Vodaphone 3G tile scraper configured for UK coordinates

vodaphone_3g.rb

require 'rubygems'
require 'open-uri'
require 'fileutils'
require 'rio'

xmin = 102728.5
xmax = 458539.5
ymin = 20753.4117647059
ymax = 219318

xsize = xmax-xmin
ysize = ymax-ymin

x_tile = 2
y_tile = 5

y_tile.times do |y|
  @ymn = ymin + (ysize * y+1)
  @ymx = ymax + (ysize * y+1)

  x_tile.times do |x|
    @xmn = xmin + (xsize * x+1)
    @xmx = xmax + (xsize * x+1)
    
    puts "(#{@xmn},#{@ymn}) (#{@xmx},#{@ymx})"
    
    url = "http://83.245.79.115/coverageviewer/web/Map.aspx?XMIN=#{@xmn}&YMIN=#{@ymn}&XMAX=#{@xmx}&YMAX=#{@ymx}&WIDTH=1300&HEIGHT=800&service=GB&mode=postcode&modeValue=1541818&searchEasting=435634&searchNorthing=219318&searchMapService=GB&searchType=postcode&activeLayer=ys3g_no2g&scale=6"

   rio("#{url}") > rio("tmp/#{x}_#{y}.jpg")
  end
end