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
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