javascript 将地理 WGS 84 转换为 Web Mercator 102100
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Converting geographic WGS 84 to Web Mercator 102100
提问by
I am trying to convert geographic coordinate system to Esri Webmercator, but when I do the conversion the resulted x and y have values of 0000003232112222… and 00000012665321…. This is very odd since coordinates as those do not exist.
我正在尝试将地理坐标系转换为 Esri Webmercator，但是当我进行转换时，结果 x 和 y 的值为 0000003232112222... 和 00000012665321...。这很奇怪，因为坐标不存在。
var positions = [];
positions.push(x, y);
var g = new esri.geometry.Point(positions);
g = esri.geometry.geographicToWebMercator(g);
x = g.x;
y = g.y;
回答by YinchaoOnline
You should try geographicToWebMercatormethod in esri/geometry/webMercatorUtilsmodule.see the detailed documentation.
您应该尝试模块中的geographicToWebMercator方法esri/geometry/webMercatorUtils。请参阅详细文档。
//a point in GCS_WGS_1984(wkid is 4326)
var point = new Point(-118.15, 33.80, new SpatialReference({
wkid: 4326
}));
var pointWebMercator = webMercatorUtils.geographicToWebMercator(point);
alert("the point in 102100 is ( " + pointWebMercator.x + "," + pointWebMercator.y + " )");
a live demo:
现场演示：
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta name="viewport" content="initial-scale=1, maximum-scale=1,user-scalable=no" />
<title>Converting geographic WGS 84 to Web Mercator 102100</title>
<link rel="stylesheet" href="https://js.arcgis.com/3.20/esri/css/esri.css">
<style>
html,
body,
#map {
height: 100%;
margin: 0;
padding: 0;
}
</style>
<script src="https://js.arcgis.com/3.20/"></script>
<script>
var map;
require(["esri/map", "esri/geometry/Point", "esri/SpatialReference", "esri/geometry/webMercatorUtils", "dojo/domReady!"], function (Map, Point, SpatialReference, webMercatorUtils) {
map = new Map("map", {
basemap: "topo", //For full list of pre-defined basemaps, navigate to http://arcg.is/1JVo6Wd
center: [-122.45, 37.75], // longitude, latitude
zoom: 13
});
//a point in GCS_WGS_1984(wkid is 4326)
var point = new Point(-118.15, 33.80, new SpatialReference({
wkid: 4326
}));
var pointWebMercator = webMercatorUtils.geographicToWebMercator(point);
alert("the point in 102100 is ( " + pointWebMercator.x + "," + pointWebMercator.y + " )");
});
</script>
</head>
<body>
<div id="map"></div>
</body>
</html>Hope it could help you.
希望能帮到你。
回答by Bjorn Svensson
You don't actually have to convert the latitide/longitude to add points to a basemap that's in webmercator.
您实际上不必转换纬度/经度以将点添加到 webmercator 中的底图。
You can create the Point directly using latitude/longitude (and the API will internally do the conversion from geographic to webmercator) in a few different ways. This is available since version 3.3 (January 2013).
您可以通过几种不同的方式直接使用纬度/经度创建点（API 将在内部进行从地理到 webmercator 的转换）。自 3.3 版（2013 年 1 月）起可用。
var point = new Point(-98, 38); // note that longitude(x) comes before the latitude(y).
// or as an array
var point = new Point([-98, 38]);
// or as an object
var point = new Point({latitude: 38, longitude: -98});
https://developers.arcgis.com/javascript/3/jsapi/point-amd.html#point4
https://developers.arcgis.com/javascript/3/jsapi/point-amd.html#point4
