本文主要是记录用到的各类GPS坐标(WGS-84、GCJ-02(高德)、BD-09(百度))的相互转换方法,为JavaScript版本,主要借鉴来源该篇CSDN文章。
官方转换接口 高德、百度等各自都有自己的坐标转换API,但是每次请求都存在延迟,相对较麻烦。
高德转换API。 百度转换API。
它们各自的JS版SDK中存在的转换函数,基本都是异步处理,前端处理时经常会碰到不方便的情况,所以有了本文。
高德坐标转换方法。
本地转换代码 该算法精度保证到小数点后6位,精度符合高德、百度地图的精度范围。
var GPS = { PI: 3.14159265358979324, x_pi: 3.14159265358979324 * 3000.0 / 180.0, delta: function(lon, lat) { 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 { 'lon': dLon, 'lat': dLat } }, // WGS-84 to GCJ-02 gcj_encrypt: function(wgsLon, wgsLat) { if (this.outOfChina(wgsLon, wgsLat)) { console.log('outOfChina') return {'lon': wgsLon, 'lat': wgsLat } } var d = this.delta(wgsLon, wgsLat) return { 'lon': wgsLon + d.lon, 'lat': wgsLat + d.lat } }, // GCJ-02 to WGS-84 gcj_decrypt: function(gcjLon, gcjLat) { if (this.outOfChina(gcjLon, gcjLat)) { return { 'lon': gcjLon, 'lat': gcjLat } } var d = this.delta(gcjLat, gcjLon) return { 'lon': gcjLon - d.lon, 'lat': gcjLat - d.lat } }, // GCJ-02 to WGS-84 exactly gcj_decrypt_exact: function(gcjLon, gcjLat) { var initDelta = 0.01 var threshold = 0.000000001 var dLat = initDelta var dLon = initDelta var mLat = gcjLat - dLat var mLon = gcjLon - dLon var pLat = gcjLat + dLat var pLon = gcjLon + dLon var wgsLat, wgsLon var i = 0 // eslint-disable-next-line while (i) { 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 } } return { 'lon': wgsLon, 'lat': wgsLat } }, // GCJ-02 to BD-09 bd_encrypt: function(gcjLon, gcjLat) { var x = gcjLon var 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) var bdLon = z * Math.cos(theta) + 0.0065 var bdLat = z * Math.sin(theta) + 0.006 return { 'lon': bdLon, 'lat': bdLat } }, // BD-09 to GCJ-02 bd_decrypt: function(bdLon, bdLat) { var x = bdLon - 0.0065 var 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 { 'lon': gcjLon, 'lat': gcjLat } }, // WGS-84 to Web mercator // mercatorLat -> y mercatorLon -> x mercator_encrypt: function(wgsLon, wgsLat) { var x = wgsLon * 20037508.34 / 180.0 var y = Math.log(Math.tan((90.0 + wgsLat) * this.PI / 360.0)) / (this.PI / 180.0) y = y * 20037508.34 / 180.0 return { 'lon': x, ' lat': y } }, // Web mercator to WGS-84 // mercatorLat -> y mercatorLon -> x mercator_decrypt: function(mercatorLon, mercatorLat) { var x = mercatorLon / 20037508.34 * 180.0 var y = mercatorLat / 20037508.34 * 180.0 y = 180 / this.PI * (2 * Math.atan(Math.exp(y * this.PI / 180.0)) - this.PI / 2) return { 'lon': x, 'lat': y } }, // two point's distance distance: function(lonA, latA, lonB, latB) { var earthR = 6371000.0 var x = Math.cos(latA * this.PI / 180.0) * Math.cos(latB * this.PI / 180.0) * Math.cos((lonA - lonB) * this.PI / 180.0) var y = Math.sin(latA * this.PI / 180.0) * Math.sin(latB * this.PI / 180.0) 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 outOfChina: function(lon, lat) { 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 } } export default GPS