Silly question perhaps - is there any obvious way to map between an OS MasterMap TOID and an OSM building equivilant i.e. removing the need for using licenced content? asked 10 May '11, 10:19  Angusmac |
One Answer:
Simple answer NO The longer answer is much more involved, complex, and intriguing. So I can't do it justice here, just a few salient points. I doubt if anyone has tagged an object in OSM with a TOID, and as OSM contains data sourced from or derived from Ordnance Survey Open Data it's not clear that the conditions of the royalty-free usage policy can be met. It might be possible to keep a separate database relating OSM object ids to TOIDs. The main problem is that the OSM object ids are not persistent. Most people rely on spatial location for relating entities from different systems. There is a small amount about this on the OSM wiki External IDs have been retained for objects in other parts of the world (e.g., TIGER Line, NHD reach codes), but it is not entirely clear whether this policy was useful. In fact for the TIGER data it is pretty clear that it wasn't. In general I think this has been done "so that we can update the data in the future", whereas the main valid usage is to be able to link the OSM geographical data set with other data (e.g., rainfall, water levels, flow rates, train timetables, traffic volumes etc). It's conceivable that someone might develop a system for persistent OSM IDs, perhaps for an easily managed subset such as road data. Given OSM's freeform tagging the hard bit is deciding what primitives should be used. The mechanism to manage the persistent IDs (even though that will probably require some manual intervention) is a lot easier to conceive. answered 10 May '11, 10:50  SK53 ♦ |
