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 <[email protected]
<mailto:[email protected]>> 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 It comes from interns - likely interns with outdated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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