[Tagging] natural=bay as nodes are evil

Richard Z. ricoz.osm at gmail.com
Mon Oct 27 11:13:40 UTC 2014

On Mon, Oct 27, 2014 at 10:44:01AM +0100, moltonel 3x Combo wrote:
> On 26/10/2014, Christoph Hormann <chris_hormann at gmx.de> wrote:
> > I don't see what information is missing and cannot be easily determined
> > automatically with a properly placed node that is contained in an
> > area - except for the outer edge of course, which is usually
> > ill-defined though as you said yourself.
> >
> > If you think about it a bit and do not try to place the node where you
> > would place the label (which depends on the map projection anyway)
> > properly placing a node for a bay is usually quite simple.  The most
> > difficult are long, fjord-like bays where a way along them would be
> > more appropriate.
> I'm really curious what your method to figure out the bay area from
> the node is, because even as a human I find that most bay nodes can
> lead to many different interpretations.

you don't. Al that the node says is "somewhere there is a bay called

> A computer algorythm would
> probably get it wrong most of the time. Think back to the "bays within
> bays" situation. How far along the coast do this bay extend ? Are
> those two nearby nodes separate bays or overlapping ones ? 

Most of the time there is very little agreement or hard data about the 
extents and hierarchy of bay naming. Sources from different countries will
make different subdivisions. Great fun with multipolygons and even with 
perfect tagging and computer algorithm we get approximate results at best.


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