将 EPSG3035 转换为 EPSG3857 墨卡托或 4326 LonLat

Question

直接在 JavaScript 中处理一个 geojson 文件，我找不到任何简单的方法将我的坐标从 EPSG3035 转换为地理坐标（Lon，Lat）。 我的意思是简单：不安装其他软件，如 QGIS 或类似软件。 我试过 proj4 和 ol，但都失败了。

我没有任何线索。 [OL 解决方案在下面的“t.niese”答案中]

 let coordinates = [4035675.373507705517113, 2862363.090465864632279]; // Luxembourg console.log(coordinates); // a "well-known text" WKT-OGC definition from https://epsg.io/3035 const WKT3035 = `PROJCS["ETRS89 / LAEA Europe",GEOGCS["ETRS89",DATUM["European_Terrestrial_Reference_System_1989",SPHEROID["GRS 1980",6378137,298.257222101,AUTHORITY["EPSG","7019"]],TOWGS84[0,0,0,0,0,0,0],AUTHORITY["EPSG","6258"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4258"]],PROJECTION["Lambert_Azimuthal_Equal_Area"],PARAMETER["latitude_of_center",52],PARAMETER["longitude_of_center",10],PARAMETER["false_easting",4321000],PARAMETER["false_northing",3210000],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AUTHORITY["EPSG","3035"]]`; // trying OpenLayers try { const fromLonLat = ol.proj.getTransform("EPSG:3035", "EPSG:4326"); coordinates = fromLonLat(coordinates); console.log("using ol.proj", coordinates); } catch (err) { console.error(err) } try { // trying proj4 coordinates = [4035675.373507705517113, 2862363.090465864632279]; const srcProj = new proj4.Proj(WKT3035); proj4(srcProj).inverse(coordinates); console.log("using proj4", coordinates); } catch (err) { console.error(err) }

 <script src="https://cdn.jsdelivr.net/gh/openlayers/openlayers.github.io@master/en/v6.8.1/build/ol.js"></script> <script src="https://cdnjs.cloudflare.com/ajax/libs/proj4js/2.7.5/proj4.js"></script>

Answer 1

你得到的错误是因为 proj4 不知道投影EPSG:3035

如果您运行console.log(proj4.defs('EPSG:3035'))您可以看到它返回undefined 。

 console.log(proj4.defs('EPSG:3035'))

 <script src="https://cdn.jsdelivr.net/gh/openlayers/openlayers.github.io@master/en/v6.8.1/build/ol.js"></script> <script src="https://cdnjs.cloudflare.com/ajax/libs/proj4js/2.7.5/proj4.js"></script>

如果您只使用proj4 ，您可以使用以下方法定义投影：

proj4.defs("EPSG:3035", /* here goes the definition of that projection */);

使用proj4.defs(name, definition)不返回任何内容，它定义了具有该名称的投影，以便它可以与该名称一起使用。 定义投影后，您可以使用proj4.defs(name)来获取它。

如果对于 OpenLayer，您还需要在之后注册proj4 ：

proj4.defs("EPSG:3035", /* here goes the definition of that projection */);
ol.proj.proj4.register(proj4);

proj4的定义应该是+proj=laea +lat_0=52 +lon_0=10 +x_0=4321000 +y_0=3210000 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs （来源https://epsg.io/3035 ）

 proj4.defs("EPSG:3035", '+proj=laea +lat_0=52 +lon_0=10 +x_0=4321000 +y_0=3210000 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs'); ol.proj.proj4.register(proj4); let coordinates = [4035675.373507705517113, 2862363.090465864632279]; // Luxembourg console.log(coordinates); try { // trying OpenLayers const fromLonLat = ol.proj.getTransform("EPSG:3035", "EPSG:4326"); console.dir(fromLonLat(coordinates)); } catch (err) { console.error(err) } try { // trying proj4 console.dir(proj4(proj4.defs('EPSG:3035'), proj4.defs('EPSG:4326'), coordinates)); } catch (err) { console.error(err) }

 <script src="https://cdn.jsdelivr.net/gh/openlayers/openlayers.github.io@master/en/v6.8.1/build/ol.js"></script> <script src="https://cdnjs.cloudflare.com/ajax/libs/proj4js/2.7.5/proj4.js"></script>