The conversion _javascript technique between Baidu coordinates (BD09), national survey coordinates (MARS coordinates, GCJ02), and WGS84 coordinates

In the project to face a different coordinate system, on the map to show more or less will be somewhat biased, the following is the use of JavaScript to write the conversion method, the specific code as follows:

　Define some constants var X_pi = 3.14159265358979324 * 3000.0/180.0;
　　var PI = 3.1415926535897932384626;
　　var a = 6378245.0;
　　var ee = 0.00669342162296594323; /** * Baidu coordinate system (BD-09) and the Mars coordinate system (GCJ-02) conversion * That is, Baidu to Google, Gould * @param bd_lon * @param bd_lat * @returns {*[]}/F
　　Unction bd09togcj02 (Bd_lon, Bd_lat) {var x_pi = 3.14159265358979324 * 3000.0/180.0;
　　var x = bd_lon-0.0065;
　　var y = bd_lat-0.006;
　　var z = math.sqrt (x * x + y * y)-0.00002 * Math.sin (y * x_pi);
　　var theta = math.atan2 (y, x)-0.000003 * MATH.COS (x * x_pi);
　　var gg_lng = z * Math.Cos (theta);
　　var Gg_lat = z * Math.sin (theta); return [GG_LNG, Gg_lat]}/** * Mars coordinate system (GCJ-02) and Baidu coordinate system (BD-09) conversion * Namely Google, high Tak to Baidu * @param LNG * @param lat * @returns {*[ ] */function gcj02tobd09 (LNG, lat) {var z = math.sqrt (LNG * LNG + lat * lat) + 0.00002 * Math.sin (LAT * x_pi); var
TA = math.atan2 (lat, LNG) + 0.000003 * Math.Cos (LNG * x_pi);
var bd_lng = z * Math.Cos (theta) + 0.0065; var Bd_lat = Z * math.sin(theta) + 0.006; return [BD_LNG, Bd_lat]}/** * WGS84 GCj02 * @param LNG * @param lat * @returns {*[]}/function wgs84togcj02 (LNG, LAT) {if (Out_of_china (LNG, LAT)) {return [LNG, LAT]} else {var Dlat = Transformlat (lng-105.0, lat-35.0); var dlng = t
RANSFORMLNG (lng-105.0, lat-35.0);
var Radlat = 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);
DLNG = (DLNG * 180.0)/(A/sqrtmagic * MATH.COS (Radlat) * PI);
var Mglat = lat + Dlat;
var mglng = lng + dlng; return [MGLNG, Mglat]}/** * GCJ02 conversion to WGS84 * @param LNG * @param lat * @returns {*[]}/function Gcj02towgs84 (LNG, L  at) {if (Out_of_china (LNG, LAT)) {return [LNG, LAT]} else {var Dlat = Transformlat (lng-105.0, lat-35.0); var dlng
= TRANSFORMLNG (lng-105.0, lat-35.0);
var Radlat = 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);
DLNG = (DLNG * 180.0)/(A/sqrtmagic * MATH.COS (Radlat) * PI);
Mglat = lat + Dlat;
MGLNG = LNG + dlng; return [LNG * 2-mglng, LAT * 2-mglat]}} function Transformlat (LNG, LAT) {var ret = -100.0 + 2.0 * LNG + 3.0 * LAT
+ 0.2 * lat * lat + 0.1 * LNG * LAT + 0.2 * MATH.SQRT (Math.Abs (LNG));
RET + = (20.0 * Math.sin (6.0 * LNG * pi) + 20.0 * Math.sin (2.0 * LNG * pi)) * 2.0/3.0;
RET = = (20.0 * Math.sin (lat * pi) + 40.0 * Math.sin (lat/3.0 * pi)) * 2.0/3.0;
ret = = (160.0 * Math.sin (lat/12.0 * PI) + math.sin (lat * pi/30.0)) * 2.0/3.0; return ret} function transformlng (LNG, LAT) {var ret = 300.0 + LNG + 2.0 * LAT + 0.1 * LNG * LNG + 0.1 * LNG * LAT + 0.
1 * MATH.SQRT (Math.Abs (LNG));
RET + = (20.0 * Math.sin (6.0 * LNG * pi) + 20.0 * Math.sin (2.0 * LNG * pi)) * 2.0/3.0;
RET + + (20.0 * Math.sin (LNG * pi) + 40.0 * Math.sin (lng/3.0 * pi)) * 2.0/3.0; RET + = (150.0 * Math.sin (LNG/12.0 * pi) + 300.0 * Math.sin (lng/30.0 * pi)) * 2.0/3.0; 
return ret}/** * To determine whether at home, not at home do not offset * @param LNG * @param lat * @returns {Boolean}/function Out_of_china (LNG, LAT) { Return (LNG < 72.004 | | LNG > 137.8347) | |
(Lat < 0.8293 | | | lat > 55.8271) | | false);
///Use example//GPS coordinates to Mars coordinate var lng_lat_1 = wgs84togcj02 (113.912743,22.497629);
Console.log (' Mars coordinates ... ', lng_lat_1);
Mars coordinates to Baidu coordinate var lng_lat_2 = gcj02tobd09 (Lng_lat_1[0], lng_lat_1[1]); Console.log (' Baidu coordinates ... ', lng_lat_2);