2014-03-13 20:54 GMT+00:00 Ilpo Järvinen <[email protected]>: > On Thu, 13 Mar 2014, Christian Quest wrote: > >> Regarding import related tags, some are really useless, some like unique IDs >> have not been sucessfully used in many cases up to now, but this doesn't >> mean we will never be able to take advantage of them. > > I've never really understood why one would _ever_ want to have the foreign > IDs, unique or not, for things that should remain spatially stable > (roads, buildings, etc.) because the foreign dataset should be rather > trivially diffable against older version of itself. That way, the IDs of > the foreign data are pretty useless to begin with because the diffing > produces the very cases that would need to be checked regardless of IDs. > Obviously the previous version(s) need to be preserved though for the > diffing to be possible. > > Besides, the foreign unique IDs usually don't have well defined rules > anyway, so in case they redo something there would be rather little > guarantees on how the foreign IDs will be in the end. Which is pretty > similar results as what we get ourselves with OSM ids when we edit > by splitting and joining. > > For POI type data where re-location is much more realistic compared with > rather fixed features such as roads and buildings, I can somewhat > understand that there might be some use for the foreign IDs but even there > the update process would probably get most out of the foreign data by > diffing foreign dataset against itself first.
I'd just like to point out that there exists a world of data outside OSM, and foreign IDs are very useful in combining OSM data with other datasets to derive new insights, new services, etc. http://linkeddata.org/ Dan _______________________________________________ Imports mailing list [email protected] https://lists.openstreetmap.org/listinfo/imports
