3857墨卡托坐标系转换为4326 (WGS84)经纬度坐标

mercatorTolonlat(mercator) {
  var lonlat = [0, 0]
  var x = mercator[0] / 20037508.34 * 180
  var y = mercator[1] / 20037508.34 * 180
  y = 180 / Math.PI * (2 * Math.atan(Math.exp(y * Math.PI / 180)) - Math.PI / 2)
  lonlat[0] = x
  lonlat[1] = y
  return lonlat
}

地理坐标系4326–投影坐标系3857/2436

空间参考坐标系查询网址:https://spatialreference.org/和http://epsg.io/

EPSG:4326 (WGS84) 地理坐标系,WGS84 是目前最流行的地理坐标系统。在国际上,每个坐标系统都会被分配一个 EPSG 代码,EPSG:4326 就是 WGS84 的代码。
GPS是基于WGS84的,所以通常我们得到的坐标数据都是WGS84的。一般存储数据时,仍然按WGS84存储。

EPSG:3857 (Pseudo-Mercator) 伪墨卡托投影,也被称为球体墨卡托,Web Mercator。它是基于墨卡托投影的,把 WGS84坐标系投影到正方形上。

EPSG:2436,北京范围的投影坐标系;
北京的东西范围:Beijing: 115.7°E - 117.4°E;
Beijing 1954 / 3-degree Gauss-Kruger CM 117E (Google it);
WGS84 Bounds: 115.5000, 22.6600, 118.5000, 49.8800;
Projected Bounds: 345818.6654, 2507707.7737, 654181.3346, 5528676.1748;
Scope: Large scale topographic mapping, cadastral and engineering survey.;
Last Revised: July 22, 2006;
Area: China - 115.5°E to 118.5°E.

查询与北京/中国有关的坐标系

SELECT * FROM spatial_ref_sys WHERE srtext ~* 'beijing';

SELECT * FROM spatial_ref_sys WHERE srtext ~* 'china';

SELECT ST_AsText(ST_Transform(ST_GeomFromText('POLYGON((743238 2967416,743238 2967450,743265 2967450,743265.625 2967416,743238 2967416))',2249),4326)) As wgs_geom;

SELECT ST_AsEWKT(ST_Transform(ST_GeomFromEWKT('SRID=2249;CIRCULARSTRING(743238 2967416 1,743238 2967450 2,743265 2967450 3,743265.625 2967416 3,743238 2967416 4)'),4326));

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