Geoconverter from tile (z,y,zoom), to geodetic coordinates (lat, long) to elliptical mercator UTM in meters (x,y). http://www.maptiler.org/google-maps-coordinates-tile-bounds-projection/ http://wiki.openstreetmap.org/wiki/Slippy_map_tilenames http://wiki.openstreetmap.org/wiki/Mercator

geoconverter

module GeoConverter

	R_MAJOR = 6378137.0 #Equatorial Radius, WGS84
	R_MINOR = 6356752.314245179 #defined as constant

	def to_rad(d)
		d * (Math::PI / 180.0)
	end

	def to_deg(r)
		r / (Math::PI / 180.0)
	end

	class Tile
		include GeoConverter
		attr_reader :x, :y, :z

		def initialize(x, y, z)
			@x, @y, @z = x, y, z
			@nw = LatLon.new( tile2lat(y, z ), tile2long(x,z ) )
			@se = LatLon.new( tile2lat(y + 1, z ), tile2long(x + 1,z ) )
		end
		def north
			@nw.lat
		end
		def west
			@nw.lon
		end
		def south
			@se.lat
		end
		def east
			@se.lon
		end
		def to_boundingBox
			{top: north, left: west, bottom: south, right: east}
		end
		def to_boundingBoxUTM
			puts @nw.to_utm
			tl = Hash[ [:left, :top].zip(@nw.to_utm.values())]
			br = Hash[[:right, :bottom].zip(@se.to_utm.values())]
			tl.merge(br)
		end

		def tile2lat(y, z)
			n = Math::PI - ( 2.0 * Math::PI * y) / (2.0 ** z)
			to_deg( Math.atan( Math.sinh( n ) ) )
		end
		def tile2long(x, z)
			x / (2.0 ** z) * 360.0 -180
		end
	end


	class LatLon
		include GeoConverter
	    attr_reader :lat, :lon
		
	    # Create a new coordinate instance based on latitude and longitude
		def initialize(lat, lon)
		  raise Exception, "Invalid longitude #{lon}" unless (-180.0...180.0).member? lon
		  @lat, @lon = lat, lon
		end

		# Textual representation of the coordinate
		def to_s
		  north_south = if @lat >= 0.0 then 'N' else 'S' end
		  east_west = if @lon >= 0.0 then 'E' else 'W' end
		  '%0.6f%s %0.6f%s' % [@lat.abs, north_south, @lon.abs, east_west]
		end


	    # Convert the coordinate in latutude/longitude into the UTM coordinate system
	    def to_utm()

			x = R_MAJOR * to_rad(@lon)

			@lat = 89.5 if (@lat > 89.5) 
			@lat = -89.5 if (@lat < -89.5)


			temp = R_MINOR / R_MAJOR
			es = 1.0 - (temp * temp)
			eccent = Math.sqrt(es)

			phi = to_rad(@lat)

			sinphi = Math.sin(phi)

			con = eccent * sinphi
			com = 0.5 * eccent
			con2 = ((1.0-con)/(1.0+con)) ** com
			ts = Math.tan(0.5 * (Math::PI*0.5 - phi))/con2
			y = 0 - R_MAJOR * Math.log(ts);
			
			{x: x, y: y}
	    end

	end
end

puts GeoConverter::LatLon.new(60.15244221438077,24.9169921875).to_utm
puts GeoConverter::Tile.new(9326, 4744, 14).to_boundingBox
puts GeoConverter::Tile.new(9326, 4744, 14).to_boundingBoxUTM