WGS-84：是国际标准，GPS坐标（Google Earth使用、或者GPS模块）GCJ-02：中国坐标偏移标准，Google Map、高德、腾讯使用BD-09：百度坐标偏移标准，Baidu Map使用//WGS-84 to GCJ-02GPS.gcj_encrypt();//GCJ-02 to WGS-84 粗略GPS.gcj_decrypt();//GCJ-02 to WGS-84 精确(二分极限法)// var threshold = 0.000000001; 目前设置的是精确到小数点后9位，这个值越小，越精确，但是javascript中，浮点运算本身就不太精确，九位在GPS里也偏差不大了GSP.gcj_decrypt_exact();//GCJ-02 to BD-09GPS.bd_encrypt();//BD-09 to GCJ-02GPS.bd_decrypt();//求距离GPS.distance();示例：document.write("GPS: 39.933676862706776,116.35608315379092<br />");var arr2 = GPS.gcj_encrypt(39.933676862706776, 116.35608315379092);document.write("中国:" + arr2['lat']+","+arr2['lon']+'<br />');var arr3 = GPS.gcj_decrypt_exact(arr2['lat'], arr2['lon']);document.write('逆算:' + arr3['lat']+","+arr3['lon']+' 需要和第一行相似（目前是小数点后9位相等）');
JavaScript代码
var GPS = { PI : 3.14159265358979324, x_pi : 3.14159265358979324 * 3000.0 / 180.0, delta : function (lat, lon) { // Krasovsky 1940 // // a = 6378245.0, 1/f = 298.3 // b = a * (1 - f) // ee = (a^2 - b^2) / a^2; var a = 6378245.0; // a: 卫星椭球坐标投影到平面地图坐标系的投影因子。 var ee = 0.00669342162296594323; // ee: 椭球的偏心率。 var dLat = this .transformLat(lon - 105.0, lat - 35.0); var dLon = this .transformLon(lon - 105.0, lat - 35.0); var radLat = lat / 180.0 * this .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) * this .PI); dLon = (dLon * 180.0) / (a / sqrtMagic * Math.cos(radLat) * this .PI); return { 'lat' : dLat, 'lon' : dLon}; }, //WGS-84 to GCJ-02 gcj_encrypt : function (wgsLat, wgsLon) { if ( this .outOfChina(wgsLat, wgsLon)) return { 'lat' : wgsLat, 'lon' : wgsLon}; var d = this .delta(wgsLat, wgsLon); return { 'lat' : wgsLat + d.lat, 'lon' : wgsLon + d.lon}; }, //GCJ-02 to WGS-84 gcj_decrypt : function (gcjLat, gcjLon) { if ( this .outOfChina(gcjLat, gcjLon)) return { 'lat' : gcjLat, 'lon' : gcjLon}; var d = this .delta(gcjLat, gcjLon); return { 'lat' : gcjLat - d.lat, 'lon' : gcjLon - d.lon}; }, //GCJ-02 to WGS-84 exactly gcj_decrypt_exact : function (gcjLat, gcjLon) { var initDelta = 0.01; var threshold = 0.000000001; var dLat = initDelta, dLon = initDelta; var mLat = gcjLat - dLat, mLon = gcjLon - dLon; var pLat = gcjLat + dLat, pLon = gcjLon + dLon; var wgsLat, wgsLon, i = 0; while (1) { wgsLat = (mLat + pLat) / 2; wgsLon = (mLon + pLon) / 2; var tmp = this .gcj_encrypt(wgsLat, wgsLon) dLat = tmp.lat - gcjLat; dLon = tmp.lon - gcjLon; if ((Math.abs(dLat) < threshold) && (Math.abs(dLon) < threshold)) break ; if (dLat > 0) pLat = wgsLat; else mLat = wgsLat; if (dLon > 0) pLon = wgsLon; else mLon = wgsLon; if (++i > 10000) break ; } //console.log(i); return { 'lat' : wgsLat, 'lon' : wgsLon}; }, //GCJ-02 to BD-09 bd_encrypt : function (gcjLat, gcjLon) { var x = gcjLon, y = gcjLat; var z = Math.sqrt(x * x + y * y) + 0.00002 * Math.sin(y * this .x_pi); var theta = Math.atan2(y, x) + 0.000003 * Math.cos(x * this .x_pi); bdLon = z * Math.cos(theta) + 0.0065; bdLat = z * Math.sin(theta) + 0.006; return { 'lat' : bdLat, 'lon' : bdLon}; }, //BD-09 to GCJ-02 bd_decrypt : function (bdLat, bdLon) { var x = bdLon - 