[Imports] [Talk-ca] [Import] Ottawa Buildings & Addresses [Statistics Canada project]

Christoph Hormann chris_hormann at gmx.de
Wed Oct 19 23:01:02 UTC 2016


On Wednesday 19 October 2016, James wrote:
> Ok, Christoph now that I am at a proper computer I can address your
> comments:
> [...]

Thanks for the additional information.  Based on this i modify my 
comments, what i am still missing is:

- link to the source data for the buildings
- information on attribute and geometry processing - this refers to how 
the source data is processed to generate the OSM files.  Based on the 
address data this is clearly non-trivial and needs further explanation 
(expansion of abbreviations, conversion of upper case names).
- information on what you actually intend to import - please forgive me 
for not taking the time to scrape every data tile from 
data.osmcanada.ca to determine the extent of the data.

Additional notes:

- the address data is clearly not ready for import in the current form, 
it contains lots of duplicate addresses and positions seem pretty far 
off in some cases, often too far to be properly matched with buildings 
without on-the-ground inspection.

- the building geometries contain various flaws like poor 
orthogonalization, overlaps and impossible geometries like here:

https://www.openstreetmap.org/#map=19/45.32737/-75.70919

and systematic errors like here:

https://www.openstreetmap.org/#map=19/45.32802/-75.71617

- it is unclear how you intend to determine which building geometry is 
more accurate if there is already data in OSM.

> If you are just going to skim over documentation, what is the point
> of creating it?

The purpose is to document the import to allow mappers to look up how 
this particular import is done.  If finding out a specific detail about 
it - like for example to determine how the value of a certain tag is 
determined or which area exactly is affected by the import - requires 
you to read the full text from top to bottom, it does not fulfill this 
purpose that well.

-- 
Christoph Hormann
http://www.imagico.de/



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