[OSM-talk] Ground truth for non-physical objects

[Andy Townsend]

On 13/12/2018 10:40, Tomas Straupis wrote:
>
>    What is "ground" in this term for non physical objects:
>    1. Physical place which could have some traces of an actual object.
>    2. Ground where non-physical objects actually live - documents.
>

The whole point of the "verifiability" and "ground truth" principles is 
so as _not_ to have to rely on documents.  If I want to find the border 
between Ireland and Northern Ireland, for example, I might not (yet) 
find anything stopping me driving through but I will see something along 
the lines of "speed limits now in mph" or the reverse.  Reliance on 
non-physical objects is only necessary where you really can't see 
something on the ground (such as the border between lower and upper 
Rossnowlagh at https://www.openstreetmap.org/#map=13/54.5702/-8.2369 ).  
The fact that we can't get some boundaries from an on the ground survey 
doesn't mean that we have to rely on "documents" for all of them, and 
for a good reason - "documents" often contradict each other, even from 
the same organisation.

Best Regards,

Andy