[mapserver-users] Projection Extent and Zoom issues - Openlayers

Wed Aug 12 00:52:36 PDT 2009

Hi,

I have had this problem for a couple of weeks now and I still cant get past it. Basically when I view my map of the UK via openlayers it is zoomed in very close. I want to zoom out but whatever I try doesn’t work – usually results in just the background colour of my map being displayed.

I believe it might be my EXTENT which is incorrect as I am using epsg:4326 (a spherical coordinate system). My map file is a Mapserver Export from Quantim GIS and gave me the EXTENT -888385.321101 -31000.000000 1548385.321101 1271000.000000. How can I convert this into a Geographic extent to match with my projection (epsg:4326)?

My map and javascript file is below.

Any help greatly appreciated

Thanks

MAP

    NAME UK1
            PROJECTION
               "init=epsg:4326"
            END    
    SIZE 1600 1200
    IMAGECOLOR  153 204 255
    IMAGETYPE JPEG
    SHAPEPATH "http://localhost/openlayers/data/"
    EXTENT  -888385.321101 -31000.000000 1548385.321101 1271000.000000       UNITS DD

            WEB
              TEMPLATE "http://localhost/openlayers/examples/test.html"
              LOG "\ms4w\tmp\ms_tmp\log.txt"
      IMAGEPATH "\ms4w\tmp\ms_tmp\"
      IMAGEURL "/ms_tmp/"
      METADATA
                        'wms_title' "map"
        'wms_onlineresource'  "http://127.0.0.1./cgi-bin/mapserv?map=uk1.map"
      END

            END

  LAYER

               NAME "UK"
               METADATA
                 'wms_title' "wms_demo"
               END
               STATUS DEFAULT
               TYPE raster
               TILEINDEX "map"
               TILEITEM "Location"
               PROJECTION
                 "init=epsg:4326"
               END
               CLASS
                 STYLE
                  COLOR 0 0 0
                 END
                 LABEL
                  COLOR 0 0 0
                  SIZE SMALL
                 END

               END

  END

END

Openlayers File:

<html xmlns="http://www.w3.org/1999/xhtml">
  <head>MAPPING TEST
    <style type="text/css">
        #map {
            width: 90%;
            height: 90%;
            border: 8px solid black;
        }
    </style>
    <script src="../lib/OpenLayers.js"></script>
    <script type="text/javascript">

      var zoom = 100;
      var bounds = new OpenLayers.Bounds(-888385.321101, -31000.000000, 1548385.321101, 1271000.000000);
      var map, layer;

      function init(){
      map = new OpenLayers.Map('map', { maxExtent: bounds, numZoomlevels: 10 });
      map.addControl(new OpenLayers.Control.PanZoomBar());
      map.addControl(new OpenLayers.Control.OverviewMap());
      map.addControl(new OpenLayers.Control.MousePosition());
      layer = new OpenLayers.Layer.WMS( "OpenLayers WMS", 
      "http://127.0.0.1/cgi-bin/mapserv.exe?", { layers: 'uk', map: '/ms4w/apps/openlayers-2.5/data/uk1.map' },
      { gutter: 15 });      
      map.addLayer(layer);
      map.zoomToExtent(bounds);
      map.setCenter(new OpenLayers.zoom);   

      }

    </script>
  </head>
  <body onload="init()">
    <div id="map"></div>
  </body>
</html>
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