[Tagging] natural=bay as nodes are evil

moltonel 3x Combo moltonel at gmail.com
Mon Oct 27 09:44:01 UTC 2014

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. 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 ? The
situation is even harder to gauge when there is no imagery to give a
sense of scale. I'm sure most mappers just put the node where they'd
put the label (blissfully ignoring scales and projections).
Bays-as-polygons bring real value by sorting out this mess.

> Specific arguments aside - i am not sure if you realize the consequences
> it would have if subareas of oceans would generally be mapped as
> polygons - large bays usually contain smaller bays and are parts of a
> sea and there might be a strait between an island and the coast within
> that bay.  If you want to edit the coastline in such situation you
> would end up having to deal with a handful of convoluted multipolygon
> relations, some of them of colossal size.  Properly editing coastlines
> is difficult for beginners in the first place.  This would make it
> borderline impossible.

Some coastline ways would belong to more relations, so what ? They
already usually belong to 3-4 administrative boundary relations,
adding 1-2 bays won't make a big difference. I'm tired of the
"multipolygons are complicated, avoid them" argument, it should be
"multipolygons are complicated, make them simpler".

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