[OSM-talk] Fixing broken multipolygons

Christoph Hormann chris_hormann at gmx.de
Fri Feb 17 10:11:12 UTC 2017

On Friday 17 February 2017, Andreas Vilén wrote:
> We are aware of the Corine import problems and have discussed them
> locally at least in Sweden. Our community is very loose with not much
> activity in mailing lists or other media, but so far consensus has
> been not to remove Corine if it's not replaced by improved data.
> I have done some cleanup myself mostly around Kalmar, but in the huge
> Northern parts of the country it seems unmanagable. Some users have
> made good progress in the Bergslagen area though.

Well - the question you should probably ask yourselves is if this data 
is of any help when you map in these areas.  I find it doubtful that it 
is and areas like here:


support this impression.  IMO it would be a good idea to concentrate on 
what you gain and not too much look at what you loose.

If there are worries in the local community about how to efficiently map 
large wooded areas there are other methods that would be much better 
suited.  Forests can be positively detected on multispectral imagery 
with good reliability - in contrast to land cover classification data 
sets like Corine which essentially only specify the least unlikely of a 
fixed set of classes.  Producing a conservative data set this way (i.e. 
one that only includes area which are clearly wooded), splitting this 
into reasonably small chunks and providing this to mappers to avoid the 
need for a lot of large scale tracing work seems a much more productive 
way and much more compatible with normal manual mapping in OSM.

Christoph Hormann

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