NAME

Geo::Heatmap - generate a density map (aka heatmap) overlay layer for Google Maps

VERSION

version 0.08

REQUIRES

Moose Storable CHI Image::Magick

METHODS

tile

 tile();

  return the tile image in png format

ATTRIBUTES

debug cache logfile return_points zoom_scale palette

USAGE

Create a Heatmap layer for GoogleMaps

    my $ghm = Geo::Heatmap->new();
    $ghm->palette('palette.store');
    $ghm->zoom_scale( {
      1 => 298983,
      2 => 177127,
      3 => 104949,
      4 => 90185,
      5 => 70338,
      6 => 37742,
      7 => 28157,
      8 => 12541,
      9 => 3662,
      10 => 1275,
      11 => 417,
      12 => 130,
      13 => 41,
      14 => 18,
      15 => 10,
      16 => 6,
      17 => 2,
      18 => 0,
    } );

    $ghm->cache($cache);
    $ghm->return_points( \&get_points );
    my $image = $ghm->tile($tile);

You need a color palette (one is included) to encode values to colors, in Storable Format as an arrayref of arrayrefs eg

    [50] = [34, 45, 56]

which means that a normalized value of 50 would lead to an RGB color of 34% red , 45% blue, 56% green.

zoom_scale

The maximum number of points for a given google zoom scale. You would be able to extract to values from the denisity log or derive them from your data in some cunning way

cache

You need some caching for the tiles otherwise the map would be quite slow. Use a CHI object with the cache you like

return_points

A function reference which expects a single hashref as a parameter which defines two LAT/LONG points to get all data points within this box:

      $r->{LATN}, $r->{LNGW}), $r->{LATS}, $r->{LNGE}

The function has to return an arrayref of arrayrefs of the points within the box

tile

Returns the rendered image

AUTHOR

Mark Hofstetter <hofstettm@cpan.org>

Thanks to brian d foy Marcel Gruenauer

TODO

* change to GoogleMaps API v3 * put more magic in calculation of zoom scales * make more things configurable * add even more tests * Rewrite to use Imager http://search.cpan.org/~addi/Imager-0.43/Imager.pm * ...

COPYRIGHT AND LICENSE

This software is copyright (c) 2013 by Mark Hofstetter

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.