay
consistent, because you need to map each one only once.

On Sat, Oct 20, 2018, 06:22 Martin Koppenhoefer <dieterdreist at gmail.com>

> sent from a phone
> > On 20. Oct 2018, at 11:38, Dave Swarthout <daveswarthout at gmail.com>
> wrote:
> >
> > But yesterday I tried something new, new for me anyway, and that was to
> create a single-member multipolygon from the coastline way and then tag the
> resultant relation with natural=wood in order to reduce the number of nodes
> used. I was pleased that JOSM didn't complain and that the island seemed to
> render okay but I'm not sure this is a legitimate procedure
> I also do this, for example if there’s a fence but I also want to tag the
> area it delimits. Or for buildings and things that are there, in some cases.
> Cheers, Martin
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