John,
yes, the buildings in Africa are really messed up. But yet, they are there in 
contrast to some largest digital map-makers. Just take a look on some examples 
like here https://goo.gl/CYVahc or here https://goo.gl/UWuBcf or here 
https://goo.gl/9iNYCm or here https://goo.gl/jUuqmS. There are several 10s of 
thousands similar errors like in the examples. But even though the absolute 
number is large, it is only a percent or two compared to the total number of 
buildings in Africa. And as I told you it is possible to repair almost all the 
above illustrated anomalies. It is challenging and I am working on it using the 
source data (XML dump) from some weeks ago.
So, if you are patient for several days, you will get the buildings for Africa 
probably with the best preparation and based on the potential in the source 
data. The data will be in shp format accompanied by some statistics, additional 
geometries for control and a short documentation.
Of course, if you don need these I will not bother you. But at least, you could 
use the stuff as an option to compare if you use other models. Anyway, the 
subject might not be of interest for other members so if you still want the 
buildings we could just switch to bilateral communication about some details 
(for instance Africa, the continent and Madagascar, eventually some small 
islands, in which projection(s) and so on).
Regards, Sandor.

Sent from Mail for Windows 10

From: john whelan
Sent: 28 November 2017 22:13
To: Frédéric Rodrigo
Cc: OpenStreetMap talk mailing list
Subject: Re: [OSM-talk] finding overlapping buildings

The problem is how do you fix them?  Having something directly in JOSM is 
useful. They tend to appear in clusters so step one is find the cluster.  Step 
two is sort the duplicates out.

There really is some very poor mapping of buildings and this at least 
identifies the ones that there should be no disagreement about whether they 
should be deleted or not.

One day we'll sort out what to do about the very badly mapped buildings that at 
least two other mappers have referred to as junk but that's another story.

Cheerio John


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