Am 09.01.2010 01:27, schrieb Dave F.: > Martin Koppenhoefer wrote: > >> still you are ignoring projection and earth form, or are you talking >> about a tunnel (you will have to dig into the earth to get a straight >> line or decent length)? >> > I'm aware of the concept that the earth is not flat. > > But... This is a two dimensional map. IFAIK there is no 3d data. The PoV > of viewing the OSM data via the likes of Mapnik is always through the > surface of the earth to the centre of the earth. Therefore a line such > as this Oz highway is, when viewed in a map, going to be straight. > AFAIK this is not correct. First of all the PoV of Mercator projection is not going through the center of the earth. It's a somehow stretched cylindrical projection and it goes through the north-south-axis. The way it is stretched causes that angles on the earth are the same as on the map. I'm not completely sure, but I believe the only straight lines that correlate between earth's surface and Mercator projected maps are the equator and all great circles parallel to the meridians.
Greatings: Martin Siegel _______________________________________________ talk mailing list [email protected] http://lists.openstreetmap.org/listinfo/talk
