The residential tag should be used for an area not a house. On Wed, 13 May 2020 at 14:38, Donie Kelly <donie.ke...@gmail.com> wrote:
> Don’t buildings have tags? Did I see a residential tag? Is it used in all > cases? > > > On 13 May 2020, at 13:24, Colm Moore <colmmoor...@hotmail.com> wrote: > > > > Hi, > > > > Inspired by seeing the estimate in the Microgrant application of 5.5 > million buildings on the island of Ireland, I did some number crunching. > > > > I downloaded the populations of Kilkenny townlands (1,500+) from the CSO > and analysed the population against the number of buildings per civil > parish (100+) for County Kilkenny. This is assuming Kilkenny has all or > nearly all buildings mapped. Based on my inspections, this is largely true. > > > > The CSO data is somewhat distorted for the Kilkenny city area (100+ > townlands), due to the way the CSO have arranged the townlands and civil > parishes. I could look at this in more detail, but there would be a few > hours of effort (unless someone has a simple way of calculating number of > buildings per area, for a large number of areas). > > > > I calculated the 'number of buildings per civil parish' using the > Overpass Turbo query [building=* in "civilparishname, Kilkenny"]. Overpass > Turbo gives a summary of the data in the bottom right corner of the screen, > e.g. > > > > Loaded – nodes: 4261, ways: 867, relations: 2 > > Displayed – pois: 0, lines: 0, polygons: 866 > > > > I took the number of polygons to mean the number of buildings (this > might not be perfect - I don't know how those numbers add up). > Additionally, some polygons, e.g. building=terrace represent several > buildings, while in other cases buildings may have been crudely split or > joined-up. > > > > Depending on the civil parish, we're looking at 0.32-2.29 polygons per > capita (0.44-3.15 people per building). Rural areas ten to have more > polygons per capita, especially due to farm outbuildings, while urban areas > have fewer polygons per capita, due to apartments buildings and > semi-detached buildings (e.g. two square houses joined together might have > only six nodes). > > > > I also calculated 4.40-5.83 nodes per polygon. This means some civil > parishes have predominantly rectangular polygons / buildings, whereas > others have many L-shaped or other-shaped polygons / buildings. > > > > As I wasn't able to immediately get some 'number of buildings per civil > parish' numbers (Overpass Turbo had problems returning them, possibly due > to duplicate names and variations in name spellings), I had to calculate > them from their component townlands, using the Overpass Turbo query > [building=* in "townlandname, civilparishname, Kilkenny"]. > > > > Depending on the townland, we're looking at 0.23-8.00 polygons per > capita (0.13-4.37 people per building) and 3.91-6.45 nodes per polygon > (i.e. some townlands have large numbers of semi-detached or terraced > buildings, whereas others have a high number of complicated-shape polygons > / buildings or buildings with too many mapped nodes). It is usual to see > more extreme spreads when looking at smaller areas. > > > > I'm coming up with about 5.4 million (close enough!) buildings for the > whole island, assuming the pattern is the same everywhere. However, as > shown by analysing the smaller areas, there is variation and the 'final' > number will vary from that. Of course, given that OSM is an ongoing > project, there will never be a final number. > > > > Colm > > VictorIE > > _______________________________________________ > > Talk-ie mailing list > > Talk-ie@openstreetmap.org > > https://lists.openstreetmap.org/listinfo/talk-ie > > _______________________________________________ > Talk-ie mailing list > Talk-ie@openstreetmap.org > https://lists.openstreetmap.org/listinfo/talk-ie > _______________________________________________ Talk-ie mailing list Talk-ie@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-ie
