OSM wiki: https://wiki.openstreetmap.org/wiki/Key:building:part It's not in the import wiki though since whoever wrote it didn't know about it at the time. Here's what I mean by mapping 3D features in our case. Say there is a residential tower on a podium. In the StatsCan data usually you would find both of these outlines - large podium outline and smaller tower outline inside it. They would both be tagged with "building=yes" tag. Obviously we can't upload that as-is. We can either just remove tower outline leaving only 2D podium outline. Or, we can tag the tower outline with "building:part=yes". Someone local can add other tags to it later on, such as "building:levels", "building:material", "building:min_level", "addr:housenumber" (if there are two towers on one podium with different house numbers for example), etc. I find the latter approach to be the right one.
On Thu, Jan 24, 2019 at 11:15 AM Nate Wessel <[email protected]> wrote: > Hi Yaro, > > I just had a chance to look at the documentation on the source data and I > wasn't able to find anything about 3D features or parts of buildings being > mapped separately. Are you guessing here, or is there documentation on > this? If so can you point us to it? > > In any case, the big shapefiles from StatsCan don't provide enough > information to reconstruct any 3D geometries, so I'd be inclined to remove > these from the import unless they can be brought in from another source > with better documentation / attribute tagging. (i.e. City of Toronto?) > > Thanks, > Nate Wessel > Jack of all trades, Master of Geography, PhD candidate in Urban Planning > NateWessel.com <http://natewessel.com> > > On 1/18/19 2:48 PM, Yaro Shkvorets wrote: > > Jarek, > There is no question we want this data. I went through much of it in > Toronto and Kingston and I found it to be very good, consistent and > precise. Time-wise it's somewhat current with 2016 ESRI imagery (sometimes > ahead, sometimes slightly behind) and is well-aligned with it. It offers 3D > features (when several buildings appear overlapped in the dataset) but you > just need to be familiar with `building:part` tag to sort through it. I > haven't looked at other provinces but in Ontario I really have no > complaints about dataset quality whatsoever. Also I don't get Nate's > "wildly unsimplified geometries" comment. IMO geometries are just perfectly > detailed. > > > On Fri, Jan 18, 2019 at 2:00 PM Jarek Piórkowski <[email protected]> > wrote: > >> Some more thoughts from me. >> >> Building outlines, particularly for single-family subdivisions as seen >> in Canadian suburbs, are extremely labour-intensive to map manually. >> >> My parents' house is now on OSM - accurately. They live in a city with >> about 10,000 buildings, and about 0.5 active mappers. This wouldn't >> been completed manually in the next 5 years. >> >> An option to do this automatically with a computer algorithm detecting >> objects from imagery could be suggested, but this has not been very >> accurate in OSM in the past, even when there is decent imagery. The >> only other feasible data source is government, where they have such >> data more or less. >> >> The alternative is of course the opinion that we should not have >> building outlines until someone goes through and adds the buildings >> manually. In practice what I've seen done in Toronto is that bigger >> buildings are mapped on best-effort basis from survey and imagery, >> while areas of single-family houses are left blank. This isn't >> _wrong_, and maybe some prefer this. >> >> I would also like to note that building outlines will _never_ be >> completely verifiably up to date. I can't go into most people's >> backyards and verify that there isn't a new addition on their house. A >> building might be legally split into two different properties without >> it being evident from the street. Imagery is out of date the day after >> it's taken, and proper offset can be difficult to establish in big >> cities where GPS signal is erratic. Pragmatically, I can tell you from >> personal experience that building data in lovingly-mapped Berlin is >> also worse than 1 meter accuracy. So again: best effort. >> >> What do we get from having buildings? A sense of land use (arguably >> replaceable with larger landuse areas). A way to roughly estimate >> population density. A way to gauge built-up density. A data source for >> locating buildings in possible flood zones, or fire risk. Statistics: >> as open data, queryable by APIs that are already used, in format >> more-or-less common worldwide. >> >> Examples were given of rowhouse- or de-facto rowhouse-buildings where >> a part is attached to the wrong building. This does not alter any of >> the above examples. It's wrong, but is it substantially more wrong >> than a blank subdivision, or one with only a few buildings mapped? Is >> it better to have a null, or be off by 5%? The legal truth is in >> property records, and we can't measure houses with a ruler, so OSM can >> only be a statistical source. And then there's the question of >> verifiability - some of these buildings are connected to their >> neighbour building inside. I've really struggled at distinguishing >> what exactly is a "building" on Old Toronto avenues even with >> street-side survey. >> >> Bluntly, OSM is not perfect in Canada. I have pet peeves I can quote, >> and I'm sure many of you do as well. If we import, the question is: >> are we making it better? >> >> 1. Do we want this data? >> 2. Is it generally of acceptable quality? >> 3. Is there a mechanism to spot and reject where data is particularly bad? >> >> Cheers, >> Jarek, who should really get back to updating built-last-year stuff at >> Fort York >> >> On Fri, 18 Jan 2019 at 09:31, Kyle Nuttall <[email protected]> >> wrote: >> > >> > The pilot project that took place in Ottawa for all these building >> imports is what got me hooked into OSM in the first place. I would make >> only very minor changes here and there. I even attempted to draw building >> footprints but got burnt out after only doing a single street, which was >> very discouraging for me to continue. >> > >> > When I saw the entire neighbourhood get flooded with new buildings that >> weren't there before, I was entirely intrigued and