Downloads and stitches map tiles

TileSticher.cs

using System;
using System.Net;
using System.IO;
using Gdk;

namespace TileSticher
{
	class App
	{
		public static int Main (string[] args)
		{
			if (args.Length != 5) {
				Console.WriteLine ("TileSticher.exe latitude longitude zoom numHorizontal numVertical");
				return 1;
			}

			//
			// Get the root tile
			//
			var latitude = double.Parse (args [0]);
			var longitude = double.Parse (args [1]);
			var zoom = int.Parse (args [2]);
			var numHorizontal = int.Parse (args [3]);
			var numVertical = int.Parse (args [4]);

			var t = GetTileIndex (latitude, longitude, zoom);

			//
			// Download all the tiles
			//
			var style = SatelliteUrlTemplate;
			var xo = -numHorizontal / 2;
			var yo = -numVertical / 2;
			for (var i = 0; i < numHorizontal; i++) {
				for (var j = 0; j < numVertical; j++) {
					var index = new Point (t.X + i + xo, t.Y + j + yo);
					DownloadTile (style, index, zoom);
				}
			}

			//
			// Merge them
			//
			var rootImage = LoadTile (style, t, zoom);
			var width = rootImage.Width;
			var height = rootImage.Height;
			var outputWidth = width * numHorizontal;
			var outputHeight = height * numVertical;
			var output = new Pixbuf (Colorspace.Rgb, false, 8, outputWidth, outputHeight);
			for (var i = 0; i < numHorizontal; i++) {
				for (var j = 0; j < numVertical; j++) {
					var index = new Point (t.X + i + xo, t.Y + j + yo);
					using (var image = LoadTile (style, index, zoom)) {
						image.Composite (
							output, 
							width * i, height * j, 
							width, height,
							width * i, height * j,
							1, 1,
							InterpType.Bilinear, 255);
					}
				}
			}

			output.Save ("Poop.png", "png");

			Console.WriteLine ("Created {0}x{1} Poop.png", outputWidth, outputHeight);

			return 0;
		}

		static Pixbuf LoadTile (string style, Point index, int zoom)
		{
			return new Pixbuf (GetTileFilename (style, index, zoom));
		}

		static string GetTileFilename (string style, Point index, int zoom)
		{
			return string.Format ("{0}-{1}-{2}-{3}.png", index.X, index.Y, zoom, style.Length);
		}

		static void DownloadTile (string style, Point index, int zoom)
		{
			var filename = GetTileFilename (style, index, zoom);

			if (File.Exists (filename))
				return;

			var url = string.Format (style, index.X, index.Y, zoom);
			Console.WriteLine ("Downloading {0}", url);

			var web = new WebClient ();
			web.Headers.Add ("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; .NET CLR 1.0.3705;)");
			web.DownloadFile (url, filename);
		}

		const string MapUrlTemplate = "https://www.google.com/maps/vt/pb=!1m4!1m3!1i{2}!2i{0}!3i{1}!2m3!1e0!2sm!3i258145710";
		const string SatelliteUrlTemplate = "https://khms2.google.com/kh/v=147&x={0}&y={1}&z={2}";

		static Point GetTileIndex (double latitude, double longitude, int zoom)
		{
			var lat_rad = latitude / 180 * Math.PI;
			var n = 1 << zoom;
			var xtile = n * ((longitude + 180) / 360);
			var ytile = n * (1 - (Math.Log (Math.Tan (lat_rad) + 1/Math.Cos (lat_rad)) / Math.PI)) / 2;
			return new Point ((int)xtile, (int)ytile);
		}
	}
}