Ref:
GCJ-02 (火星坐標) 轉 BD-09 (百度坐標) 的算法
http://www.xcoder.cn/html/mobile/iOS/2013/0315/2394.html
eviltransform.cs (WGS-84 地球坐標轉 GCJ-02 火星坐標的C#代碼)
https://on4wp7.codeplex.com/SourceControl/changeset/view/21483#353936
英文詳盡解釋
http://www.sinosplice.com/life/archives/2013/07/16/a-more-complete-ios-solution-to-the-china-gps-offset-problem
Eviltransform.cs
// // Copyright (C) 1000 - 9999 Somebody Anonymous // NO WARRANTY OR GUARANTEE // using System; namespace Navi { class EvilTransform { const double pi = 3.14159265358979324; // // Krasovsky 1940 // // a = 6378245.0, 1/f = 298.3 // b = a * (1 - f) // ee = (a^2 - b^2) / a^2; const double a = 6378245.0; const double ee = 0.00669342162296594323; // // World Geodetic System ==> Mars Geodetic System public static void transform(double wgLat, double wgLon, out double mgLat, out double mgLon) { if (outOfChina(wgLat, wgLon)) { mgLat = wgLat; mgLon = wgLon; return; } double dLat = transformLat(wgLon - 105.0, wgLat - 35.0); double dLon = transformLon(wgLon - 105.0, wgLat - 35.0); double radLat = wgLat / 180.0 * pi; double magic = Math.Sin(radLat); magic = 1 - ee * magic * magic; double sqrtMagic = Math.Sqrt(magic); dLat = (dLat * 180.0) / ((a * (1 - ee)) / (magic * sqrtMagic) * pi); dLon = (dLon * 180.0) / (a / sqrtMagic * Math.Cos(radLat) * pi); mgLat = wgLat + dLat; mgLon = wgLon + dLon; } static bool outOfChina(double lat, double lon) { if (lon < 72.004 || lon > 137.8347) return true; if (lat < 0.8293 || lat > 55.8271) return true; return false; } static double transformLat(double x, double y) { double ret = -100.0 + 2.0 * x + 3.0 * y + 0.2 * y * y + 0.1 * x * y + 0.2 * Math.Sqrt(Math.Abs(x)); ret += (20.0 * Math.Sin(6.0 * x * pi) + 20.0 * Math.Sin(2.0 * x * pi)) * 2.0 / 3.0; ret += (20.0 * Math.Sin(y * pi) + 40.0 * Math.Sin(y / 3.0 * pi)) * 2.0 / 3.0; ret += (160.0 * Math.Sin(y / 12.0 * pi) + 320 * Math.Sin(y * pi / 30.0)) * 2.0 / 3.0; return ret; } static double transformLon(double x, double y) { double ret = 300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * Math.Sqrt(Math.Abs(x)); ret += (20.0 * Math.Sin(6.0 * x * pi) + 20.0 * Math.Sin(2.0 * x * pi)) * 2.0 / 3.0; ret += (20.0 * Math.Sin(x * pi) + 40.0 * Math.Sin(x / 3.0 * pi)) * 2.0 / 3.0; ret += (150.0 * Math.Sin(x / 12.0 * pi) + 300.0 * Math.Sin(x / 30.0 * pi)) * 2.0 / 3.0; return ret; } } }