actually got on board >> with the locals to help with the process. I've been hooked since and have >> been to many meetups afterwards. Helping out with projects completely >> unrelated to the initial building import. >> > >> > I'm entirely of the belief that it is much more encouraging for a new >> user to make a minor change (eg. changing `building=yes` to >> `building=detached`) than it is to add every single minor detail to each >> object from scratch (visiting the location, drawing the building footprints >> manually, adding address data, etc.). It's just overwhelming for a new user. >> > >> > It is very much a cat-and-mouse type scenario with community driven >> projects like OSM. Apparently the issue with this import is the lack of >> community involvement but I can for sure tell you that this import will >> help flourish the community in the local areas. Especially if they only >> need to add or change minor tags than if they would have had to create all >> of this data by hand. With an import this size there is bound to be some >> errors that slip through. That's where the community comes through to >> correct these minor things. >> > >> > This is the whole point of OSM. A user creates an object with as much >> information as they know and the next user comes and adds onto that, and >> the next user adds and/or updates even more. Neither of those users on >> their own could have added as much detail as all of their knowledge >> combined. >> > >> > Are we supposed to just wait for a user who can add every single >> building with centimetre precision and every bit of detail simply because >> we can't? No, of course not. We do the best we can and have other users who >> know more than we do build on that. >> > >> > I fully endorse this import because I would love to see what it does >> for the local communities that apparently need to figure this import out >> for themselves. >> > >> > Cheers, >> > Kyle >> > >> > On Jan. 18, 2019 05:40, James <[email protected]> wrote: >> > >> > As Frederik Ramm once said(sorry i'm paraphrasing from memory please >> don't shoot me) There has never been a GO-Nogo for imports, you bring it up >> on the mailing lists with reasonable delay, is there no objections(in this >> case no one was saying anything about it for 2-3 weeks) then email the list >> that the import would start. >> > >> > On Fri., Jan. 18, 2019, 12:59 a.m. Alan Richards <[email protected] >> wrote: >> > >> > Along the lines of what Jarek said, sometimes silence just means tacit >> acceptance, or that it's not that controversial. There's quite a bit of >> government data here that is supposedly "open" but unavailable for OSM, so >> I'm very glad Stats Can was able to find a way to collect municipal data >> and publish it under one national license. I was surprised myself it hadn't >> got more attention, but I'm firmly onboard with more imports if done with >> care. >> > Manually adding buildings - especially residential neighborhoods, is >> about the most boring task I can think of, yet it does add a lot to the map. >> > >> > I'll admit I hadn't looked at the data quality myself, but I just did >> review several task squares around BC and they look pretty good. Houses >> were all in the right place, accurate, and generally as much or even more >> detailed than I typically see. Issues seemed to be mostly the larger >> commercial buildings being overly large or missing detail, but in general >> these are the buildings most likely to be already mapped. To a large >> degree, it's up the individual importer to do some quality control, review >> against existing object, satellite, etc. If we have specific issues we can >> and should address them, but if the data is largely good then I see no need >> to abort or revert. >> > >> > alarobric >> > >> > On Thu, Jan 17, 2019 at 7:41 PM Jarek Piórkowski <[email protected]> >> wrote: >> > >> > On Thu, 17 Jan 2019 at 21:46, OSM Volunteer stevea >> > <[email protected]> wrote: >> > > Thanks, Jarek. Considering I am a proponent of "perfection must not >> be the enemy of good" (regarding OSM data entry), I think data which are >> "darn good, though not perfect" DO deserve to enter into OSM. Sometimes >> "darn good" might be 85%, 95% "good," as then we'll get it to 99% and then >> 100% over time. But if the focus on "how" isn't sharp enough to get it to >> 85% (or so) during initial entry, go back and start over to get that number >> up. 85% sounds arbitrary, I know, but think of it as "a solid B" which >> might be "passes the class for now" without failing. And it's good we >> develop a "meanwhile strategy" to take it to 99% and then 100% in the >> (near- or at most mid-term) future. This isn't outrageously difficult, >> though it does take patience and coordination. Open communication is a >> prerequisite. >> > >> > Thank you for this commitment. I wish others shared it. Unfortunately >> > the reality I've been seeing in OSM is that edits which are 90+% good >> > (like this import) are challenged, while edits which are 50+% bad >> > (maps.me submissions, wheelmap/rosemary v0.4.4 going to completely >> > wrong locations for _years_) go unchallenged or are laboriously >> > manually fixed afterward. >> > >> > --Jarek >> > >> > _______________________________________________ >> > Talk-ca mailing list >> > [email protected] >> > https://lists.openstreetmap.org/listinfo/talk-ca >> > >> > _______________________________________________ >> > Talk-ca mailing list >> > [email protected] >> > https://lists.openstreetmap.org/listinfo/talk-ca >> > >> > >> > _______________________________________________ >> > Talk-ca mailing list >> > [email protected] >> > https://lists.openstreetmap.org/listinfo/talk-ca >> >> _______________________________________________ >> Talk-ca mailing list >> [email protected] >> https://lists.openstreetmap.org/listinfo/talk-ca >> > > > -- > Best Regards, > Yaro Shkvorets > > _______________________________________________ > Talk-ca mailing > [email protected]https://lists.openstreetmap.org/listinfo/talk-ca > > _______________________________________________ > Talk-ca mailing list > [email protected] > https://lists.openstreetmap.org/listinfo/talk-ca > -- Best Regards, Yaro Shkvorets
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