[Tagging] Stop the large feature madness (was: Tag for a plateau or tableland?)

Christoph Hormann osm at imagico.de
Wed Apr 17 11:52:53 UTC 2019

On Wednesday 17 April 2019, Frederik Ramm wrote:
> [...]
> The way OSM usually works is someone stumbles over something in
> reality, with a discernible name or property, and adds it to OSM. We
> are, first and foremost, surveyors.
> The larger a feature becomes, the less suitable OSM is for mapping
> it. And in the case of the several large-scale objects I have
> mentioned, most contributors don't even have surveying in mind, but
> just writing down existing conventions.

Indeed.  We should always keep in mind that OSM is fundamentally about 
collecting local knowledge of the geography.  'local' is key here.  If 
you try to map some geometry for the Altiplano or the Tibet Plateau 
that is not local knowledge.

As a rule of thumb i'd say something that can at least coarsely be 
surveyed on the ground by a single mapper during a single day is 
usually suitable to be mapped as a distinct named feature, provided it 
is otherwise verifiable of course.  For larger things mapping should 
focus on locally mapping locally surveyable constituent parts or 
aspects of the feature but i would be very careful with creating 
features for them as a whole because this very often drifts from the 
OSM idea of mapping local knowledge to a Wikipedia-like recording of 
social conventions.

Some of the things Joseph mentioned (like buttes) are certainly mappable 
in OSM under this rule - but i'd suggest creating specific well defined 
tags with a precise and tight definition for them and not a generic tag 
for any elevated region.

In any case i think the most valuable thing to map of any of such is the 
constituent elements and aspects of it like natural=cliff, 
natural=arete, natural=peak, natural=bare_rock, natural=scree etc.

Christoph Hormann

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