source: src/django_gheat/gheat/management/commands/gen_tiles.py

###############################################################################
#Management command to generate tiles using gheat.
#
#Must be given a bounding box by using options -s and -e (start and end)
#
#Example usage:
#>>> python manage.py gen_tiles -s 60,6 -e 66,8 -c firetrans -b serve_tile
#
#Note: This command will NOT create tiles if they are empty. In order to do so, change
#the gheat generate_tile view so that it creates empty tiles for each request given
#x and y and zoom. This way you wan't have "holes" in the tile overlay if using
#the static tiles instead of the usual django url/view.
#
#Author: Dennis Wagenaar
#
#Original Author: Anders Eriksen
#https://github.com/robertrv/django-gheat/issues/1
#
###############################################################################

from django.core.management.base import BaseCommand
from optparse import OptionParser, make_option
from django.core.urlresolvers import reverse
from django.test.client import Client
import math

class LatLonToTile:

  def deg2num(self, lat_deg, lon_deg, zoom):
    lat_rad = math.radians(lat_deg)
    n = 2.0 ** zoom
    xtile = int((lon_deg + 180.0) / 360.0 * n)
    ytile = int((1.0 - math.log(math.tan(lat_rad) + (1 / math.cos(lat_rad))) / math.pi) / 2.0 * n)
    return(xtile, ytile)


class Command(BaseCommand):

  option_list = BaseCommand.option_list + (
    make_option("-b", "--tileview", dest="viewname", default="serve_tile"),
    make_option("-s", "--start", dest="start", default="52.132708,4.437389"),
    make_option("-e", "--end", dest="end", default="52.178837,4.551029"),
    make_option("-c", "--colorscheme", dest="color", default="classic"),
  )

  def handle(self, *args, **options):
    start = options['start'].split(',')
    end = options['end'].split(',')
    viewname = options['viewname']
    colorscheme = str(options['color'])

    d2n = LatLonToTile()

    #initialize browser client
    c = Client()
    from gheat.models import MeetRondje
 #   collection = MeetRondje.objects.values('naam')
#    for col in collection:
    for tz in range(1, 22):
      #calculate start tiles
      mxmin, mymax = d2n.deg2num(float(start[0]), float(start[1]), tz)

      #calculate end tiles
      mxmax, mymin = d2n.deg2num(float(end[0]), float(end[1]), tz)

      #loop through each tile and generate a request to the serve_tile view using Client
      for ty in range(mymin, mymax+1):
        for tx in range(mxmin, mxmax+1):
          tileurl = reverse(viewname, kwargs={'color_scheme': colorscheme, 'zoom':tz, 'x':tx, 'y':ty})
          generate_response = c.get(tileurl)
          #lousy error handling. Should check why status 200 not returned... I.e. wrong colorscheme
          if generate_response.status_code == 200:
            print "Generated tile " + tileurl
          else:
            print "Failed generating tile " + tileurl