[Tagging] Tagging of topographic areas with a name

Yuri D'Elia wavexx at users.sourceforge.net
Tue Aug 6 15:28:33 UTC 2013

On 08/06/2013 04:27 PM, Yuri D'Elia wrote:
> Might still be problematic. A forest, sometime lakes, rivers for sure
> and many other big polygons will cross the boundary of the mountain group.
> It's kind of unfortunate, because a mountain group will span across
> italian regions and include parts of several valleys. Of course,
> likewise, valleys have the same problem. It's not a hierarchical
> information either.
> It's really a topographical information, and I feel like tagging objects
> within or using relations might be really problematic. Just imagine what
> kind of "spotty" tagging would you have for big mountain groups. Huts
> and peaks would definitely not be enough for a decent boundary.
> But also drawing big areas is kind of ugly :(.
> Fortunately, the boundaries of the area are not important in themselves.
> Nobody renders valley or mountain group borders. But we *do* use such
> boundaries for name placement.
> I'm thorn.

I'm attaching a crude osm file I edited quickly to demonstrate the problem.

Valleys usually end exactly at the mountain ridges. Valleys also end at
the border of a mountain region or at the border of another valley.
Between valleys, the border is purely arbitrary (it's mostly determined
by geographic properties).

In the alps I would expect a mosaic which is essentially totally filled
with valleys. A relation would be great to re-use existing geometry, but
some new boundary type will also be needed to mark the end where's no
additional geometry can be reused.

I also created two (inexact) mountain groups. Mountain groups actually
form a complimentary mosaic, as you see in the file. A mountain group
would start at the middle of a valley (which I didn't do in the example,
but you get the point) and end at another one. The only exception might
be where you have very large valleys, like the "Val D'Adige", where the
group doesn't start in the middle exactly (but doing so wouldn't exactly
be "wrong" either). For mountain groups I do not see any existing
geometry that could be reused, except occasionally for the nodes where
the valleys cross. A new boundary type is definitely needed, and the
edges could be shared with a "mountain group" relation.

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