为OpenLayers转换GPS坐标 [英] Transforming GPS coordinates for OpenLayers

问题描述

我的坐标为48.3185005,14.2853003（由奥地利林茨协调）我从navigator.geolocation.getCurrentPosition（）或Google地图地理编码API获得。
现在我想在地图上显示这一点。

地图显示正确的位置需要进行哪些转换，以及如何执行这些转换的OpenLayers？
目前，我总是在非洲以东的某个地方。 这是因为OpenStreetMap数据是一个投影坐标系统，称为Web墨卡托投影仪，即以米为单位，而您的GPS数据为纬度/经度。这就是为什么所有点都出现在非洲西海岸的海洋中，就像在以米为单位覆盖整个地球的坐标系中一样，180,180和-90,90范围内的任何坐标似乎都在这个小区域内加纳海岸。我注意到你在非洲东部的原帖中，但在评论中，你说大西洋，我认为你的意思是西部，这与我的解释一致。这是正确的吗？

通过指定不同的地图投影和显示投影，您可以在地图构造函数中处理这个问题：请参阅 http://docs.openlayers.org/library/spherical_mercator.html

你需要一些东西：

  var map = new OpenLayers.Map（map，{
 projection ：新的OpenLayers.Projection（EPSG：900913），
 displayProjection：新的OpenLayers.Projection（EPSG：4326）
}）; 
  

EPSG：3857（最初为900913）是Spherical Mercator的正式名称，并在此与4326经纬度）内置于OpenLayers中。

I am building a project in JavaScript that uses OpenLayers with an OpenStreetMap layer.

I have the coordinates "48.3185005, 14.2853003" (the coordinated of Linz, Austria) which I get from either navigator.geolocation.getCurrentPosition() or the Google Maps Geocoding API. Now I want to show this point on the map.

Which transformations are necessary for the map to display the correct location and how do I do these transformations with OpenLayers? At the moment, I am always getting some point east of Africa.

解决方案

This is because OpenStreetMap data is a projected coordinate system, known as Web Mercator, ie, it is in meters, whereas your GPS data are in lat/lon. This is why all points appear to be in the sea off the West coast of Africa, as in a coordinate system covering the whole globe in meters, any coordinates in the range 180,180 and -90,90 will appear to be in that small area off the coast of Ghana. I notice in your original post you said East of Africa, but in a comment, you said Atlantic Ocean, from which I am assuming you meant West, which is consistent with my explanation. Is this correct?

You can deal with this in you map constructor by specifying a different map projection and display projection: see http://docs.openlayers.org/library/spherical_mercator.html

You want something along the lines of:

var map = new OpenLayers.Map("map", {
  projection: new OpenLayers.Projection("EPSG:900913"),
  displayProjection: new OpenLayers.Projection("EPSG:4326")
});

EPSG:3857 (originally 900913) is the official designation for Spherical Mercator and conversion between this and 4326 (lat/lon) is built into OpenLayers.

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