Hi, 2009/10/8 Lynn W. Deffenbaugh (Mr) <[email protected]>: > I'm developing a client that uses OpenStreetMap tiles and overlays > coordinate (lat/lon) information above it. It's custom C coded, so I > can't use any of the libraries out there. > > I understand the discussion on the following URL about the tile names > and the long2tilex, lat2tiley, tilex2long, and tiley2lat functions. > > http://wiki.openstreetmap.org/index.php/Slippy_map_tilenames > > However, at zoom levels less than 4 (or so), I get a worsening offset to > the north and south of the equator as I map objects onto the maps.
This is a wild guess because I don't have the code but the effect is as if you were calculating the visible map's corner's coordinates (for example using the Bounding Box around Tiles fromulas from the wiki page) and then interpolating lat and lon to place the markers. Instead you need to project the coordinates of each marker to 900913 (i.e. lat2y) and then display. Cheers _______________________________________________ dev mailing list [email protected] http://lists.openstreetmap.org/listinfo/dev
