[Talk-ca] Building Import update
Nate Wessel
bike756 at gmail.com
Sat Jan 26 16:42:46 UTC 2019
Does that preserve topology between buildings that share nodes?
Nate Wessel
Jack of all trades, Master of Geography, PhD candidate in Urban Planning
NateWessel.com <http://natewessel.com>
On 1/26/19 11:31 AM, James wrote:
> 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 <bike756 at gmail.com
> <mailto:bike756 at gmail.com> 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
>> <steveaOSM at softworkers.com <mailto:steveaOSM at softworkers.com>> 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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