[Imports] Ongoing Canadian building import needs to be stopped, possibly reverted

Nate Wessel bike756 at gmail.com
Thu Jan 17 15:28:54 UTC 2019

I just learned yesterday of a very large import of buildings across 
Canada that seems to have been posted to this list in November without 
getting much of a response. I remember seeing the email about it at the 
time, and as there was substantial reference to an import in Ottawa, I 
thought the import was limited to that city and failed to read the 
actual details of the proposal. This appears to be an import of building 
footprints across ALL MAJOR CANADIAN CITIES.



This is being imported NOW, very quickly, and the data I've seen in 
Toronto is of dubious quality at best. Given the speed with which this 
has taken place and the lack of clear discussion about what exactly the 
import is, what exactly it covers, I would like to see this import 
effort halted immediately if not reverted.

My concerns are as follows:

1. I'm a very active mapper living and editing in Toronto and subscribed 
to the relevant lists and slack channels, yet I only just learned of 
this when the buildings encroached on my own neighborhood. I imagine 
many others also missed the notice and have not had any chance to review 
the plan.

2. There are countless examples of truly terrible data quality, weird 
footprints, overlapping buildings, wildly unsimplified geometries, etc. 
These issues clearly fail in a simple JOSM validation, which indicated 
that no validation is happening before upload.

3. The data is being imported in extremely large chunks, (see the 
tasking manager grid for Ontario: 
http://tasks.osmcanada.ca/project/145), much larger I think than any one 
person could validate or review in a single sitting. There are more than 
ten thousand buildings in some of these grid cells. As changesets are 
limited to 10k objects, including nodes, it is extremely difficult to 
see what data was there before these changes, as each task involves 
multiple essentially simultaneous changesets.

4. The approach seems to be import first, validate second (if ever?).

5. The wiki plan gives no clear description of the plan for integrating 
new data with old. In places where there used to be user-contributed 
buildings, I now see buildings from this import covering or replacing 
those buildings with no remaining way history. I don't think I need to 
say that this is completely unacceptable.

What are the options on the table here? There has been a truly massive 
amount of data imported in the last couple of weeks. I'd love to wind 
back time and criticize the living hell out of this plan before it 
started, but that's not where we're at. What can be done?


Nate Wessel
Jack of all trades, Master of Geography, PhD candidate in Urban Planning
NateWessel.com <http://natewessel.com>

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