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<p>Hi Daniel, <br>
</p>
<p>Thank you for all the work you've put into this. I'd like to
offer a couple suggestions and/or clarifications for your proposed
import process, overview though it is. <br>
</p>
<p>First, I think it is very important that a tasking manager is set
up on a city/by city basis only, and that only AFTER consensus is
achieved that the import should proceed in that area. I would
really like to avoid seeing the massive nationwide tasking that
was set up the first time around. We should be making it hard for
people to go rogue in regions where consensus for an import
doesn't (yet) exist. <br>
</p>
<p>Related to this, though important enough to be a second point in
it's own right, the tasking squares need to be small enough that a
single user can manage them and inspect every single building in a
task. The first round of import used task squares that were
massive, and which couldn't be divided any further past a certain
point. Even in rural areas, it is likely inappropriate to import
areas larger than 1km^2. In central Toronto it would be (and was)
idiotic. An import that doesn't take local scale into account
shouldn't proceed. "Too big to load into JOSM" is about 100x too
big to import in my opinion and is not a good enough benchmark for
import batch sizing. <br>
</p>
<p>That is, each import needs to be local, and not just in a
superficial sense. <br>
</p>
<p>I'll also add that the issue of conflation doesn't seem to have
been worked out yet except to note that it is an issue. What will
we do with the millions of buildings which will substantially
overlap/duplicate existing buildings or imports? This needs to be
worked out in detail before anything starts up again. <br>
</p>
<p>And what needs to be done about already existing low quality
imports? It's good to acknowledge their existence, but what will
be done about them? We've set up a task to clean up some of the
mess in Toronto ( <a class="moz-txt-link-freetext" href="http://tasks.osmcanada.ca/project/168">http://tasks.osmcanada.ca/project/168</a> ) but this
is only the tip of the iceberg. <br>
</p>
<p>Again, I thank everyone for their time and effort on this - we
can get this done if we go slow and do it right :-)</p>
<p>Best,<br>
</p>
<div class="moz-signature">
<p> Nate Wessel<small>, PhD<br>
Planner, Cartographer, Transport Nerd<br>
<a href="https://www.natewessel.com"
style="text-decoration:none;">NateWessel.com</a></small>
</p>
</div>
<div class="moz-cite-prefix">On 2020-01-03 3:40 p.m., Daniel @jfd553
wrote:<br>
</div>
<blockquote type="cite"
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<p class="MsoNormal"
style="margin-bottom:10.0pt;line-height:115%"><span
lang="FR-CA">Bonjour groupe, mes excuses pour ce très long
courriel !-)<o:p></o:p></span></p>
<p class="MsoNormal" style="line-height:115%">I have reviewed
everything that has been written on the ODB import (aka Canada
Building Import) in Talk-ca and the wiki. I proposed changes
to some wiki pages (via talk tabs) to ease the discussions
about this import and the following. Now, in order to restart
the import, here are some thoughts and a proposal on how to
proceed to complete the task.<o:p></o:p></p>
<p class="MsoNormal" style="line-height:115%"><o:p> </o:p></p>
<p class="MsoNormal" style="line-height:115%"><b><span
style="font-size:14.0pt;line-height:115%">1. Issues with
the ODB Data Import<o:p></o:p></span></b></p>
<p class="MsoNormal"
style="margin-bottom:10.0pt;line-height:115%">Many concerns
were raised about the import. One major concern was to obtain
local communities’ buy-in in the Canadian context. Another
concern was to improve the quality of the data prior the
import. The following paragraphs intend to clear most of these
concerns.<o:p></o:p></p>
<p class="MsoNormal" style="line-height:115%"><b>1.1. Which data
import project?<o:p></o:p></b></p>
<p class="MsoNormal"
style="margin-bottom:10.0pt;line-height:115%">According to the
import guidelines (steps 3 & 4), a data import explicitly
refers to a single data source (ODB in our case). Discussions
about the availability and quality of Microsoft or ESRI data,
while interesting, are not relevant as they should be dealt
with as other import projects.<o:p></o:p></p>
<p class="MsoNormal" style="line-height:115%"><b>1.2. What has
been imported so far?<o:p></o:p></b></p>
<p class="MsoNormal"
style="margin-bottom:10.0pt;line-height:115%">According to
what I found [1], the ODB import is completed for 21
municipalities. These imports seem to have kept OSM content’s
history, at least for the samples checked, but many problems
were found. In some case, the imports brought swimming pools
in OSM because they were included in the dataset (e.g.
Moncton). In other cases, importing buildings with accurate
locations (XY) over content mapped from less accurate imagery
resulted in buildings that now overlap the street network
(e.g. Squamish). It means that all these 21 imports need to be
carefully re-examined and corrected as required.
