On Fri, 29 Jan 2016 19:38:46 +0100 Roland Olbricht <roland.olbri...@gmx.de> wrote:
> >> This diversity of tagging is often quoted as a problem for data > >> consumers. Oddly, this is often by people who don't actually use > >> the data but feel it must be awkward. Actually it's not. All OSM > >> data has to processed before use. This processing can be fairly > >> straightforward or really complex, but that's not much to do with > >> tagging diversity. Whatever the processing is (LUA code, SQL code > >> or any other coding) it only has to written once and can be used > >> over and over again. > > > > "but that's not much to do with tagging diversity" - I would > > dispute it, from my personal experience. Tagging diversity IS one > > of real problems in using OSM data. > > Could you please give an example? My first ever attempt to display cycleways went as follows: - display ways tagged as highway=cycleway Why nearly everything is missing? OK, there is also bicycle=designated - display also bicycle=designated Failed due to people adding vehicle=designated, bicycle=designated, horse=designated etc to a normal roads (rare, but enough to result in noticeable errors) - replace bicycle=designated by [highway=path; bicycle=designated] Later I also discovered that [highway=footway; bicycle=designated] combination also appears (due to https://github.com/openstreetmap/iD/issues/2327 ). That would be OK. But it is not going to work properly. There are still cycleway=track ways. Also, [highway=bridleway + bicycle=designated]. Some people decided that inventing bicycle=official makes sense - and to handle it at least [highway=path; bicycle=official] and [highway=footway; bicycle=official] and [highway=bridleway; bicycle=official] would be necessary. There are more accepted in at least some region methods to map cycleways and even more rare methods. For example tagging joined footway + cycleway as [highway=footway; cycleway=lane]. There are many places where my map style would fail, as it would be unable to interpret local tagging scheme. Remapping/retagging my city was very significant part of this map project. In the end about 1/2 of work was adding new data, 1/4 editing data to fit common tagging schemes and creating transformations to handle tagging complexity and 1/4 was making map style. For reference - this project is a horrible mix of Maperitive and Ruby scripts and at least currently resides at https://github.com/matkoniecz/bicycle_map_of_Krakow ). I am not claiming that there are quick & easy ways to reduce complexity - but complexity has some real negative consequences. > If you ask people to misrepresent the reality to fit a fixed tagging > scheme That is clearly not OK, nobody advocates misrepresenting reality. _______________________________________________ talk mailing list talk@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk
