Two classes for scraping and viewing met office satellite data

metoffice.rb

# tiny little class to scrape Met Office satellite and radar image feeds and save them
require 'net/http'
require 'ftools'
class MetOfficeGrabber
  def initialize(type, save_folder, file_format='jpg', base_url='http://www.metoffice.gov.uk/weather/images')
    @type = type.to_s # eg ukir_sat or ukvis_sat
    @url = URI.parse(base_url.to_s) # met office website
    @path = save_folder.to_s # save location - will be folderised by type
    @format = file_format.to_s # what format is the file on the website? radar uses gif.
    # make save location if it doesn't exist
    Dir.mkdir(@path) unless File.exists?(@path)
    Dir.mkdir("#{@path}/#{@type}") unless File.exists?("#{@path}/#{@type}")
  end
  def get_image(datetime)
    return false if File.exists?("#{@path}/#{@type}/#{datetime.to_s}.#{@format}") # we've gotten this file..
    begin
      res = Net::HTTP.start(@url.host, @url.port) do |http|
        http.get(@url.path+"/#{@type}_#{datetime.to_s}.#{@format}")
      end
      return true if res.code == "404"
      File.open("#{@path}/#{@type}/#{datetime.to_s}.#{@format}", "wb") do |f|
        f << res.body
      end
      return true
    rescue Exception => e
      puts "Error: Could not retrieve image for #{datetime}, reason: #{e.inspect}"
      return false
    end
  end
  def scrape_latest
    now = Time.now.utc.to_i
    n = 0
    # Walk the last 24 hours
    (0..23).each do |offset|
      break unless get_image(Time.at(now-(3600*offset)).strftime('%Y%m%d%H00'))
      n += 1
    end
    puts "Got #{n.to_s} new images for #{@type.to_s}"
  end
  def scrape_latest_radar
    now = Time.now.utc.to_i
    # Specialised walk for radar
    n = 0
    even = true
    (0..12).each do |offset|
      even ? even = false : even = true
      if even
        break unless get_image(Time.at(now-(1800*offset)).strftime('%Y%m%d%H00'))
      else
        break unless get_image(Time.at(now-(1800*offset)).strftime('%Y%m%d%H30'))
      end
      n += 1
    end
    puts "Got #{n.to_s} new images for #{@type.to_s}"
  end
end

# Scrape the three usual feeds
MetOfficeGrabber.new('ukvis_sat', 'metoffice').scrape_latest
MetOfficeGrabber.new('ukir_sat', 'metoffice').scrape_latest
MetOfficeGrabber.new('uk_britradar', 'metoffice', 'gif').scrape_latest_radar

metoffice_build_gifs.rb

# another little class to grab satellite pics, despeckle and noise-reduce, and package as a GIF image
require 'rubygems'
require 'RMagick'
require 'ftools'
class Animator
  def initialize(path,outfile)
    @i = Magick::ImageList.new
    @i.delay = 200
    Dir.glob(path+"/*").sort{|a,b| a <=> b }.each do |f| 
      puts "Reading "+f.to_s
      img = Magick::Image.read(f)[0]
      puts "Done reading #{f.to_s}, applying filters"
      img = img.enhance
      img = img.despeckle
      @i << img
      puts "Done filtering #{f.to_s}"
    end
    puts "Done! Writing"
    @i.write(outfile)
  end
end
Animator.new("metoffice/ukvis_sat", "vis.gif")
Animator.new("metoffice/ukir_sat", "ir.gif")
Animator.new("metoffice/uk_britradar", "radar.gif")