[Tagging] one feature one element

Tobias Knerr osm at tobias-knerr.de
Fri Jul 5 21:00:37 UTC 2019


On 05.07.19 11:57, Mariusz wrote:
> On 05.07.2019 07:05, Joseph Eisenberg wrote:
>> [Examples of bad situations:] "An area object representing a
>> single-use building with a point object inside it. Move the tags to
>> the area object and delete the point."
> 
> This is common and widly accepted practice. Don't try to change mappers
> behaviour by editing wiki.

It's true that shop tags on building outlines are a common practice.
However, POI nodes inside buildings are likewise common. So I believe it
was a good idea for Joseph to remove this statement. It did present a
widely accepted practice as a "bad situation" in need of fixing, after all.

> It is fine to map multiple real objects with one osm element

It'd say it's ok as a shortcut during initial mapping, but it is far
from ideal. As soon as you want to add tags which only apply to one of
the features (you mentioned "start_date" or "operator" as two examples,
but of course there are more), using separate elements becomes necessary.

> Nothing new, this problem already existed with roads and bridges and was
> fixed by putting bridge name into bridge:name tag.

It wasn't properly fixed until the introduction of man_made=bridge –
that is, a separate OSM element for the bridge.

The bridge:name tag was only a band-aid for a single symptom of a deeper
issue. It did little to address the other symptoms, such as multiple
roads running across the same bridge, and tags other than name.

Tobias



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