Projection

Raw OSM data (found in planet.osm and extracts) is in WGS-84.

Most slippy maps, including OSM's main slippy map layer, are projected in Web Mercator projection.

For clarification on projections, see: <http://trac.osgeo.org/proj/wiki/FAQ> <http://alastaira.wordpress.com/2011/01/23/the-google-maps-bing-maps-spherical-mercator-projection/> For information on the projection and converting between lon/lat and tile formats, see Slippy map tilenames.

Software

• PROJ — command-line tools and library

See also

• Wikipedia:Map projection
• Mercator
• Converting to WGS84