Conversion between Baidu coordinate (BD09), National Bureau coordinate (Mars coordinate, GCJ02), and WGS84 coordinate system _ javascript skills

This article mainly introduces the conversion data between Baidu coordinates (BD09), the space test Bureau coordinates (Mars coordinates, GCJ02), and the WGS84 coordinate system, you can refer to different coordinate systems in the project to see if the map shows a little different. The following is a conversion method written in javascript. The specific code is 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) conversion to the Mars coordinate system (GCJ-02) * Baidu to Google, autonavi * @ param bd_lon * @ param bd_lat * @ returns {* []} */function 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 of * Is Google, autonavi 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 theta = 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 to 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 = transformlng (lng-105.0, lat-35.0); var radlat = lat/180.0 * PI; var magic = Math. sin (radlat); magic = 1-ee * 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 to WGS84 * @ param lng * @ param lat * @ returns {* []} */function gcj02towgs84 (lng, lat) {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; 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 + 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) + 320 * 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 + 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}/*** determines whether it is in China, if you are not in China, no 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 // convert the gps coordinate to the Mars coordinate var lng_lat_1 = wgs84togcj02 (113.912743, 22.497629 ); console. log ('Mars coordinate... ', lng_lat_1); // convert the Mars coordinate to the Baidu coordinate var lng_lat_2 = gcj02tobd09 (lng_lat_1 [0], lng_lat_1 [1]); console. log ('Baidu coordinate... ', lng_lat_2 );