[Talk-ca] City of Ottawa imported buildings & addresses
aj at ajashton.ca
Mon Oct 17 16:59:51 UTC 2016
I haven't seen any substantial discussion about the Ottawa buildings &
addresses import anywhere. I did see the thread a number of weeks back,
"Crowdsourcing buildings with Statistics Canada," but I didn't see
anything discussed that sounds like the planning of a mass import. The
wiki page linked from the discussion  is completely empty. From a
changeset discussion I was pointed to another section of the wiki 
which again has few details and does not sound like an import
("...inviting contributors to crowdsource information on buildings").
What has actually happened is most (or all?) of the existing buildings
in Ottawa were deleted, and then replaced by imported data. For example
changeset 42699159  deleted hundreds of buildings and addresses I had
mapped in my former home of Stittsville. Changeset 42699460  replaced
everything with City of Ottawa data.
The quality of the imported shapes seems fine and I have nothing against
building imports in principle. I just wish existing data could have been
updated or left alone - I don't see a substantial difference between
what I had traced from Bing and the import except for an offset of
perhaps a few meters. Although I saw someone noted on IRC that in
several cases existing properties such as building:levels tags were
lost; this is more concerning.
In addition to building footprints, addresses are also being imported.
This data is a little more problematic and the importers seem to be
taking a "import now, fix later" approach. Example: changeset 42633517
 added over 20 thousand address nodes that were clearly not
quality-checked. Addresses are being imported as points when they could
be attached to buildings, and sometimes address points are doubled,
tripled, or even quadrupled .
: Eg this area:
Could the organizers of this import point me to any further mailing list
discussions or wiki pages I might have missed? Can we talk about why the
clearcut approach to existing data was taken, and why the address data
was not cleaned up *before* import?
(The changesets I linked to may make it look like I am specifically
calling out user LogicalViolinist, but the import was a group effort by
a number of users. LogicalViolinist just happens to have covered the
part of Ottawa I am most familiar with.)
aj at ajashton.ca
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