Here you can find the source of pixelSize(double lat, double lng, int zoom)
public static double pixelSize(double lat, double lng, int zoom)
//package com.java2s; /*/*from www. j a va 2 s . c om*/ * ProjectionUtil.java * * Copyright 2008 Tommi Laukkanen * http://www.substanceofcode.com * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA * */ public class Main { private static final int TILE_SIZE = 256; public static double pixelSize(double lat, double lng, int zoom) { double scale = (1 << zoom) * TILE_SIZE; return 40075160 * Math.cos(Math.PI * lat / 180) / scale; } }