Hi,
Right, those seem to come from the notorious Corine Landcover import
that was never completed nor reversed even it does have loads of
topological errors. It does bring some colour to the map in about 25% of
the Finnish territory, though. You may know that we do not have very
good alternative sources for land cover imports because 71,6% of the
area of Finland is covered by forests. Therefore our topographic map
database does not even have a class for forests - they are background,
not interesting at all.
I had a look at some polygons and I do not know exactly how they should
be corrected. For example relation
https://www.openstreetmap.org/relation/1481481#map=8/62.740/25.565
It has an inner member https://www.openstreetmap.org/way/104644001 which
somehow looks the same as
https://www.openstreetmap.org/way/104646035
The inner polygon, that is coniferous wood, is a simple polygon with
only outer ring. So as a stand-alone it could carry its own tags. But
because the ring is re-used as a hole of the bigger mixed wood polygon
it should not have tags. Instead the single ring coniferous area should
be changed into a multipolygon relation that has only one member, and
that new relation would get the coniferous tag. Is this correct?
I really much doubt that anybody is interested in correcting the Corine
polygons but people has not been too eager to revert the import either.
Because of the colour, you know. But let's see how other members of the
Finnish community react. I fear also that OSM will never get rid of the
hand-written multipolygon relation system and because the reason for the
trouble will not be fixed you have been forced to start your huge
effort with fixing the broken data
https://wiki.openstreetmap.org/wiki/Area/The_Future_of_Areas. Good luck
for you.
Regards,
-Jukka Rahkonen-
Jochen Topf kirjoitti 2017-04-03 13:25:
Hi!
You might have seen that a few weeks ago I started a huge effort to
clean up broken (multi)polgyons and old-style multipolygon relations
(with tags on ways instead of on the relation) in OSM. You can find out
more about this project on http://area.jochentopf.com/ .
I am writing on this list here, because Finland is a major hotspot for
those multipolygon problems. See these maps:
http://area.jochentopf.com/map/index.html#7/61.923/25.378
http://tools.geofabrik.de/osmi/?view=areas&lon=28.31590&lat=62.06443&zoom=8
This is probably due to some imported data. Is anybody here interested
in this topic? How can we move this forward?
Jochen
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