The issue is the quality of the mapping, nothing else. I attended one of these geoweek events and we used JOSM with the building_tool plugin. The mapping of buildings was accurate even though 75% of the mappers had never used JOSM before. There was no formal validation done but I verified each mappers work as they did it. I got the impression that the mappers enjoyed the exercise and I think for me that was the most important thing. Mapping should be fun.
There was no mention of the work would be validated nor did we record the mappers userids to ensure which mappers had mapped. Other mappers had marked tiles done on the grid. I was under the impression that Stats Canada was involved but was later assured by them that this was not the case. The problem of lots of new mappers producing low quality work really reared its head during the Nepal crisis. I do mainly validation on HOT projects in Africa and I ended up pulling in chunks of Africa and just trying to clean up the map. Currently I'm looking at one mapper who has added more than a thousand ways with one tag I think it says source=PGS. Data quality is a major issue in OpenStreetMap. Recently someone gave up when looking for area=yes or buildings drawn in iD but left untagged for the most part. I think in Europe it was 100,000 or more worldwide it was far higher and that's when the person looking at it gave up. There are many examples in Africa of groups of buildings being mapped as one building and labelled building=house. That's what we are trying to avoid. It is possible to correctly map a building in iD I've seen it done but it takes time. It is far easier to sort of roughly get it right and roughly means not accurately. I think the thing we need to avoid is a feeling the mapper needs to get a tile done. That's when they start to rush things. Building validation? I can think of no validator who enjoys having to take two or three times longer to correct someones's work than it would take them to map it in JOSM with the building_tool in the first place. I'm unable to even think of a case where a project has been validated and the buildings corrected. When I validate I'm trying to correct the mapper's work and give them feedback so they will map more accurately in future. There is no point in doing this to someone who will map once. It's a waste of my time. The wiki page you pointed to, I wrote much of it. the most important part which you skipped is feedback from a user. Why do we validate? “OpenStreetMap is often the only source of maps, but the data quality is very uneven. I wish they’d put their more experienced mappers onto validation.” This is a quote from an individual who used OpenStreetMap data (HOT) in the field. Note the comment the data quality is very uneven and that's what we are trying to address. Your particular maperthon may have produced good work, my lot certainly did but many mappers using the tag did not and that is the issue. By the way we do have fewer mappers per square kilometre than Germany does and we have used CANVEC data to get a basic road network in. In Ottawa we've used Open Data to bring in the bus stops. The basic Canadian map isn't bad but if we had as many mappers per square kilometre as Germany does then no doubt it would be better. Our population density is also lower by the way if you hadn't noticed. Cheerio John On 22 November 2017 at 21:28, Tim Elrick <o...@elrick.de> wrote: > Hello all, > > As you know Open Mapping Group McGill (OMG McGill) organized one of the > mapathons last week for the town of Williams Lake, BC. For the turnout > please turn to Julia's website published earlier today on the list. > > As a mentor of the group I might be the 'director' of this event > according to the proposed policy by the OSMF board. In this role, I want > to assure you that we tried to do our best to teach new mappers how to > do their job properly, as Charles stated on this list yesterday. And > judging from a preliminary analysis of the data I conducted with the > overpass api, the participants did a pretty good job. > > Of course, the data needs validation, which we will conduct in the next > couple of days. However, I do not see the rush proposed on this list > earlier. Ideally, validation would happen right after the mapping event > (as set out in this manual for HOT tasks [1]). In the real world, we all > have our jobs, families and other voluntary engagements, that sometimes > do not allow to act accordingly. I further think it is not even > necessary for tasks that are not related to immediate disaster response > or include ways tagged with a highway tag (in the later case it might > confuse navigation apps if not validated right away). In many cases, > validation, or better, correction of data entered by individual mappers > (not part of group events) was (and still is) done many days or even > months after the data was entered, depending on whether an experienced > mapper has an eye on a certain region or not. With regards to buildings > in areas where there existed no respective data before, I do not see any > need for rushing. > > The important thing is that the organiser of a group event makes sure > that the data entered by participants of the event *is* validated to > ensure data quality. And we will. To this end, I appreciate that > long-term members already offered to help us there (thank you, Charles!). > > I still consider mapathons a legitimate way to draw attention to OSM, to > advocate for open data, and to show the potential of OSM data and the > lack thereof in many parts of the world, including Canada. From the > experience of our first mapathon I got the impression that we instigated > a vast interest in open mapping (which, I think, is a valid goal on its > own right) and I expect quite a couple of returning participants to our > next events, in which we will train them further on the complexities to > produce good OSM data. By continuing, we might be able to motivate one > or two persons to turn into long-term mappers; this is, by the way, > totally in line with the long-tail phenomenon researchers found in all > crowd-sourcing projects. > All those reasons I mentionend, are, I think, worth it continuing doing > what we did. I would appreciate, if the attitude towards group mapping > events were less hostile on this list and on OSM as such (I am aware of > less fortunate attempts conducting group mapping events recently; but > try not blame them, but give them a hand to do it better next time - and > I know you did, but some of them apparently did not understand how > communication works in OSM). Try to give them the benefit of the doubt: > most mappers, even in group event, do this voluntarily and because they > want to enjoy extend this great geodatabase! > > IMHO, OSM cannot do without those events, because we do not want to > leave the future of OSM only to businesses and their paid mappers (and > we have seen that in some countries, including Canada, there might not > be enough people who find their way to OSM without those events). > > Tim > > > [1] > http://wiki.openstreetmap.org/wiki/OSM_Tasking_Manager/ > Validating_data#When_do_we_validate.3F > > > _______________________________________________ > Talk-ca mailing list > Talk-ca@openstreetmap.org > https://lists.openstreetmap.org/listinfo/talk-ca >
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