[Tagging] natural=bay as nodes are evil

moltonel 3x Combo moltonel at gmail.com
Tue Oct 28 16:12:02 UTC 2014

On 27/10/2014, Christoph Hormann <chris_hormann at gmx.de> wrote:
> Since for label rendering you don't really need a polygon there is
> little point in actually generating it in the first place.  But i have
> implemented and used techniques not unlike the algorithm described for
> rendering bay and strait labels, like in
> http://maps.imagico.de/#map=3/80.707/55.862&lang=en&l=dark&r=fj&ui=0

That's actually a very nice rendering. The channels in particular seem
to be oriented very naturally. But when I look at the underlying osm
data (nodes), it is much less clear how those features are oriented. I
feel like the rendering tricked me into thinking "that's it, the
channel is laid out this way" when the actual data says nothing of the

To render a pretty picture, I'd certainly use something like that. To
implement geofencing, area calculations, etc, I'd much rather trust a
human-estimated area.

> The funny thing is the first thing i do for this is reduce all features
> mapped as polygons to a node since the polygon is useless, its outer
> limit is arbitrary and the sides defined by the coastline do not match
> the generalized coastline used to render the map.

I admit I don't fully understand how your algorythm works. I can't
imagine how you reduce everything to nodes and still retain
information about orientation and curves. Can you change your
rendering to display the infered polygons instead of the name ?

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