NAME

       Geo::OSM::Tiles - Calculate tile numbers for OpenStreetMap

SYNOPSIS

         use Geo::OSM::Tiles qw( :all );

         $zoom = 13;
         $lat = 49.60055;
         $lon = 11.01296;
         $tilex = lon2tilex($lon, $zoom);
         $tiley = lat2tiley($lat, $zoom);
         $path = tile2path($tilex, $tiley, $zoom);
         $tileurl = "http://tile.openstreetmap.org/$path";

DESCRIPTION

       This module provides functions for calculating the path to a map tile at OpenStreetMap out
       of geographic coordinates.  The path of a tile at OSM has the form
       "$zoom/$tilex/$tiley.png".  The numbering scheme is documented in the OSM wiki, see the
       link below.

   "lon2tilex($lon, $zoom)"
       Returns $tilex for the tile at longitude $lon and zoom level $zoom.  The longitude must be
       in the range "-180.0 <= $lon < 180.0".  The zoom level must be a non-negative integer.

   "lat2tiley($lat, $zoom)"
       Returns $tiley for the tile at latitude $lat and zoom level $zoom.  The latitude must be
       in the range "-85.0511 <= $lat <= 85.0511".  The zoom level must be a non-negative
       integer.

   "tile2path($tilex, $tiley, $zoom)"
       Composes the path to the tile at $tilex, $tiley, and $zoom at the OSM server.  $tilex and
       $tiley must be integers in the range "0..2**$zoom-1".  The supported range of zoom levels
       depends on the tile server.  The maximum zoom for the Osmarender layer is 17, it is 18 for
       the Mapnik layer.

   "checklonrange($lonmin, $lonmax)"
       Checks whether $lonmin and $lonmax are within the allowed range of the longitude argument
       to "lon2tilex".  Returns "($lonmin, $lonmax)" unchanged if they are ok or corrected values
       if not.

   "checklatrange($latmin, $latmax)"
       Checks whether $latmin and $latmax are within the allowed range of the latitude argument
       to "lat2tiley".  Returns "($latmin, $latmax)" unchanged if they are ok or corrected values
       if not.

SEE ALSO

       <http://wiki.openstreetmap.org/wiki/Slippy_map_tilenames>

AUTHOR

       Rolf Krahl <rotkraut@cpan.org>

COPYRIGHT AND LICENCE

       Copyright (C) 2008-2010 by Rolf Krahl

       This library is free software; you can redistribute it and/or modify it under the same
       terms as Perl itself, either Perl version 5.8.8 or, at your option, any later version of
       Perl 5 you may have available.