[OSM-talk] Czech republic not in Europe?

Paul Houle paul at ontology2.com
Sat Jul 2 14:54:50 BST 2011


  On 7/2/2011 9:00 AM, Jakub wrote:
> According to this reation: 
> http://www.openstreetmap.org/browse/relation/7888 Czech republic (and 
> many more countres) is not in Europe. Or am I missing something?
>
     I don't see Germany or France either!

     I tried to build a geospatial hierarchy out of OSM about a year ago 
and gave up on it because the quality of data wasn't good.  I ended up 
using Yahoo's GeoPlanet because at least it was (sorta) consistent,  
even if the shapes look terrible.

     For instance,  one problem is that there's no constraint that 
forces country outlines to be closed.  For instance,  the boundary of 
South Africa contained only the coastline.  This kind of problem 
persists in OSM because OSM's "quality control" mechanism is feedback 
that come from users who are interested in maps.  If you're just drawing 
maps,  the boundaries of the countries to the north of South Africa will 
cause the boundary to be properly drawn.  Nobody sees or cares that 
there's something wrong.

     On the other hand,  if you're interested in doing spatial reasoning 
("Is point A inside South Africa?") the non-closed country boundary is 
absolutely useless.

     I guess the answer is somebody who wants good data in this 
department ought to fix it,  but it's a big job,  and since GeoPlanet is 
"good enough" for now,  I haven't been motivated to try to do anything 
about it.



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