no need for scripts, qgis does this fine via the Vector
menu -> Geometry tools -> Simplify Geometries utility. I
simplified it to 20cm with the , but I think 40cm is too
aggressive.
I already have scripts to compile it into the dataformat
needed to be served.
On Sat., Jan. 26, 2019, 11:16 a.m. Nate Wessel
<[email protected] <mailto:[email protected]> wrote:
Hi all,
The wiki page is indeed looking a whole lot better right
now - my thanks and congrats to everyone who
contributed! There is a still a ways to go, but we seem
to be getting there quickly.
I'll echo John in saying that I would appreciate hearing
from some of the other people who chimed in to express
their doubts about the import. For my part, I'm not
satisfied yet - no surprise, I'm sure ;-). I'm thrilled
that we're talking and working together in the open, and
that addresses the biggest concern I had with the import.
These are the big issues I see remaining:
1. *Validation*: Ideally I'd like to see a good chunk
(more than half) of the data that has been imported
already validated by another user before we proceed with
importing more data. Validation is part of the import
plan, so the import isn't done until validation is done
anyway. My hope is that this will flag any issues that
we can fix before moving forward, and give people time
to chime in on the import plan who maybe haven't
already. I don't want to see everything imported and
only then do we start systematically checking the
quality of our work, if ever. If no one wants to do it
now, no one is going to want to do it later either, and
that doesn't bode well.
2. *Simplification*: James' analysis showed that
simplification could save several hundred megabytes (and
probably more) in Ontario alone. This is totally worth
doing, but we have to document the process and be very
careful not to lose valuable data. I believe there was
also a concern raised about orthogonal buildings being
not quite orthogonal - this is something that we should
handle at the same time, again, very carefully. We
certainly don't want to coerce every building into right
angles. With respect to James, I'm not sure this is
something that can be done with a few clicks in QGIS. I
would be willing to develop a script to handle this, but
it would take me about a week or two to find the time to
do this properly. We would need to simultaneously A)
simplify straight lines B) orthogonalize where possible
and C) preserve topology between connected buildings.
This is not impossible, it just takes time and care to
do correctly.
3. *Speed and Size*: To John's point, it seems like
people certainly are not sticking to the areas they
know, unless they get around a whole hell of a lot more
than I do, and yes this is a problem. The whole Toronto
region was basically imported by two people: DannyMcD
seems to have done the entire west side of the region
(hundreds of square kilometers) while zzptichka imported
the entire east side of the region (again a truly
massive area), both in the matter of a week or two. They
only stopped in the middle where there were more
buildings already and things got a bit more difficult.
The middle is where I live, and when I saw that wave of
buildings coming, I sounded the alarms.
This is way too fast - no one person should be able to
import the GTA in a couple weeks. A big part of the
problem, IMO is that the task squares are much too
large, and allow/require a user to import huge areas at
once. At the least, some of the task squares in central
Toronto are impossibly large, including hundreds or
thousands of buildings already mapped in OSM. Conflation
on these, if done properly would take the better part of
a day, and people are likely to get sloppy.
I would like to see the task squares dramatically
reduced in size as a way of slowing people down, helping
them stick to areas they know well, and keeping them
focused on data quality over quantity. This would also
make the process much more accessible to local mappers
who don't already have tons of experience importing.
4. *Conflation*: I don't think the current conflation
plan is adequate(ly documented). In practice, what
people are actually doing may be fine, but I really want
to see some better thought on how to handle existing
buildings. Right now the wiki says for example "/Before
merging buildings data switch to OSM layer and see if
there are any clusters of buildings without any
meaningful tags you can delete to save time when merging/."
With respect to whoever wrote this, this approach seems
to value time over data integrity and I just don't think
that's how OSM should operate. We need to be more
careful with the existing data, and we need to show that
care with clear and acceptable guidelines for handling
the data that countless people have already spent their
time contributing. We don't do OSM any favours by
carelessly deleting and replacing data. Help convince me
that this isn't what's happening.
Until some effort has been made to address these
concerns, I will continue to oppose this import moving
forward. And to be clear, I don't want to oppose this
import - I have too much else I should be focusing on. I
just don't want to see another shoddy import in Toronto
(or elsewhere).
Best,
Nate Wessel
Jack of all trades, Master of Geography, PhD candidate
in Urban Planning
NateWessel.com <http://natewessel.com>
On 1/26/19 8:49 AM, john whelan wrote:
I'm not certain how this addresses the concerns raised
by Andrew Lester and
Pierre Béland,
and I seem to recall one other person who expressed
concerns.
I think it is important that their concerns are addressed.
Perhaps they would be kind enough to comment on whether
or not this approach addresses their concerns.
Do we have a concern that some mappers have been
importing buildings further than say twenty
kilometers from where they live?
Have you found volunteers of local mappers in
Alberta
British Columbia
Manitoba
New Brunswick
Newfoundland and Labrador
Northwest Territories
Nova Scotia
Nunavut
Ontario
Prince Edward Island
Quebec
Saskatchewan
Yukon
Who will be willing to oversee the import in each province?
Does this mean the smaller provinces may not see any data?
How will you handle cities of say 80,000 population in
a smaller province who have an interest in seeing their
buildings available but have no idea on how to contact
the provincial group?
If we go back to earlier times it was a suggestion in
talk-ca that we use the single import approach and it
was mentioned at the time there didn't seem to be a
list of local mapper groups in Canada.
I'm not saying the approach of a single import as far
as the import list and talk-ca followed by a procedure
of locally organised mappers bringing in the data is
wrong I'm just trying to ensure the project moves
forward and we are in agreement.
Thanks
Cheerio John
On Sat, 26 Jan 2019 at 00:17, OSM Volunteer stevea
<[email protected]
<mailto:[email protected]>> wrote:
Thanks to some good old-fashioned OSM
collaboration, both the
https://wiki.osm.org/wiki/Canada_Building_Import
and
https://wiki.osm.org/wiki/WikiProject_Canada/Building_Canada_2020#NEWS.2C_January_2019
have been updated. (The latter points to the former).
In short, it says there are now step-by-steps to
begin an import for a particular province, and that
as the steps get fine-tuned (they look good, but
might get minor improvements), building a community
of at least one or two mappers in each of the
provinces with data available, the Tasking Manager
can and will lift the "On Hold" or "Stopped" status.
Nice going, Canada!
See you later,
SteveA
California
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