[Tagging] place nodes for continents?

Christoph Hormann osm at imagico.de
Tue Aug 7 09:31:09 UTC 2018

On Tuesday 07 August 2018, Frederik Ramm wrote:
> How is a continent node verifiable, especially with regards to its
> position? What is our plan if two people should start edit-warring
> about whether the continent node should be at 51.0000002,
> -109.0000002 (as it currently is), or rather at 51,-109 or at
> 50,-108?
> Representing a tree or a pothole with a node is not exact either, but
> it's more or less within the accuracy of our available measurement
> devices. Representing a city with a node is much less accurate, but
> people seem to agree for most cities, placing the city node in the
> heart of the old city, or where the city hall is, or some such.
> Do we really want to approximate whole continents with a point, and
> if we do, where is that point to be placed?

If this is going where i think this is going (i.e. creating continental 
multipolygons) then hell no, please stay with the nodes.

My take on node mapping of large, primarily coastline delimited features 
can be found in:


Together with the coastline data place nodes for oceans and continents 
contain most of the data necessary for determining location and extend 
of the features in question on a level of accuracy necessary for 
cartographic applications.  And the tagging of the nodes is largely 
verifiable data.

A word regarding tolerance of coordinates and the implication that they 
should be or have to be within the tolerance of measuring devices - i 
don't think this is or should be the case.  The point of verifiability 
in OSM is not a tolerance threshold, it is if multiple independent 
determinations converge to a single data point.  Standard deviation of 
that might be 50m or it might be 500km.  If you ask a thousand mappers 
to position a place node for Africa and 90 percent of them place it in 
or around the Central African Republic you have a verifiable mapping 

If this is always the case for place=continent at the moment i am not 
sure.  Documentation of the tag does not provide any help.  At least 
the Oceania node seems more like an arbitrary labeling node - and the 
classification and definition of Oceania as a continent is quite 
culture specific as well.

Christoph Hormann

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