It's data like here in Markar we're talking about still right? http://osm.org/go/wq63Lv3C
I don't think we should *bulk* delete any data in Somalia, but if I was working on the map in this area I would have no hesitation in deleting data like this and re-adding road layouts back in from bing. The imported data might possibly be geolocated (by GPS) more accurately than bing imagery... possibly... but it's clearly *very* inaccurate in terms of basic topological road layout. I think we need to be bold about fixing it up. Harry ----- Original Message ----- From: Iván Sánchez Ortega <[email protected]> To: [email protected] Cc: Sent: Monday, 5 November 2012, 15:19 Subject: Re: [HOT] Somalia import from 2011 On Domingo, 4 de noviembre de 2012 16:58:51 Kate Chapman escribió: > I looked at the links you sent, I'm not sure why we would delete the > data though. Yes it is imperfect, but I believe it was collected by > GPS. The imagery at least suggests there are roads in those areas > where you are pointing. > > Schuyler who did the data conversion for the import might have some > more insight. Oh, I remember this. I think I've done about 30% of all the Somalia import, so I'll jump in: > Lot of streets, but 98% i delete because it is not fitting. > Only primary road are fitting. 98%??! Oh, c'mon. The imported data wasn't *that* bad. Yes, it has kinks; yes, it has tracks tagged as roads; yes, it has lots of that awful "highway=road" tag combination. That doesn't mean that you should delete all that. If the problem is positional accuracy, then: * Provide a data source with better accuracy. Now, you might think that Bing imagery is perfect and all that. Well, don't. Fitting aerial imagery to the ground truth is a non-trivial thing, and by my experience (and other OSMers' experiences), you cannot expect this from Bing. * Provide GPS traces if you can. Lots. GPS traces in any given area will give you an idea of the *local* deformation, if any, of the aerial images. Emphasis on the "local". If a road is offset 10 meters, you cannot expect that offset to be the very same 20 kilometers away. * Fit the data to that accurate data source. Don't delete data unless you're certain that the features aren't on the ground. Please. -- Iván Sánchez Ortega <[email protected]> <[email protected]> Homer no function beer well without. -- Homer Simpson _______________________________________________ HOT mailing list [email protected] http://lists.openstreetmap.org/listinfo/hot _______________________________________________ HOT mailing list [email protected] http://lists.openstreetmap.org/listinfo/hot
