谷歌地图离线发布系列之偏移处理（三）纠偏算法

先上代码，用js实现的纠偏算法：

var pi = 3.14159265358979324;

//
// Krasovsky 1940
//
// a = 6378245.0, 1/f = 298.3
// b = a * (1 - f)
// ee = (a^2 - b^2) / a^2;
var a = 6378245.0;
var ee = 0.00669342162296594323;

function outOfChina(lat, lon){
    if (lon < 72.004 || lon > 137.8347)
        return 1;
    if (lat < 0.8293 || lat > 55.8271)
        return 1;
    return 0;
}
function transformLat(x,y){
    var ret = -100.0 + 2.0 * x + 3.0 * y + 0.2 * y * y + 0.1 * x * y + 0.2 * Math.sqrt(x > 0 ? x:-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;
}
function transformLon(x,y){
    var ret = 300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * Math.sqrt(x > 0 ? x:-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;
}
function transformFromWGSToGCJ(wgLoc)
{
    var mgLoc ={};
    mgLoc.lat = 0;
    mgLoc.lng = 0;
    if (outOfChina(wgLoc.lat, wgLoc.lng))
    {
        mgLoc = wgLoc;
        return mgLoc;
    }
    var dLat = transformLat(wgLoc.lng - 105.0, wgLoc.lat - 35.0);
    var dLon = transformLon(wgLoc.lng - 105.0, wgLoc.lat - 35.0);

    var radLat = wgLoc.lat / 180.0 * pi;
    var magic = Math.sin(radLat);
    magic = 1 - ee * magic * magic;
    var sqrtMagic = Math.sqrt(magic);
    dLat = (dLat * 180.0) / ((a * (1 - ee)) / (magic * sqrtMagic) * pi);
    dLon = (dLon * 180.0) / (a / sqrtMagic * Math.cos(radLat) * pi);
    mgLoc.lat = wgLoc.lat + dLat;
    mgLoc.lng = wgLoc.lng + dLon;

    return mgLoc;
}

参考文章1：http://blog.csdn.net/coolypf/article/details/8686588

WGS-84 到 GCJ-02 的转换（即 GPS 加偏）算法是一个普通青年轻易无法接触到的“公开”的秘密。这个算法的代码在互联网上是公开的，详情请使用 Google 搜索 "wgtochina_lb" 。

整理后的算法代码请参考 https://on4wp7.codeplex.com/SourceControl/changeset/view/21483#353936 。知道了这个算法之后，就可以离线进行 Google 地图偏移校正，不必像之前那么麻烦。

至于 GCJ-02 到 WGS-84 的转换（即 GPS 纠偏），可以使用二分法。

参考文章2：http://www.zuidaima.com/code/file/1665077235663872.htm?dir=/correct_lat_lon/src/com/hgq/correct/MapFix.java

package com.hgq.correct;

003

004

005

/**

006	* 经纬度纠偏工具类

007	* [一句话功能简述]

008	* [功能详细描述]

009	* @author PeiYu

010	* @version 1.0, 2012-8-24

011

* @see

012	* @since gframe-v100

013

*/

014	public class MapFix

015

{

016	private double casm_f = 0.0;

017

018	private double casm_rr = 0.0;

019

020	private double casm_t1 = 0.0;

021

022	private double casm_t2 = 0.0;

023

024	private double casm_x1 = 0.0;

025

026	private double casm_x2 = 0.0;

027

028	private double casm_y1 = 0.0;

029

030	private double casm_y2 = 0.0;

031

032	private MapFix()

033

{

034	casm_rr = 0.0;

035	casm_t1 = 0.0;

036	casm_t2 = 0.0;

037	casm_x1 = 0.0;

038	casm_y1 = 0.0;

039	casm_x2 = 0.0;

040	casm_y2 = 0.0;

041	casm_f = 0.0;

042

}

043

044	private static MapFix instance;

045

046	public static MapFix getInstance()

047

{

048	if (instance == null)

049

{

050	instance = new MapFix();

051

}

052	return instance;

053

}

054

055

/**

056

* 纠偏

057	* @param x 经度

058	* @param y 纬度

059	* @return [0]纠偏后经度   [1]纠偏后纬度

060

*/

061	public double[] fix(double x , double y)

062

{

063	double[] res = new double[2];

064

try

065

{

066	double num = x * 3686400.0;