0.0065, y = bdLat - 0.006; var z = Math.sqrt(x * x + y * y) - 0.00002 * Math.sin(y * this .x_pi); var theta = Math.atan2(y, x) - 0.000003 * Math.cos(x * this .x_pi); var gcjLon = z * Math.cos(theta); var gcjLat = z * Math.sin(theta); return { 'lat' : gcjLat, 'lon' : gcjLon}; }, //WGS-84 to Web mercator //mercatorLat -> y mercatorLon -> x mercator_encrypt : function (wgsLat, wgsLon) { var x = wgsLon * 20037508.34 / 180.; var y = Math.log(Math.tan((90. + wgsLat) * this .PI / 360.)) / ( this .PI / 180.); y = y * 20037508.34 / 180.; return { 'lat' : y, 'lon' : x}; /* if ((Math.abs(wgsLon) > 180 || Math.abs(wgsLat) > 90)) return null; var x = 6378137.0 * wgsLon * 0.017453292519943295; var a = wgsLat * 0.017453292519943295; var y = 3189068.5 * Math.log((1.0 + Math.sin(a)) / (1.0 - Math.sin(a))); return {'lat' : y, 'lon' : x}; //*/ }, // Web mercator to WGS-84 // mercatorLat -> y mercatorLon -> x mercator_decrypt : function (mercatorLat, mercatorLon) { var x = mercatorLon / 20037508.34 * 180.; var y = mercatorLat / 20037508.34 * 180.; y = 180 / this .PI * (2 * Math.atan(Math.exp(y * this .PI / 180.)) - this .PI / 2); return { 'lat' : y, 'lon' : x}; /* if (Math.abs(mercatorLon) < 180 && Math.abs(mercatorLat) < 90) return null; if ((Math.abs(mercatorLon) > 20037508.3427892) || (Math.abs(mercatorLat) > 20037508.3427892)) return null; var a = mercatorLon / 6378137.0 * 57.295779513082323; var x = a - (Math.floor(((a + 180.0) / 360.0)) * 360.0); var y = (1.5707963267948966 - (2.0 * Math.atan(Math.exp((-1.0 * mercatorLat) / 6378137.0)))) * 57.295779513082323; return {'lat' : y, 'lon' : x}; //*/ }, // two point's distance distance : function (latA, lonA, latB, lonB) { var earthR = 6371000.; var x = Math.cos(latA * this .PI / 180.) * Math.cos(latB * this .PI / 180.) * Math.cos((lonA - lonB) * this .PI / 180); var y = Math.sin(latA * this .PI / 180.) * Math.sin(latB * this .PI / 180.); var s = x + y; if (s > 1) s = 1; if (s < -1) s = -1; var alpha = Math.acos(s); var distance = alpha * earthR; return distance; }, outOfChina : function (lat, lon) { if (lon < 72.004 || lon > 137.8347) return true ; if (lat < 0.8293 || lat > 55.8271) return true ; return false ; }, transformLat : function (x, y) { var 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 * this .PI) + 20.0 * Math.sin(2.0 * x * this .PI)) * 2.0 / 3.0; ret += (20.0 * Math.sin(y * this .PI) + 40.0 * Math.sin(y / 3.0 * this .PI)) * 2.0 / 3.0; ret += (160.0 * Math.sin(y / 12.0 * this .PI) + 320 * Math.sin(y * this .PI / 30.0)) * 2.0 / 3.0; return ret; }, transformLon : function (x, y) { var 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 * this .PI) + 20.0 * Math.sin(2.0 * x * this .PI)) * 2.0 / 3.0; ret += (20.0 * Math.sin(x * this .PI) + 40.0 * Math.sin(x / 3.0 * this .PI)) * 2.0 / 3.0; ret += (150.0 * Math.sin(x / 12.0 * this .PI) + 300.0 * Math.sin(x / 30.0 * this .PI)) * 2.0 / 3.0; return ret; } };
转载于:https://www.cnblogs.com/jym-sunshine/p/5542825.html
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