[OpenLayers-Users] Spherical Mercator and 4326 alignment problem

[Arlen Poort]

I'm not a wizard myself, but I had the same problem a few months ago. In my
Openlayers code, I finally put in the code below, and this gave a good
result. But perhaps this is of no help.
In my Mapfile, I don't have the Google projection (900913), but WGS84
(4326).


Best regards,

Arlen

        function init(){
            var mapoptions = {
                projection: new OpenLayers.Projection("EPSG:900913"),
                displayProjection: new OpenLayers.Projection("EPSG:4326"),
                units: "m",
                maxExtent: new
OpenLayers.Bounds(375000,6550000,800000,7100000),
                tileSize: new OpenLayers.Size(256,256)
            };
(...etc...)




On Tue, Aug 17, 2010 at 12:04 AM, B. Heath Robinson <bheathr at gmail.com>wrote:

> I am having a problem with a WMS layer lining up on top of a Google map.
>  It appears to be about 15mi south of were it needs to be.  I am assuming
> this is because of the fact that spherical mercator ignores the fact the
> earth is an ellipse.  Anyway, I have included my openlayers code and my
> mapfile as after spending hours search seems to be helpful.
>
> I get the same results using either a shapfile or postgis data each with a
> different projection.
>
> I am using what I believe to be the best method.  If I use "reproject:true"
> the map does line up, but that causes other known problems and is
> deprecated.  Any help would be greatly appreciated.
>
> --------MAPFILE----------
> MAP
>  NAME "Test Map"
>  SIZE 256 256
>  MAXSIZE 40096
>  UNITS feet
>  DEBUG ON
>  DEBUG 5
>  CONFIG "PROJ_LIB" "/usr/local/share/proj"
>  CONFIG "MS_ERRORFILE" "/tmp/mapserver.log"
>  EXTENT -10899765.713460 3586328.494261 -10787636.706166 3654203.662907
>
>  PROJECTION
>     "init=epsg:900913"
>  END
>
>  IMAGECOLOR 255 255 255
>  IMAGEQUALITY 85
>  IMAGETYPE AGGA
>
>  OUTPUTFORMAT
>    NAME AGGA
>    DRIVER 'AGG/PNG'
>    MIMETYPE 'image/png'
>    IMAGEMODE RGBA
>    EXTENSION 'png'
>    #FORMATOPTION "QUANTIZE_FORCE=on"
>    #FORMATOPTION "QUANTIZE_COLORS=256"
>    FORMATOPTION "QUANTIZE_NEW=on"
>  END
>
>  LAYER
>    NAME 'cities'
>    TYPE POLYGON
>    DUMP true
>    PROCESSING "CLOSE_CONNECTION=DEFER"
>    CONNECTIONTYPE postgis
>    CONNECTION "dbname='regnumvisum' host=localhost port=5432 user='ecweb'
> password='tklM3E1m0' sslmode=disable"
>    DATA 'limits FROM "maps_city" USING UNIQUE id USING srid=4326'
>    METADATA
>      'ows_title' 'parcels'
>      'wms_srs' 'EPSG:900913 EPSG:3785'
>      'wms_format' 'image/png'
>    END
>    STATUS ON
>    TRANSPARENCY 50
>    PROJECTION
>      "init=epsg:4326"
>    END
>    CLASSITEM 'id'
>      CLASS
>       NAME 'default'
>       STYLE
>         SYMBOL 0
>         SIZE 7.0
>         OUTLINECOLOR 255 255 255
>         COLOR [color]
>         ANTIALIAS TRUE
>       END
>    END
>  END
>
>  LAYER
>    NAME 'cities-shp'
>    TYPE POLYGON
>    DUMP true
>    DATA /Users/bheathr/EdenicConfluence/sample_files/Unified
>    METADATA
>      'ows_title' 'parcels'
>      'wms_srs' 'EPSG:900913 EPSG:3785'
>      'wms_format' 'image/png'
>    END
>    STATUS ON
>    TRANSPARENCY 50
>    PROJECTION
>      "init=epsg:2277"
>    END
>    CLASSITEM 'OBJECTID'
>      CLASS
>       NAME 'default'
>       STYLE
>         SYMBOL 0
>         SIZE 7.0
>         OUTLINECOLOR 255 255 255
>         COLOR 0 0 0
>         ANTIALIAS TRUE
>       END
>    END
>  END
> END
> ---------MAPFILE-------------
> ---------Open Layers---------
> function init(){
>            var options = {
>                projection: "EPSG:900913",
>                units: "ft",
>                maxResolution: 156543.0339,
>                maxExtent: new OpenLayers.Bounds(-20037508, -20037508,
>                                                 20037508, 20037508)
>            };
>            map = new OpenLayers.Map('map', options);
>
>            var gmap = new OpenLayers.Layer.Google(
>                "Google Streets",
>                {'sphericalMercator': true}
>            );
>
>            cities = new OpenLayers.Layer.WMS("Bell Cities",
>                                            "
> http://localhost/cgi-bin/mapserv",
>                                            {'map':
> '/Users/bheathr/EdenicConfluence/regnumvisum/etc/test.map',
>        'layers': 'cities-shp',
>                                             'format':'png'},
>                                            {'reproject': false,
>                                             'opacity': 0.4,
>                                             'isBaseLayer': false,
>                                             'wrapDateLine': true});
>
>            // create a vector layer for drawing
>            vector = new OpenLayers.Layer.Vector("Editable Vectors");
>
>            map.addLayers([gmap, cities]);
>            map.addControl(new OpenLayers.Control.LayerSwitcher());
>   centerMap(-97.67112,30.974599,-97.18326,31.18982);
>        }
>
>     function centerMap(top,left,bottom,right) {
>          var proj = new OpenLayers.Projection("EPSG:4326");
>          var bounds = new OpenLayers.Bounds(top,left,bottom,right);
>          bounds.transform(proj, map.getProjectionObject());
>          if (!map.getCenter()) map.zoomToExtent(bounds);
>      }
>
> ---------Open Layers---------
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>
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