<o:p></o:p></p>
<p class="MsoNormal"
style="margin-bottom:10.0pt;line-height:115%">For 12 other
municipalities, the import is partial, either suspended as
requested, or because previous imports had already provided
most of the buildings (often from the same municipal
provider). That said the import will definitely improve OSM
accuracy and completeness if done properly.<o:p></o:p></p>
<p class="MsoNormal" style="line-height:115%"><b><span
style="font-size:14.0pt;line-height:115%">2. How should
ODB Data be imported?<o:p></o:p></span></b></p>
<p class="MsoNormal"
style="margin-bottom:10.0pt;line-height:115%">I will copy the
following paragraphs in the “Canada Building Import” wiki page
[3] for a detailed discussion…<o:p></o:p></p>
<p class="MsoNormal"
style="margin-bottom:10.0pt;line-height:115%">Since the data
(ODB, OSM and imagery) differ from one municipality to
another, there can be no imports at the national or provincial
level. We have to work on a municipal basis and make sure to
identify all the problems and the corrective measures to apply
when dealing with issues like those I identified [1].
<o:p></o:p></p>
<p class="MsoNormal" style="line-height:115%"><b>2.1 Importing
Locally<o:p></o:p></b></p>
<p class="MsoNormal"
style="margin-bottom:10.0pt;line-height:115%">According to the
import guidelines (step 2), we must not import the data
without local buy-in. However, and contrarily to some European
country, there is usually no such thing as a local OSM
community in each municipality. However, we may find a few
local mappers from time to time. Working on a municipal basis
should allow identifying these local mappers before doing the
import. I often use this tool [2] to identify and contact
local mappers. Once identified, I suggest that…<o:p></o:p></p>
<p class="MsoNormal">- We contact them to explain our intents by
referring to appropriate wiki pages.<o:p></o:p></p>
<p class="MsoNormal">- We wait a week or two to let them respond
nothing, that they have concerns, or wish to help.<o:p></o:p></p>
<p class="MsoNormal" style="margin-bottom:6.0pt">- Without
negative answers we could proceed to the import.<o:p></o:p></p>
<p class="MsoNormal"
style="margin-bottom:10.0pt;line-height:115%">I first suggest
that when a contributor wishes to import ODB for a given
municipality, he first identifies himself as responsible for
the import (we need to create an entry for each municipality
somewhere in the wiki). He can then contact local mappers, as
explain above, and go ahead with the import once everything
settled. For those who already made the import, I suggest that
they review their work since many issues were detected with
some of these imports.<o:p></o:p></p>
<p class="MsoNormal"
style="margin-bottom:10.0pt;line-height:115%">Since there are
only a few local OSM communities in Canada, and because Canada
is large, I suggest not limiting the import of a given
municipality to the people of the concerned province or
region.<o:p></o:p></p>
<p class="MsoNormal" style="line-height:115%"><b>2.2
Pre-processing<o:p></o:p></b></p>
<p class="MsoNormal"
style="margin-bottom:10.0pt;line-height:115%">Once local
mappers have agreed, some pre-processing can be done if
required.
<o:p></o:p></p>
<p class="MsoNormal"
style="margin-bottom:10.0pt;line-height:115%">A few months
ago, I developed a tool that could be used to process the data
[4]. Concerns were raised because the application was
developed using proprietary software. So I documented the
whole process and algorithms in order to see courageous coders
converting it in open source software. In the meantime, and as
long as I have access to an FME licence, I could process the
data, when necessary, prior to make it available through the
task manager.<o:p></o:p></p>
<p class="MsoNormal"
style="margin-bottom:10.0pt;line-height:115%">Proposed
pre-processing [4] includes:
<o:p></o:p></p>
<p class="MsoNormal">- Reading of original ODB data,<o:p></o:p></p>
<p class="MsoNormal">- Removal of near collinear nodes
(simplification), <o:p></o:p></p>
<p class="MsoNormal">- Orthogonalization of buildings (for
corners having near right angles),<o:p></o:p></p>
<p class="MsoNormal">- Tagging of building footprints,<o:p></o:p></p>
<p class="MsoNormal"
style="margin-bottom:10.0pt;line-height:115%">- Providing
files in OSM format.<o:p></o:p></p>
<p class="MsoNormal"
style="margin-bottom:10.0pt;line-height:115%"><i>Proposed
tagging:</i> In addition to the tags produced by the
orthogonalization process [4] and the source tag (<a
href="https://wiki.openstreetmap.org/wiki/Key:source"
moz-do-not-send="true"><span
style="color:windowtext;text-decoration:none">source</span></a>=Statistics
Canada - Open Building Database), the name of the Census
Subdivision provided in ODB data [5] is used to add the
addr:city tag to each building.<o:p></o:p></p>
<p class="MsoNormal"
style="margin-bottom:10.0pt;line-height:115%">The
pre-processing requires parameters that are specific to the
data to process. These parameters were estimated on a
municipal basis using actual ODB data. The processing time
increases exponentially according to the number of buildings
so, it may take a couple of days before the data is available
for a given municipality. Currently, the proposed
pre-processing does not convert terrace buildings into
individual houses nor it tags topological errors.<o:p></o:p></p>
<p class="MsoNormal" style="line-height:115%"><b>2.3. Import
Process<o:p></o:p></b></p>
<p class="MsoNormal"
style="margin-bottom:10.0pt;line-height:115%">After the local
mappers, if any, agreed to the import, the pre-processing
completed when required, we can proceed to the import.
