[英]How to reproject layers (using GeoServer and OpenLayers) in order to overlay on the google maps
我正在使用OpenLayers編寫代碼。 在這段代碼中，我想以不同的縮放級別顯示不同的圖層。 直到這里，一切正常。 當我嘗試將Google地圖添加為基本圖層時，我的問題就開始了。 我的圖層的投影系統與Google圖層不一致，因此應重新投影。 我嘗試使用Proj4js.transform方法，但是沒有用。 我的圖層在EPSG：3006（瑞典）中，而Google圖層在EPSG：900913中。 以下代碼導致投影圖層向右移動。 這意味着重新投影無法正常工作。 請讓我知道我的代碼有什么問題。
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<title>OpenLayers map preview</title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<!-- Import OL CSS, auto import does not work with our minified OL.js build -->
<link rel="stylesheet" type="text/css" href="http://gisl.nateko.lu.se:8088/geoserver/openlayers/theme/default/style.css">
<!-- add here more css definition libraries-->
<!-- Basic CSS definitions -->
<style type="text/css">
body {
font-family: Verdana, Geneva, Arial, Helvetica, sans-serif;
font-size: small;
}
/* Toolbar styles */
#toolbar {
position: relative;
padding-bottom: 0.5em;
display: none;
}
/* The map and the location bar */
#map {
clear: both;
position: relative;
width: 337px;
height: 512px;
border: 2px solid black;
}
#wrapper {
width: 337px;
height: 50px;
}
#location {
float: right;
font-family: Arial, Verdana, sans-serif;
font-size: 12px;
color: #483D8B;
background-color: white;
}
#scale {
float:left;
font-family: Arial, Verdana, sans-serif;
font-size: 12px;
color: #483D8B;
background-color: white;
}
#nodelist{
font-family: Arial, Verdana, sans-serif;
font-size: 14px;
color: #000000;
font-style: normal;
background-color: white;
}
</style>
<!-- Import OpenLayers, reduced, wms read only version -->
<script type="text/javascript" src="http://www.openlayers.org/api/OpenLayers.js"></script>
<!-- add here more js libraries -->
<script src="http://maps.google.com/maps/api/js?v=3.2&sensor=false"></script>
<script src ='proj4js/lib/proj4js-combined.js'></script>
<script src ='proj4js/lib/deprecated.js'></script>
<script defer="defer" type="text/javascript">
var map;
var untiled;
var tiled;
var pureCoverage = false;
// pink tile avoidance
OpenLayers.IMAGE_RELOAD_ATTEMPTS = 5;
// make OL compute scale according to WMS spec
OpenLayers.DOTS_PER_INCH = 25.4 / 0.28;
function init(){
format = 'image/png';
var options = {
controls: [],
projection: new OpenLayers.Projection('EPSG:900916'),
displayProjection: new OpenLayers.Projection('EPSG:4326'),
maxExtent: new OpenLayers.Bounds(
-20037508, -20037508,20037508, 20037508.34),
//modify parameter
maxResolution: 5000,
//modify parameter
//setting zoom levels
numZoomLevels:15,
units: 'm',
};
map = new OpenLayers.Map('map', options);
// setup tiled layer
var gphy = new OpenLayers.Layer.Google(
"Google Physical",
{type: google.maps.MapTypeId.TERRAIN, numZoomLevels: 15, sphericalMercator:true}
// used to be {type: G_PHYSICAL_MAP}
);
var gmap = new OpenLayers.Layer.Google(
"Google Streets", // the default
{numZoomLevels: 15, sphericalMercator:true}
// default type, no change needed here
);
var ghyb = new OpenLayers.Layer.Google(
"Google Hybrid",
{type: google.maps.MapTypeId.HYBRID, numZoomLevels: 15, sphericalMercator:true}
// used to be {type: G_HYBRID_MAP, numZoomLevels: 20}
);
var gsat = new OpenLayers.Layer.Google(
"Google Satellite",
{type: google.maps.MapTypeId.SATELLITE,
numZoomLevels: 15,
