[OSM-talk] finding overlapping buildings

[SandorS]

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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