[Talk-us] buggy buildings in Maryland

[Frederik Ramm]

Hi,

over the last 2 years, DWG has had a three different complaints about a
buggy building import that has been run on and off by the user
"annapolissailor".

The import was problematic in many ways, most obviously because huge
batches of un-used nodes were uploaded and later it was attempted to
connect them, which sometimes failed, leaving lots of un-used nodes in
the database; also, almost all buildings are over-noded, taking 10 or
more nodes for a simple rectangular building (eg
https://www.openstreetmap.org/way/435663194). Buildings that were in the
area before have been deleted outright, and the data source and legal
situation is unclear (many buildings are much too precise to have come
from aerial imagery).

(Needless to say, had the import been discussed up front as is
customary, all these issues could have been avoided.)

I have tried to work with the importer but they seem to be ultimately
unable or unwilling to fix the problems even though they did seem to
understand the issue at some point
(https://www.openstreetmap.org/user_blocks/1587). They asked me a couple
of times to "hold off reverting data until next steps are discussed on
the imports list" but never followed up on the promise. They claimed to
have spent hundreds of hours on the JOSM validator improving problems
they had introduced.

I am at the moment deleting about 70,000 untagged and un-used nodes that
have been left over from this import, which is the uncontroversial part.

The total amount of buildings created and still visible is 177,151, with
a total of 1,980,336 nodes, in the general area "East of Washington DC,
South of Baltimore, North of Chesapeake Beach".

I think these buildings need to be deleted too, given their technical
(over-noding) and legal (we don't know where the data came from and what
license it is under) issues.

However, given how much work the mapper claims to have invested in this,
I wonder if there's maybe a way to salvage the data. That would first
require us to clear up the legal situation, and if it turns out the
source is legal, then we'd have to go about killing the extra nodes in
buildings.

I'm basically looking for volunteers here. Other mappers have tried to
discuss the issue with the mapper himself and never got far either, but
of course if someone wanted to try and enlist annapolissailor's support,
fair enough (perhaps agree here on the list who's doing it though, so
that we don't have 10 people spamming him...)

I have prepared a file that contains all the buildings in question:

http://www.remote.org/frederik/tmp/annapolis.osm.gz

Bye
Frederik

-- 
Frederik Ramm  ##  eMail frederik at remote.org  ##  N49°00'09" E008°23'33"