This is an excellent idea. I didn't even notice this. THe bandwidth and storage perks of doing this across large areas could be tremendous. I hope this can be done, I would not have even suggested this in fear of it going nowhere.
Think I am going to start looking for similiar problems in my vicinity. Regards Marlon On Sun, Feb 10, 2013 at 11:05 AM, David Schneider < [email protected]> wrote: > Hi List! > > I searched an address in the eastern parts of Cape Town, and I was > suprised that nomatim didn't report it as residential. I checked the > data, and found that vast parts of Cape Town's residential areas are > made up from unclassified roads instead of residential! > From the metadata, this seems to be the result of an import some > years ago. > > I feel this should be fixed. I don't know if this can be done auto- > matically, or a manual community effort is required. My proposal would > be to select "user=Firefishy maxspeed=60 highway=unclassified" in JOSM > and change all to residential. Now, a few roads that should be > unclassified will be residential, but the ratio seems to be 99% wrong > now vs. 1% wrong after this change. Of course, roads that have been > touched since the import will missed by this, but there will be an > improvement for sure. > > Another thing that I noticed is that the roads are massively over-noded. > http://www.openstreetmap.org/browse/way/32216567 demonstrates both. It > should be residential, and if you compare to aerial images, the straight > section is represented with 6 nodes, 3 of them within 5m. I presume this > comes from calculating the centerline of a full shape, as the road widens > towards the east, where the many nodes are. > (I would map that road with 3 nodes, with the two on the eastern sides > interfacing between the NW-SE road, going away at 90° from there. I.e. > making a slight right turn when going east. The data is just the opposite, > going to the left, which gives an odd angle that is not there in reality > when you come from the south and turn east.) > > I downloaded a section of Cape Town, exported to GPX and used gpsbabel > to apply the Douglas-Pecker algorithm with 1m max deviation. The number > of nodes went down to less than half! So maybe removing some excess nodes > could be performed during any update. > > Best, > David > > > > _______________________________________________ > Talk-ZA mailing list > [email protected] > http://lists.openstreetmap.org/listinfo/talk-za > >
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