Extracting subsets from planet.osm
----------------------------------

In this directory you will find a Perl script that allows you to extract
a subset of the data from within the weekly planet.osm file.  Running the
script is as simple as:

	extract-polygon.pl [-v] -i planet.osm -o gb.osm -p gb.poly

The options used in this example are -i to specify the input file (or you
can use STDIN), -o to specify the ouput file (or you can use STDOUT), and
-p to specify the polygon file.  The polygon file is the only required 
option.

If you run the script with the -h option it will print a full list of the
available options. The -v makes the script verbose and prints out a progress
meter.


Polygon files
-------------

Polygon files are ASCII text files containing a list of longitudes and 
latitudes.  A file can contain more than one polygon so you can extract a
number of different areas with a single command.  An example of a polygon 
defining Great Britain and Ireland (and some of the smaller islands) is:

1
        -0.6450E+01     0.4980E+02
        -0.2000E+01     0.4890E+02
        -0.1850E+01     0.4925E+02
        -0.2080E+01     0.4973E+02
         0.1350E+01     0.5090E+02
         0.2250E+01     0.5258E+02
        -0.0500E+01     0.6130E+02
        -0.8920E+01     0.5785E+02
        -0.1140E+02     0.5130E+02
        -0.6450E+01     0.4980E+02
END

You can also exclude areas by polygon. You do this by prefixing the number
that starts a polygon with a "!". Otherwise it is the same.

Contributed polygon files
-------------------------

In this directory, along with the extract-polygon.pl script and this README
file you will find polygon files contributed by the OSM community.  If you 
want to contribute a polygon either add it to this directory and update the
list below, or email it to Keith Sharp <kms@passback.co.uk>.

Available polygon files:

gb-irl.poly : Great Britain, Ireland, and the Islands.
at.poly     : Austria, <christof@dallermassl.at>
spain.poly  : Spain and Canary and Balearic islands