[Users] Problem showing WMS in Mercator projection

Tue Feb 15 13:58:28 CET 2011

Hi Erwin,

my source code looks like this:

                var proj4326 = new OpenLayers.Projection("EPSG:4326");

                var projmerc = new OpenLayers.Projection("EPSG:900913");

map = new OpenLayers.Map({

        projection: projmerc,

        displayProjection: proj4326,

        units: "m",

        numZoomLevels: 19,

        maxResolution: 156543.0339,

        maxExtent: new OpenLayers.Bounds(-20037508, -20037508,

                                         20037508, 20037508.34),

         controls: []

});

                var lonlatEurope = new OpenLayers.LonLat(12.0849609375, 47.79839667295524);

                lonlatEurope.transform(proj4326, projmerc);

                var osm = new OpenLayers.Layer.OSM.Mapnik("OSM Mapnik", {

                                               transparent: true

                               },{

                                               visibility: true

                               }

                )

                layers.push(osm);

                //Layer is in WGS 84 projection

layers.push(new OpenLayers.Layer.WMS("ThermoMap Countries", geoserverURL, {

            layers: "ThermoMap:ThermoMap_Partners_Countries",

            transparent: true,

            format: 'image/png'

        }, {

            singleTile: true,

            isBaseLayer: false,

            visibility: false

        }

));

                map.addLayers(layers);

                map.setCenter(lonlatEurope, 4, true, true);

Best regards

Lucia

Dipl.-Geogr. Lucia Morper-Busch | Researcher

University of Salzburg | Centre for Geoinformatics - Z_GIS

Schillerstr.30 | Techno-Z, Block 15, 3rd floor | 5020 Salzburg, Austria

Phone +43 (0)662 8044 5298 | Fax +43 (0)662 8044 5260

> Z_GIS…experts for the spatial view <http://www.zgis.at/research> 

Von: users-bounces at geoext.org [mailto:users-bounces at geoext.org] Im Auftrag von Erwin Sevens
Gesendet: Dienstag, 15. Februar 2011 10:59
An: users at geoext.org
Betreff: [Users] Problem showing WMS in Mercator projection

Hi,

I am trying to combine WMS-layers with the Openstreet Map as background.
The WMS-layers disapear as soon as I zoom in.
When working in geographic projection, I manage to get the WMS to show on a background layer.
I know it is possible as in the opengeo suite, it is possible to do it. Unfortunately, I cannot see how they did it.
I have added  two simple examples with layers available on the net and the javascripts refering  to the online sources.

Can somebody explain me what I do wrong?

A working simple example with the default projection:
====================================
<html>
<head>

<title> A working GeoExt Map </title>
<script src="http://extjs.cachefly.net/ext-3.2.1/adapter/ext/ext-base.js" type="text/javascript"></script>
<script src="http://extjs.cachefly.net/ext-3.2.1/ext-all.js"  type="text/javascript"></script>
<link rel="stylesheet" type="text/css" href="http://extjs.cachefly.net/ext-3.2.1/resources/css/ext-all.css"></link>
<script src="http://openlayers.org/api/OpenLayers.js" type="text/javascript"></script>
<script src="http://api.geoext.org/1.0/script/GeoExt.js" type="text/javascript"></script>
<link rel="stylesheet" type="text/css" href="http://api.geoext.org/1.0/resources/css/geoext-all-debug.css"></link>

<script type="text/javascript">
    Ext.onReady(function() {

        var map = new OpenLayers.Map({allOverlays: true});
        var kansas = new OpenLayers.LonLat(-99, 39);

        var usa = new OpenLayers.Layer.WMS(
            "usa", "http://demo.opengeo.org/geoserver/wms",
            {
                height: '330',
                width: '680',
                layers: 'nurc:Img_Sample',
                styles: '',
                srs: 'EPSG:4326',
                format: 'image/png'
            },
            {singleTile: true, ratio: 1} 
        );        
        var layer = new OpenLayers.Layer.WMS(
            "USA pop",
            "http://demo.opengeo.org/geoserver/wms",
            {layers: "topp:states"},
            {opacity: 0.5}
        );  

        map.addLayer(usa);
        map.addLayer(layer);

        new GeoExt.MapPanel({
            renderTo: 'gxmap',
            height: 400,
            width: 600,
            map: map,
            center: kansas,
            zoom: 4,
            title: 'A working GeoExt Map, default projection'
        });
    });
</script>
</head>
<body>
<div id="gxmap"></div>
</body>
</html>

============================================
the not working example with mercator projection
============================================

<html>
<head>

<title> A WMS failing GeoExt Map </title>
<script src="http://extjs.cachefly.net/ext-3.2.1/adapter/ext/ext-base.js" type="text/javascript"></script>
<script src="http://extjs.cachefly.net/ext-3.2.1/ext-all.js"  type="text/javascript"></script>
<link rel="stylesheet" type="text/css" href="http://extjs.cachefly.net/ext-3.2.1/resources/css/ext-all.css"></link>
<script src="http://openlayers.org/api/OpenLayers.js" type="text/javascript"></script>
<script src="http://api.geoext.org/1.0/script/GeoExt.js" type="text/javascript"></script>
<link rel="stylesheet" type="text/css" href="http://api.geoext.org/1.0/resources/css/geoext-all-debug.css"></link>

<script type="text/javascript">
    Ext.onReady(function() {

        var geographic = new OpenLayers.Projection("EPSG:4326");
        var mercator = new OpenLayers.Projection("EPSG:900913");

        var map = new OpenLayers.Map({allOverlays: true,
                    projection: "EPSG:900913",
                    units: "m"
        });
        var kansas = new OpenLayers.LonLat(-99, 39).transform(geographic, mercator);

        var osm = new OpenLayers.Layer.OSM();                        
        var layer = new OpenLayers.Layer.WMS(
            "USA pop",
            "http://demo.opengeo.org/geoserver/wms",
            {layers: "topp:states"},
            {opacity: 0.5}
        );  

        map.addLayer(osm);
        map.addLayer(layer);

        new GeoExt.MapPanel({
            renderTo: 'gxmap',
            height: 400,
            width: 600,
            map: map,
            center: kansas,
            zoom: 4,
            title: 'A WMS failing GeoExt Map, Mercator projection'
        });
    });
</script>
</head>
<body>
<div id="gxmap"></div>
</body>
</html>

Erwin Sevens | OVAM
http://www.ovam.be

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