2011/8/29 Martin Koppenhoefer <[email protected]> > We have been recently discussing on the German ML about > landuse=residential. In Germany many mappers were mapping subdivisions > / neighbourhoods [1] with landuse=residential. This led to very rough > landuse information, because in order to keep the (sometimes quite > big) area as a whole they are forced to ignore landuses that don't > fit. > > I think that the information about these areas belongs to a distinct > entity and would best fit into the "place"-namespace because I see > them as subdivision of settlements (or more precise subdivisions of > what we call "suburb" in OSM). > > If we could agree that the information about which areas as a whole > form a distinct unit (part of a suburb) should go into the place tag, > we would be more flexible when deciding where to apply landuse to. > Part of the current discussion results from the mixing of namespaces: > landuse is used to map settlement subdivisions which are IMHO defined > by other properties (like morphology, history, culture, typology, ...) > then just similar landuse. There is also areas which do combine > different subareas with different landuses (impossible to map this > with landuse-areas without either ignoring bigger parts of different > use or loosing the entity as a whole). > > There are several questions in this context which are generally still > open in OSM: > > 1. does the road belong to the landuse at its sides? > -- as we don't (yet?) tag highway-areas for streets that are > represented with a centre line this is an ongoing debate. For railways > this is easier to decide because there will be landuse=railway along > the tracks. Some mappers advocate to reuse street nodes others prefer > to map these areas at the actual border of the parcels (or the > estimation of the latter). Some pros and cons can be found here: > http://wiki.openstreetmap.org/wiki/Talk:Key:landuse#How_to_map > > 2. What is the desired granularity for landuse? > -- Shall landuse-areas be huge areas comprising several streets and > blocks, or is it desirable to indicate the use of each lot if it is > differing from the surrounding? Or could the landuse areas even go > below single plot size? > > > My personal answer on these questions is currently: > To me a public road is a different landuse. Although it will not harm > if we initially approximate the landuse with bigger areas comprising > inner roads the ideal would be to have equal landuse in block-size > units. This is most easily refinable and would also give the > information of outer plot limits (adjacent to the road) so that you > could infer the public land of the road. > > I would not go below the size of single plots (if there is not very > good reason and a very big plot) and I would also still adhere to the > rule of "predominant" use: if there is a building with offices in the > ground floor and 3 storeys of apartments above this would be > landuse=residential to me. If there was a whole plot with a factory > inside a residential area I would tag this plot as landuse=industrial. > Summed up the desired granularity I suggest to agree on is plot size > for landuse (but we will not necessarily map all plots as distinct > areas, it can also be bigger polygons). > > Cheers, > Martin > > http://wiki.openstreetmap.org/wiki/Tag:landuse%3Dresidential > http://wiki.openstreetmap.org/wiki/Land_use_and_areas_of_natural_land > > [1] Due to political, cultural and economic differences I am not sure > if it makes sense to use the terms subdivisions / neighbourhoods > because I guess the precise meaning is somehow different. >
As you already know, I totally second all of your points. I've used block-size landuse polygons (or smaller, if a significant portion deserved distinction) in urban areas and lot-size onefor agricultural fields. I've been tagging like this for about a year, and the map is coming out pretty nice. Regards, Simone
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