067	double num2 = y * 3686400.0;

068	double num3 = 0.0;

069	double num4 = 0.0;

070	double num5 = 0.0;

071	MapPoint point = wgtochina_lb(1, (int) num, (int) num2, (int) num5, (int) num3, (int) num4);

072	double num6 = point.getX();

073	double num7 = point.getY();

074	num6 /= 3686400.0;

075	num7 /= 3686400.0;

076	res[0] = num6;

077	res[1] = num7;

078

}

079	catch (Exception ex)

080

{

081	System.out.println(ex);

082

}

083	return res;

084

}

085

086	private void IniCasm(double w_time , double w_lng , double w_lat)

087

{

088	casm_t1 = w_time;

089	casm_t2 = w_time;

090	double num = (int) (w_time / 0.357);

091	casm_rr = w_time - (num * 0.357);

092	if (w_time == 0.0)

093

{

094	casm_rr = 0.3;

095

}

096	casm_x1 = w_lng;

097	casm_y1 = w_lat;

098	casm_x2 = w_lng;

099	casm_y2 = w_lat;

100	casm_f = 3.0;

101

}

102

103	private double random_yj()

104

{

105	double num = 314159269.0;

106	double num2 = 453806245.0;

107	casm_rr = (num * casm_rr) + num2;

108	double num3 = (int) (casm_rr / 2.0);

109	casm_rr -= num3 * 2.0;

110	casm_rr /= 2.0;

111	return casm_rr;

112

}

113

114	private double Transform_jy5(double x , double xx)

115

{

116	double num = 6378245.0;

117	double num2 = 0.00669342;

118	double num3 = Math.sqrt(1.0 - ((num2 * yj_sin2(x * 0.0174532925199433)) * yj_sin2(x * 0.0174532925199433)));

119	return ((xx * 180.0) / (((num / num3) * Math.cos(x * 0.0174532925199433)) * 3.1415926));

120

}

121

122	private double Transform_jyj5(double x , double yy)

123

{

124	double num = 6378245.0;

125	double num2 = 0.00669342;

126	double d = 1.0 - ((num2 * yj_sin2(x * 0.0174532925199433)) * yj_sin2(x * 0.0174532925199433));

127	double num4 = (num * (1.0 - num2)) / (d * Math.sqrt(d));

128	return ((yy * 180.0) / (num4 * 3.1415926));

129

}

130

131	private double Transform_yj5(double x , double y)

132

{

133	double num = ((((300.0 + (1.0 * x)) + (2.0 * y)) + ((0.1 * x) * x)) + ((0.1 * x) * y))

134	+ (0.1 * Math.sqrt(Math.sqrt(x * x)));

135	num += ((20.0 * yj_sin2(18.849555921538762 * x)) + (20.0 * yj_sin2(6.283185307179588* x))) * 0.6667;

136	num += ((20.0 * yj_sin2(3.141592653589794 * x)) + (40.0 * yj_sin2(1.0471975511965981* x))) * 0.6667;

137	return (num + (((150.0 * yj_sin2(0.26179938779914952 * x)) + (300.0 * yj_sin2(0.10471975511965979 * x))) * 0.6667));

138

}

139

140	private double Transform_yjy5(double x , double y)

141

{

142	double num = ((((-100.0 + (2.0 * x)) + (3.0 * y)) + ((0.2 * y) * y)) + ((0.1 * x) * y))

143	+ (0.2 * Math.sqrt(Math.sqrt(x * x)));

144	num += ((20.0 * yj_sin2(18.849555921538762 * x)) + (20.0 * yj_sin2(6.283185307179588* x))) * 0.6667;

145	num += ((20.0 * yj_sin2(3.141592653589794 * y)) + (40.0 * yj_sin2(1.0471975511965981* y))) * 0.6667;

146	return (num + (((160.0 * yj_sin2(0.26179938779914952 * y)) + (320.0 * yj_sin2(0.10471975511965979 * y))) * 0.6667));

147

}

148

149	private MapPoint wgtochina_lb(int wg_flag , int wg_lng , int wg_lat , int wg_heit , int wg_week , int wg_time)

150

{

151	MapPoint point = null;

152	if (wg_heit <= 0x1388)

153

{

154	double num = wg_lng;

155	num /= 3686400.0;

156	double x = wg_lat;