[Tagging] How to put a name tag on an area with more than one type?

Anders Torger anders at torger.se
Sat Dec 12 11:23:29 UTC 2020


Sorry, I realize I have a followup question. Is this really the right 
way?

There's a difference from the Rhine example. With rivers all the 
separate parts are tied together with a parent relation of the type 
waterway, and the parts have roles like "main_stream".

In the wetland case as described, there is no parent relation at all. 
The only thing that ties them together is implicitly by sharing borders 
and having the same name tag. It seems to me that an "official" way to 
edit should tie them together with a parent relation.

The logical way would be a parent relation with type=wetland (and 
actually have the name only there, but no renderer today understands 
that, it needs to be on the separate parts as well). What should the 
roles be? The most logical way would be to leave role field empty. To 
summarize:

Suggested method of how to name a wetland that has more than one 
sub-type:

* Prerequisite: each sub-type (marsh, bog etc) is a polygon (or 
multipolygon if required,
   for example if there's an inner water or forest) which shares segments 
with the
   neighboring sub-type, ie the wetland is a single entity.
* Put the name on each part, same for all
* Create a relation with type=wetland (no sub-type) and include all 
parts with role
   field empty, also name this relation with the same name (although no 
current
   renderer will care)

What do you think about this way? JOSM thinks it's fine at least, I get 
no warnings :-).

(Note that there's another case that can be solved with just a single 
multipolygon, when there's a single sub-type but the parts are 
separated, so each part can be an outer, this is also (quite) common, 
although more common for waters and islands than wetlands. The special 
thing with the discussed case is that it's a single entity all parts 
bordering to the next)

On 2020-12-11 20:55, Anders Torger wrote:
> Thanks I'll do it this way then, this actually works and even gets
> rendered, although with OSM-Carto it becomes a name tag in each
> separate part so not exactly beautiful, but the data is there.
> 
> /Anders
> 
> On 2020-12-11 18:07, Christoph Hormann wrote:
>>> Anders Torger <anders at torger.se> hat am 11.12.2020 17:07 geschrieben:
>>> 
>>> The least bad way I've come up with is to just name all polygons
>>> belonging to the same wetlands the same,
>> 
>> That is widely considered to be the correct way.  It is established
>> practice that mapping things like forest, wetland, farmland etc. can
>> be split to differentiate tagging (like leaf_type, wetland type, crop
>> etc.).  The name tag is then applied to all components.  Same as for
>> waterways or roads where you can also split and apply the name to the
>> components.
>> 
>> This also matches the general concept in OSM that names are typically
>> local properties and only locally verifiable.  The Rhine river is
>> called Rhein in Koblenz but Rhin in Strasbourg and Rijn in Rotterdam.
> 
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