sphericalMercator:true
}
// used to be {type: G_SATELLITE_MAP, numZoomLevels: 22}
);
//add controls here
map.addControl(new OpenLayers.Control.LayerSwitcher());
map.addControl(new OpenLayers.Control.LayerSwitcher());
map.addControl(new OpenLayers.Control.PanZoomBar());
zf= new OpenLayers.Control.ZoomToMaxExtent({title:"Zoom to max extent"});
// create a panel to locate the zoom extent button & add the panel to the map
// use the code to create the button from ZoomToMaxExtent.js
var panel= new OpenLayers.Control.Panel({defaultControl:zf});
panel.addControls([zf]);
map.addControl(panel);
map.addControl(new OpenLayers.Control.Navigation());
map.addControl(new OpenLayers.Control.Scale($('scale')));
//end add controls
layer2 = new OpenLayers.Layer.WMS(
"Gr2LundKom:districts","http://gisl.nateko.lu.se:8080/geoserver/wms",
{
projection: map.displayProjection,
height: '600',
width: '800',
layers: 'Gr2LundKom:districts',
styles: '',
srs:'EPSG:3006',
format: format,
tiled: 'true',
transparent: 'true',
},
{
buffer: 0,
displayOutsideMaxExtent: true,
isBaseLayer: false,
reproject: true
});
Proj4js.defs["EPSG:3006"] = "+proj=utm +zone=33 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs";
Proj4js.defs["EPSG:4326"] = "+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs";
var src = new OpenLayers.Projection('EPSG:3006');
var dst = new OpenLayers.Projection('EPSG:4326');
Proj4js.transform(src, dst, layer2);
layer2.projection=dst;
layer3 = new OpenLayers.Layer.WMS(
"Gr2LundKom:public_buildings,other_buildings,roads_all,Public_Libraries",
"http://gisl.nateko.lu.se:8080/geoserver/wms",
{
projection: map.displayProjection,
height: '600',
width: '800',
layers: "Gr2LundKom:public_buildings,other_buildings,roads_all,Public_Libraries",
transparent: "true",
styles: '',
srs:'EPSG:3006',
format: format,
tiled: 'true',
transparent: 'true'
},
{
buffer: 0,
displayOutsideMaxExtent: true,
isBaseLayer: false,
reproject: true
});
Proj4js.transform(src, dst, layer3);
layer3.projection=dst;
map.addLayers([gsat,gphy,gmap,ghyb,layer2]);
//map.setCenter(new OpenLayers.LonLat(1335967.698, 6179172.362), 22);
map.zoomToExtent(new OpenLayers.Bounds(
-20037508, -20037508,20037508, 20037508.34));
// change the dislapy layers with the chandge of scale
map.events.register('zoomend', this, function (event) {
var zLevel = map.getZoom();
if( zLevel == 1 || zLevel == 2 || zLevel == 3 )
{
layer3.setVisibility(false);
layer2.setVisibility(true);
}
if( zLevel == 4 || zLevel == 5 || zLevel == 6)
{
layer2.setVisibility(false);
layer3.setVisibility(true);
map.addLayers([gsat,gphy,gmap,ghyb,layer3]);
}
});
}
</script>
</head>
<body onload="init()">
Map viewer using Geoserver and MapLayers
<br><br>
<div id="map">
</div>
<br>
<div id="wrapper">
<div id="location">location</div>
<br>
<div id="scale">
</div>
</div>
<br>
<div id="nodelist" >
--> Click on the map to get feature info
</div>
</body>
好吧，我知道這是一種解決方法，但是我看到您使用的是geoserver，因此您可以將geoserver中的圖層轉換為google mercator（您應該使用代碼EPSG：3857，因為我記得EPSG：900916不適用於我） 。 我也為這個問題而苦惱，這是唯一幫助我的事情。 但是，僅當您使用wms，wfs圖層時，才能輕松轉換此問題。
而且我認為您不應該嘗試在EPSG：4326中可視化所有內容，而應在google mercator中可視化。
我希望這有幫助。
我認為您在這里有錯字，應該是EPSG：900913而不是EPSG：900916，因為它是Google用數字（900913）表示的形式
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