On Fri, Jan 18, 2008 at 01:14:03PM -0800, James McManus wrote: > Is resolution (map units per pixel) in OpenLayers that same as a map scale?
No. Scale is a false claim of 'screen units per on-the-ground units": 1:19000 (supposedly) means 1 inch on screen = 19000 inches on the ground. This isn't true, of course: there is an implicit assumption that the server knows how many pixels there are in an inch on the screen, which it can't, since screens change resolution. A 256 pixel wide image on the screen at 800x600 is way larger than at 1600x1200. So, it's based on the guess of 72DPI (in MapServer -- in GeoServer it matches the SLD standard at 90.something DPI). To get resolution from scale, use OpenLayers.Util.getResolutionFromScale(19000, map_units), where map_units is one of 'inches', 'mi', 'm', 'km', 'dd', 'yd', 'nmi', 'ft'. Regards, -- Christopher Schmidt MetaCarta _______________________________________________ Users mailing list [email protected] http://openlayers.org/mailman/listinfo/users
