Hi, David Murn wrote:
OSM, by its nature, is excellent for retaining historic data, for example if a road is realigned, you have a history that shows how it was realigned, or if a road changes name, there exists a history of previous names.
I think that you, just as almost everyone else in this discussion, are wrongly mixing OSM's revision history and true on-the-ground history.
Revision history is there for the sole purpose of storing who has made a certain edit when. The time at which an edit was made has *nothing* to do with the time at which the object started or ceased to exist; the time at which an edit was made is the time when the existing object was first recorded, or when the object's destruction was recorded.
While revision history is nice to create animations about how the OSM data set grows, it is unusable for animations about what happened in the real world.
Properly modelling this would require adding an extra dimension to OSM where each property (tag, location) of an object could receive a validity timespan. Of course this would have to be in *addition* to the normal revision history - I would need to know that, for example, on the 11th of November, 2010, someone changed the validity timespan for the attribute surface=cobblestone on a certain roman road to be 350-200 BC rather than 350-250 BC.
OSM revision history and on-the-ground history are orthogonal. Bye Frederik -- Frederik Ramm ## eMail frede...@remote.org ## N49°00'09" E008°23'33" _______________________________________________ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
