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

Christoph Hormann osm at imagico.de
Fri Apr 19 10:26:42 UTC 2019

On Friday 19 April 2019, Graeme Fitzpatrick wrote:
> > But as already hinted i am not sure if the Drake Passage is
> > something i would consider mappable in OSM based on local
> > knowledge.
> But, without wishing to sound facetious, how do we then have
> coastlines for Eurasia, Greenland & Antarctica mapped?
> *Nobody* has "local knowledge" of the full coastline of any of them,
> & for Greenland & Antarctica, what is mapped - the ice cap, which is
> constantly moving, or the deep underlying rock? Should we erase them
> off the map as they're not "verifiable"?

It is interesting that the idea that large size abstract concepts 
projected onto arbitrarily delineated parts of the physical geography  
by cultural convention like bays, peninsulas, linear rivers and 
plateaus might not be suitable for being recorded in OSM is by several 
people in this discussion reinterpreted as - and i am only slightly 
exaggerating here - that mappers may only record things after they have 
personally touched every centimeter of them.

That does not make much sense of course.  Physical presence near a 
certain geographic setting can help you immensely to acquire local 
knowledge of it but it is neither a guarantee for doing so nor a 
prerequisite for mapping things.  And as said in the past verifiability 
based on local knowledge does not require everything in the database to 
be independently verified by several mappers with local knowledge.  It 
just requires the possibility to do so.

When mapping the coastline of Greenland or the Antarctic you have 
several independently recorded image sources available (not what you 
find in Bing & co. though - that is all the same 20 year old stuff) 
where you can localize the coastline on and there are also quite a few 
people mapping in OSM who have visited these areas.  This is definitely 
not a problem of lack of local verifiability.  In cases of doubt (which 
there might be, in particular if sea ice is present on images) we can 
look together at the images to resolve the situation or we can consult 
people with local knowledge.

Christoph Hormann

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