Am 12.09.11 09:56, schrieb Alan Teeder: > Google maps are notoriously incorrect on co-ordinates. Even their own road > map overlay does not align perfectly with the scenery. You can check the > accuracy yourself if you have a GPS receiver and visit a set of easily > identifiable points like road junctions.
Hi Alan I see now also some differences between OSM and "our" apt.dat and the title of this post is probably wrong (as many other details sometimes coming out here from the university of half-knowledge). Some of the airports and runways fit exactly on all the maps. Maybe "edited" airports ? I dont know, it is very difficult to verify for me, maybe I am on some bad and exotic examples only. (I was thinking about what happens with "wrong" runway coords from apt.dat, i.e. when this data is processed via shapes with recent landcover and height data for FlightGear scenery, coming from other resources. But I confess this gives me to much smoke over my head, also without taking slopes and hills into account). > > Point positions of aeronautical navaids and airfields have mostly been well > surveyed and their positions should therefore be accurate. > Yes, I think (or hope) so ;-) Also here, I only see differences between apt.dat and other geodata. We use X-Plane data, OSM uses another aeronautical database with more than 40000 airports recently in public domain (ourairports.com). I dont know if this is based on the older but unfortunately disappeared DAFIF resources too, but anyway it looks like it is also an interesting collection and has a "living" updater community. I just discovered this one, I will do some private examples with this data. And be quiet for the rest of the year, or at least for some days. Cheers, Yves ------------------------------------------------------------------------------ BlackBerry® DevCon Americas, Oct. 18-20, San Francisco, CA Learn about the latest advances in developing for the BlackBerry® mobile platform with sessions, labs & more. See new tools and technologies. Register for BlackBerry® DevCon today! http://p.sf.net/sfu/rim-devcon-copy1 _______________________________________________ Flightgear-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/flightgear-devel
