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坐标偏移问题排查

更新于 写于 GIS

结论

经度偏移大到离谱：

  • 考虑本地坐标系

经度偏移 > 0.006：

经度偏移 > 0.0001 考虑：

处理坐标偏移的工具

js
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;
  }
};

TLDR

WGS-84、北京 54、西安 80 坐标差别：

  • GPS 的测量结果与我国的 54 系或 80 系坐标相差几十米至一百多米，随区域不同，差别也不同，经粗落统计，我国西部相差 70 米左右，东北部 140 米左右，南部 75 米左右，中部 45 米左右。

地理数据加密：

  • 中国大陆所有公开地理数据都需要至少用 GCJ-02 进行加密。

几种坐标：

  • GCJ-02: 高德地图、谷歌地图、腾讯地图
  • BD-09： 百度地图
  • 搜狗坐标：搜狗地图
  • WGS-84：Google Earth（度分秒形式）等

参见