Low quality building mapping is pretty general in Africa, I mentioned Malawi still has some 4,805 duplicate buildings in the HOT mailing list very recently which as a percentage of the buildings mapped is probably fairly low but is still a concern. The problem is one of data quality, is OSM reliable? and if I want to promote a commercial alternative the data quality of buildings in Africa is a weak point of OSM. Can you trust the buildings mapped in OSM?
The mappers seem to be mappers for a day or possibly three and having spoken to one or two training is seen as a waste of time they just want to map. I get the impression that mapping buildings is seen as a way of engaging people and bringing something to their attention as much as mapping accurate buildings. Perhaps a better way would be to map the village outline and tag them with the number of buildings on a date? Cheerio John On 2 July 2018 at 07:26, Robert Banick <rban...@gmail.com> wrote: > Many humanitarian groups use buildings as a rough proxy for population > (density), or to ensure every household is covered during a vaccination > campaign, or simply to navigate. Likely they use them for a combination of > the three. As Phil says, it’s best to read the specific task. > > As a side note, it’s helpful to be more specific than the entire continent > of Africa, which is a very, very large and diverse place. If you can note > individual problematic countries, as Frederic does, it helps us to identify > sources of error or verify there was a legitimate humanitarian or > community-building reason behind any fall in quality. > > On Mon, Jul 2, 2018 at 4:16 PM Warin <61sundow...@gmail.com> wrote: > >> On 02/07/18 18:52, Frederik Ramm wrote: >> >> > Hi, >> > >> > On 02.07.2018 10:24, Jean-Marc Liotier wrote: >> >> churning out buildings like demented stonemasons trying to reach their >> weekly quota >> >> of gamified task-managing ! >> > I recently stumbled upon >> > >> > https://www.openstreetmap.org/#map=15/-6.8958/39.1623 >> > >> > (Tanzania) and had a similar thought. The buildings there are at least >> > square and largely match aerial imagery, but this, too, looked like >> > supercharged one-trick-pony image tracing combined with very little on >> > the ground knowledge (e.g. quite a few roads and tracks clearly visible >> > on the imagery are not traced, and from someone local you'd expect the >> > occasional POI or label). >> > >> > Someone must have buildings very high on their priority list (don't even >> > know if HOT are involved but it certainly doesn't look like local >> mapping). >> > >> > It will be interesting to learn why buildings are so important. Or are >> > they just the lowest-hanging image tracing fruit, or just easier to >> count? >> > >> I have been mapping a few buildings lately - mainly to add addresses to. >> Past mappers have placed a few POI ... but they tend not to be too >> precise - e.g. between buildings or on the footpath. >> Once the building outline is there then you see the discrepancy. And any >> further additions of POI can be guided by the building outlines. >> >> I hope 'my' buildings are a little better that what is described above, >> some of that depends on the imagery, >> some in the pride of workmanship and some on the fatigue of the mapper. >> Certainly any HOT manager who rewards the number of things done should be >> alert to the quality reduction that such motivation brings. >> >> One of the good things about adding addresses .. you notice things like >> the road name is wrong. >> >> >> _______________________________________________ >> talk mailing list >> talk@openstreetmap.org >> https://lists.openstreetmap.org/listinfo/talk >> > > _______________________________________________ > talk mailing list > talk@openstreetmap.org > https://lists.openstreetmap.org/listinfo/talk > >
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