Revision 271fe7aa-89c2-4434-bd4d-d41d2630d87d - Geographic Information Systems Stack Exchange

I am experiencing projection problems with the following set up: 

 - GeoServer with ESPG:4326 based hapefiles (*.shp)
 - OpenJump to edit my shapefiles
 - Openlayers with EPSG:900913 base layers
 - GeoServer provides the shapefiles as WMS to OpenLayers. 

Here is my source code: 

    <html>
    <head>
        <title>Openplanning mit Geoserver</title>
        <meta http-equiv="content-type" content="text/html; charset=ISO-8859-1">
        <script type='text/javascript' src='http://www.openlayers.org/api/OpenLayers.js'></script>
        
    </head>

     <body>
        <div id="map-id"></div>
            <script>
                var geographic = new OpenLayers.Projection("EPSG:4326");
                var mercator = new OpenLayers.Projection("EPSG:900913");
                
                var world = new OpenLayers.Bounds(-180, -89, 180, 89).transform(
                    geographic, mercator
                );
                var vienna_center = new OpenLayers.LonLat(16.3670, 48.205333).transform(
                    geographic, mercator
                );
                
                var options = {
                    projection: mercator,
                    displayProjection: geographic,
                    units: "m",
                    maxExtent: world,
                    maxResolution: 156543.0399
                };
                
                var map = new OpenLayers.Map("map-id",options);
                
                var osm = new OpenLayers.Layer.OSM();

                map.addLayer(osm);

                var vienna = new OpenLayers.Layer.WMS(
                    "Vienna Calling",
                    "http://localhost:8888/geoserver/wms?",
                    {layers: "topp:ma_vienna", 
                    transparent: true}
                );
                map.addLayer(vienna);
                map.setCenter(vienna_center, 8);
                map.addControl(new OpenLayers.Control.LayerSwitcher());
                //zeigt die Koordinaten der aktuellen Mause-Position an
                map.addControl(new OpenLayers.Control.MousePosition());
                
                map.addControl(featureInfo);
                featureInfo.activate();
            </script>
        </div>
     </body>
     </html>

It seems that GeoServer is converting from ESPG:4326 to EPSG:900913 internally. Here you can see a sample request for Vienna: 

    http://localhost:8888/geoserver/wms?LAYERS=topp:ma_vienna&SRS=EPSG:900913&TRANSPARENT=TRUE&SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&STYLES=&FORMAT=image/png&BBOX=1800244.8899219,6116147.6705496,1839380.6483984,6155283.4290261&WIDTH=256&HEIGHT=256

My problem: the requested file looks distored, as you can see here:

![enter image description here][1]

In case I open the WMS layer in the OpenLayers preview of GeoServer, it looks ok: 

![enter image description here][2]

The question is: Why is my shapefile distorted in my OpenLayers application, but not in the GeoServer preview? As you can see, the GeoServer preview uses EPSG:4326 and my OpenLayers application EPSG:900913. But, however, as GeoServer provides a WMS interface with EPSG:900913 capabilities, shouldn't it correctly reproject my vector sources?

Thanks for you replies in advance, Rainer. 


  [1]: https://i.sstatic.net/UcWBQ.png
  [2]: https://i.sstatic.net/P8IMj.png