[OSM-talk] Why the HOT obsession with low quality buildings in Africa ?

Robert Banick rbanick at gmail.com
Mon Jul 2 11:26:07 UTC 2018


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 <61sundowner at 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.
>
>
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