OpenLayers 投影
我可以成功地做到：
point.transform(new OpenLayers.Projection("EPSG:900913"), new OpenLayers.Projection("EPSG:4326"));
到谷歌格式（以米为单位）的点，但是当我想做相反的事情：
point.transform(new OpenLayers.Projection("EPSG:4326"), new OpenLayers.Projection("EPSG:900913"));
到4326（常规纬度/经度格式）的点时，我遇到了一些问题。
当我进行转换时，任何负值似乎都会变成 NaN （不是数字）。关于反向转换有什么我不明白的地方吗？
编辑：更糟糕的是，当我没有负值时，坐标似乎偏离了。我通过在屏幕上绘制一个正方形来获取坐标，然后将这些坐标保存到数据库中并稍后加载它们。我可以在非洲顶端（正坐标）附近画一个正方形，然后当它加载时，它就在大西洋的非洲顶端附近。我肯定做错了什么......
编辑：这是我的代码：http://pastie.org/911524
具体来说：这就是我初始化地图的方式：
var navControl = new OpenLayers.Control.Navigation();
map = new OpenLayers.Map('map', {
// restrictedExtent: bounds.clone(),
});
//actually draws the map
layerMapnik = new OpenLayers.Layer.OSM.Mapnik("Mapnik", {
displayOutsideMaxExtent: false,
wrapDateLine: true
//numZoomLevels: 10
});
I can succesfully do:
point.transform(new OpenLayers.Projection("EPSG:900913"), new OpenLayers.Projection("EPSG:4326"));
To a point that is in the google format (in meters), but when I want to do the reverse:
point.transform(new OpenLayers.Projection("EPSG:4326"), new OpenLayers.Projection("EPSG:900913"));
to a point that is in 4326 (regular lat/lon format), I am having some issues.
Any negative value seems to become NaN (not a number) when I do the transformation. Is there something about the transformation in reverse that I don't understand?
Edit: Even worse, when I have no negative values, the coordinates seem off. I am getting the coordinates by drawing a square on the screen, then saving those coordinates to a database and loading them later. I can draw a square near the tip of africa (positive coordinates), and then when it loads it's near the top of africa, in the atlantic ocean. I'm definitely doing something wrong....
Edit: Here's my code: http://pastie.org/911524
Specifically: this is how I initialize my map:
var navControl = new OpenLayers.Control.Navigation();
map = new OpenLayers.Map('map', {
// restrictedExtent: bounds.clone(),
});
//actually draws the map
layerMapnik = new OpenLayers.Layer.OSM.Mapnik("Mapnik", {
displayOutsideMaxExtent: false,
wrapDateLine: true
//numZoomLevels: 10
});
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评论（2）
啊，我想通了：
在我的代码中，有一次我混淆了纬度和经度，这把一切都搞乱了。
Ah, I figured it out:
At one point in my code I confused latitude and longitude it was messing everything up.
如果您确实想使用所有坐标转换功能，则应该使用 proj4js 增强 openlayers http://proj4js.org/ 完整的坐标转换框架。
If you really want to use all the coordinate transformation power, you should enhance openlayers with proj4js http://proj4js.org/ a full coordinate transformation framework.