[Talk-ca] Importing buildings in Canada

Sun Jan 19 01:01:05 UTC 2020

In short, yes. But we should give them a clear option and a clear path 
toward doing it either way - written procedures, provide preprocessing 
scripts/help, etc.

Best,

Nate Wessel, PhD
Planner, Cartographer, Transport Nerd
NateWessel.com <https://www.natewessel.com>

On 2020-01-18 7:37 p.m., john whelan wrote:
> > But also - sorry this is such a long email - we certainly should not 
> be manually doing re-conflation where buildings are very dense (e.g. 
> downtown Toronto) or where they have already been imported extensively 
> (much of the rest of the GTA). The import plan I'm working on for 
> Toronto will take care of most of this automatically by importing only 
> in the sparse gaps between existing OSM buildings. For other parts of 
> Canada, this may not be much of an issue at all - I wouldn't know.
>
> My interpretation is you're happy to leave this call to the local 
> coordinator?  If they have no buildings it's fairly simple if there 
> are buildings already mapped it becomes more complex.
>
> Thanks John
>
> On Sat, 18 Jan 2020 at 19:12, Nate Wessel <bike756 at gmail.com 
> <mailto:bike756 at gmail.com>> wrote:
>
>     Hi all,
>
>     Daniel, thanks for continuing to prod the conversation along :-)
>
>     I guess the point of disagreement here is that I generally don't
>     agree that the ODB buildings are of higher quality than what's
>     already in OSM. The ODB data I've seen is quite messy, and IMO
>     only marginally better than having no data in an area, especially
>     if not properly checked and conflated with surrounding OSM data.
>     People seem to generally disagree with that perspective though, so
>     I'll assume that other areas are better represented by their
>     respective ODB data sources. Central Toronto may just not have
>     been well mapped by the City's GIS dept; it certainly isn't the
>     easiest thing to get right.
>
>     My real worry here is that someone will be carelessly going
>     through an import replacing geometries and will destroy the work
>     of an editor like myself who carefully contributed their time to
>     make a neat and accurate map. I know for certain I've contributed
>     better data in Toronto than what's available from government
>     sources for the same area.
>
>     We must recall that governments produce building footprints in the
>     same way that we do - usually by tracing imagery, and there is
>     little reason to suppose that their data is better or more
>     accurate just because it comes from a seemingly authoritative
>     source. It comes from interns - likely interns with outdated
>     software and low-resolution surveys.
>
>     All that being said, I think my real reluctance to go with the
>     flow here stems from the haste and carelessness of the original
>     importers in the GTA. We're working toward a process that should
>     be very different from theirs though and I probably need to just
>     trust that our process will be calmer, slower, and more
>     thoughtful. If it is, I can get on board.
>
>     But also - sorry this is such a long email - we certainly should
>     not be manually doing re-conflation where buildings are very dense
>     (e.g. downtown Toronto) or where they have already been imported
>     extensively (much of the rest of the GTA). The import plan I'm
>     working on for Toronto will take care of most of this
>     automatically by importing only in the sparse gaps between
>     existing OSM buildings. For other parts of Canada, this may not be
>     much of an issue at all - I wouldn't know.
>
>     Best,
>
>     Nate Wessel, PhD
>     Planner, Cartographer, Transport Nerd
>     NateWessel.com <https://www.natewessel.com>
>
>     On 2020-01-18 5:24 p.m., Daniel @jfd553 wrote:
>>
>>     Bonjour groupe,
>>
>>     Here is a sequential summary of the last exchanges. I inserted
>>     some comments […] within these exchanges description and
>>     summarize what I understand from it at the end.
>>
>>     *Nate*asked not to confuse the process of importing new data with
>>     that of updating/modifying existing OSM data in order to keep
>>     things simple for this import.
>>
>>     *Daniel*(I) responded that importing new data and
>>     updating/modifying existing ones at the same time (when
>>     necessary) is not unusual in OSM [/and would be more efficient/].
>>
>>     *John*replied that importing new data and updating/modify
>>     existing data when required worked quite nicely when importing
>>     Ottawa.
>>
>>     *Nate *explained he believes that the buildings will not be
>>     compared manually since there are hundreds of thousands of them
>>     in OSM for Toronto alone. In other words, he thinks there will be
>>     automated edits, and these edits are not governed by the same
>>     policies as imports. [/This is an important consideration. What
>>     has happened in Ottawa and Toronto so far? Have automatic
>>     processes been used?/]
>>
>>     *Tim*replied that in most cases it might be appropriate to
>>     replace OSM data, as he believes [/as I do for most of the
>>     cases/] that the ODB footprints will be more accurate than
>>     existing buildings. However he considers it is a case-by-case
>>     decision [/then no automation process should be used/].
>>
>>     *John*couldn’t resist digressing toward the “Microsoft buildings
>>     import” but had to bring back the discussion on ODB import after
>>     reactions from *Tim* and *Pierre* (LOL).
>>
>>     I think that, somehow, we could all agree on how the import
>>     should be done:
>>
>>     -Align images on ODB, unless evidence ODB data are ill located.
>>
>>     -Align existing OSM content with the image, *only* if necessary
>>     after aligning the image with ODB.
>>
>>     -Import non-existent buildings in OSM.
>>
>>     -Conflate ODB and OSM buildings, *only* if necessary.
>>
>>     -
>>
>>     To address Nate’s legitimate concerns, we could agree that there
>>     will be *no* automatic changes/conflation of existing buildings.
>>     Having a local import manager and by using the task manager, we
>>     should be able to ensure that there will be no unauthorized
>>     import (i.e. not responding to the above).
>>
>>     Am I too optimistic?
>>
>>     Daniel
>>
>>
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