[Tagging] natural=bay as nodes are evil

Mateusz Konieczny matkoniecz at gmail.com
Sun Oct 26 18:53:51 UTC 2014


> Doable for sure but an awfully bad idea, mapping bays as areas would
> mean two features for the same object (coastline polygon and bay area).

Coastline polygon and bay area is not the same object. Yes, part of border
is
shared - it is nothing wrong. Also it is possible to use for example
multipolygons.

> Furthermore the outer edge of a bay, i.e. the edge that is not
> coastline is usually not well defined and would require an arbitrary
> cutoff.

Yes, cutoff is unfortunately quite arbitrary. But node placement is
completely arbitrary - and lacks important information.


2014-10-26 19:00 GMT+01:00 Christoph Hormann <chris_hormann at gmx.de>:

> On Sunday 26 October 2014, Mateusz Konieczny wrote:
> > Please, try mapping bays as areas - not as nodes.
> >
> > It is really rare to see it done this way - but it is doable, see
> > http://overpass-turbo.eu/s/5CQ
>
> Doable for sure but an awfully bad idea, mapping bays as areas would
> mean two features for the same object (coastline polygon and bay area).
> Furthermore the outer edge of a bay, i.e. the edge that is not
> coastline is usually not well defined and would require an arbitrary
> cutoff.
>
> Maintaining bay polygons would be an awful mess, they would end up
> frequently being broken.  And there is no gain at all in terms of
> substantial information in the database compared to nodes (since the
> coastline is already mapped and the non-coastline edge is arbitrary).
>
> The reason you would prefer areas is probably simply that this would
> make it easier for to use in rendering - but making life more difficult
> for the mapper just to make it easier for the renderer is not a good
> idea.  Based on the coastlines and the bay nodes you can quite easily
> generate approximate bay polygons that can be used for the purpose of
> labeling for example (yes, even for the Paulsdorfer Bucht).
>
> This argument by the way was already made in a slightly different
> context in
>
> https://github.com/gravitystorm/openstreetmap-carto/issues/804
>
> --
> Christoph Hormann
> http://www.imagico.de/
>
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>
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