I was watching the quiz show "Holding out for a Hero" last night on TV and one of the questions was how many cities are in the UK. The correct answer out of 26, 46 and 66 was 66. Sorry for the spoiler if anyone had recorded it to watch later and couldn't have guessed.
However I idly wondered at the time how accurately UK cities are mapped. This morning, with the help of a Geofabrik British Isles extract and a .poly file I created moments before finding the existing UK one on the Cloudmade website, I can confirm that we have 69. After finding an official list on a UK Gov website[1] and comparing: We are missing: Chichester, Lichfield, Ripon, Salford, St David's, Stoke-on-Trent, and Westminster We have extra: Bournemouth, Chelmsford, Colchester, Ipswich, Jedburgh, Middlesborough, Milton Keynes, Northampton, Reading, and Swindon I have a feeling that some of the extra ones have been tagged as cities for the renderer as rendering of cities doesn't take into account area (of a node?) or population as far as I know. Having said that, the Key:place wiki page[2] seems to suggest that the convention varies by countries with suggested tagging based on population for those countries that haven't established a convention. In other word it fudges the issue because mappers disagree. Map Features[3] suggests "Urban settlement of national importance as defined by national/state/provincial government. May be state capital, provincial capital or center of a metropolitan statistical area. Often over 100,000 people", which leans towards using official city definitions in countries where those exist. So currently, if someone wants a list of UK cities from OSM, they can't get it by using osmosis to extract place=city nodes. Or they can, but they would find our data to be wrong. So, should we correct the tagging of cities in the UK so people can extract correct information? Discuss... Ed [1] http://is.gd/1dUxfR [2] http://wiki.openstreetmap.org/wiki/Key:place [3] http://wiki.openstreetmap.org/wiki/Map_Features#Places _______________________________________________ Talk-GB mailing list [email protected] http://lists.openstreetmap.org/listinfo/talk-gb