<o:p></o:p></p>
<p class="MsoNormal"
style="margin-bottom:10.0pt;line-height:115%">1- Do not bulk
import the data! Always use the task manager
(<a class="moz-txt-link-freetext" href="http://tasks.osmcanada.ca/">http://tasks.osmcanada.ca/</a>). Select and open a task square in
JOSM. If it’s too big (e.g. too much work or request is too
big to load in JOSM), go back to the task manager and split
the task into smaller squares.<o:p></o:p></p>
<p class="MsoNormal"
style="margin-bottom:10.0pt;line-height:115%">2- Load imagery
layer (Bing or ESRI World Imagery) and align the imagery with
ODB data (i.e. create a new image offset) if necessary
because, unless proven otherwise, ODB should be more accurate
(XY) than most available images especially in hilly areas.<o:p></o:p></p>
<p class="MsoNormal"
style="margin-bottom:10.0pt;line-height:115%">3- Align the
existing OSM content to the image (i.e. after the new offset
is applied) if required.<o:p></o:p></p>
<p class="MsoNormal"
style="margin-bottom:10.0pt;line-height:115%">4- Currently
step 2 and following as described in the wiki [2]. I suggest
merging the Conflation section [6] here and reviewing
everything to take into account the current proposal.<o:p></o:p></p>
<p class="MsoNormal"
style="margin-bottom:10.0pt;line-height:115%"><b><span
style="font-size:14.0pt;line-height:115%">References<o:p></o:p></span></b></p>
<p class="MsoNormal"><span style="font-size:9.0pt">[1] </span><a
href="https://wiki.openstreetmap.org/wiki/The_Open_Database_of_Buildings"
moz-do-not-send="true"><span style="font-size:9.0pt">https://wiki.openstreetmap.org/wiki/The_Open_Database_of_Buildings</span></a><u><span
style="font-size:9.0pt;color:blue"><o:p></o:p></span></u></p>
<p class="MsoNormal"><span style="font-size:9.0pt">[2] </span><a
href="https://wiki.openstreetmap.org/wiki/Canada_Building_Import#Import_process"
moz-do-not-send="true"><span style="font-size:9.0pt">https://wiki.openstreetmap.org/wiki/Canada_Building_Import#Import_process</span></a><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:9.0pt">[3] </span><a
href="http://resultmaps.neis-one.org" moz-do-not-send="true"><span
style="font-size:9.0pt">http://resultmaps.neis-one.org</span></a><span
style="font-size:9.0pt"> (“Overview of OpenStreetMap
Contributors aka who’s around me?”)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:9.0pt">[4] </span><a
href="https://github.com/jfd553/OrthogonalizingBuildingFootprint"
moz-do-not-send="true"><span style="font-size:9.0pt">https://github.com/jfd553/OrthogonalizingBuildingFootprint</span></a><u><span
style="color:blue"><o:p></o:p></span></u></p>
<p class="MsoNormal"><span style="font-size:9.0pt">[5] </span><span
style="font-size:10.0pt"><a
href="https://www150.statcan.gc.ca/n1/pub/92-195-x/2011001/geo/csd-sdr/csd-sdr-eng.htm"
moz-do-not-send="true"><span style="font-size:9.0pt">https://www150.statcan.gc.ca/n1/pub/92-195-x/2011001/geo/csd-sdr/csd-sdr-eng.htm</span></a><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:9.0pt">[6] </span><span
style="font-size:9.0pt"><a
href="https://wiki.openstreetmap.org/wiki/Canada_Building_Import#Conflation"
moz-do-not-send="true">https://wiki.openstreetmap.org/wiki/Canada_Building_Import#Conflation</a><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:9.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:9.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"
style="margin-bottom:10.0pt;line-height:115%"><o:p> </o:p></p>
<p class="MsoNormal"
style="margin-bottom:10.0pt;line-height:115%">Let’s move
ahead!<o:p></o:p></p>
<p class="MsoNormal"
style="margin-bottom:10.0pt;line-height:115%">Daniel<o:p></o:p></p>
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<pre class="moz-quote-pre" wrap="">_______________________________________________
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</pre>
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