[OpenLayers-Users] Blank WMS tiles displaying over Bing hybrid layer

[Marc Jansen]

Hi Chris,

just some notes:

On 12.06.2010 19:04, Chris Lam wrote:
> Hello,
>
>    

[shortened]

> Here is my mapserver request URL from one tile:
>
> http://localhost/cgi-bin/mapserv.exe?MAP=C%3A%2Fms4w%2Fapps%2FLB_MAPFILES%2FPARCELS_MAPFILE.map&LAYERS=PARCELS_URL_pol&TRANSPARENT=true&DISPLAYPROJECTION=EPSG%3A4326&ISBASELAYER=false&SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&STYLES=&EXCEPTIONS=application%2Fvnd.ogc.se_inimage&FORMAT=image%2Fpng&SRS=EPSG%3A900913&BBOX=-13719529.331192,6352222.7966734,-13718306.33874,6353445.7891258&WIDTH=256&HEIGHT=256
>
>    

Please try to enable DEBUG for your mapserver: 
http://mapserver.org/mapfile/map.html (DEBUG). Be sure to read the log 
and -- furthermore -- set the URL-Param EXCEPTIONS to 
"application/vnd.ogc.se_inxml".

> Here is my relevant code:
>
> function init () {
> //Configure map
>       var options = {
>            projection: new OpenLayers.Projection("EPSG:900913"),
>            units: "m",
>            maxResolution: 156543.0339
>            maxExtent: new OpenLayers.Bounds(-20037508.34, -20037508.34,
> 20037508.34, 20037508.34)};
> //Create new map object
>       var map = new OpenLayers.Map('map',options);
> //Add a layerswitcher
>       map.addControl(new OpenLayers.Control.LayerSwitcher());
> //Add the Bing map base layer
>       var vemap = new OpenLayers.Layer.VirtualEarth("Virtual Earth",
>          { type: VEMapStyle.Hybrid,
>             sphericalMercator: true,
>             numZoomLevels: 21,
>             maxExtent: new
> OpenLayers.Bounds(-20037508.34,-20037508.34,20037508.34,20037508.34)
>           });
> //Add the WMS parcels overlay layer
>       var parcels_wms = new OpenLayers.Layer.WMS(
>                      "Lions Bay Parcels",
>                      "http://localhost/cgi-bin/mapserv.exe?",
>                      {
>                       map: 'C:/ms4w/apps/LB_MAPFILES/PARCELS_MAPFILE.map',
>                       layers: 'PARCELS_URL_pol',
>                       transparent: 'true',
>                       displayProjection: new
> OpenLayers.Projection("EPSG:4326"),
>                       isBaseLayer: false,
>                       maxExtent: new
> OpenLayers.Bounds(-20037508.34,-20037508.34,20037508.34,20037508.34)},
>                      {
>                        visibility:false
>                      }
>                   );
>    

Do not include the key-value-pairs

transparent: 'true',
                      displayProjection: new
OpenLayers.Projection("EPSG:4326"),
                      isBaseLayer: false,
                      maxExtent: new
OpenLayers.Bounds(-20037508.34,-20037508.34,20037508.34,20037508.34)



within the third parameter of OpenLayers.Layer.WMS. They end up in the 
URL to the maposerver in question and are very likely ignored.

I would guess that indeed you are experiencing a mapserver problem. Try 
to ask over on their list about how to get mapserver to the point that 
it serves maps in 900913.

Hope that helps,
Marc

> //Add the layers to the map object
> map.addLayers([vemap,parcels_wms]);
> //Center the map over the study area
> map.setCenter(new OpenLayers.LonLat(-13718569,6353226), 14);
>
> ...the rest of the code is other map controls, layer opacity adjuster, and
> single-click mouse event handler containing a getfeatureinfo request.
>
> This code seems to be fine, but am I doing something wrong with setting max
> extent or max resolution?  The Bing map itself centers and zooms the way I
> want, but the WMS data is failing to align with it.  Perhaps it could be
> displayed outside of the extents and therefore not rendered at all?  Or is
> this a mapserver problem where my server is not requesting tiles in
> epsg:900913 to align with Bing tiles?  In another web template where I have
> not implemented the links to Bing maps, my wms layer displays fine since the
> map projection is 4326 and not 900913.  That template has a line of code
> map.zoomToMaxExtent(); that, when commented out, makes the working overlay
> disappear completely.  Don't know if that is a helpful clue.
>
> I have tried starting from a basic html template to add code line by line to
> isolate the problem.  It works fine until I add the Bing layer which just
> wipes out the previously displayed WMS parcel layer to just display the Bing
> hybrid with the overlay present, but rendered completely as blank 256x256
> tiles.
>
> Thank you for any advice, for I am out of leads!
>
> Regards,
>
> Chris Lam
>
> P.S. If this is a duplicate posting, you have my sincere apologies for the
> lapse in etiquette.  At the time of this message, I was not subscribed to
> the mailing list and I think you have to be for messages to be accepted.
> Also I did not see my message in the users archive or on the Nabble forum
> where I found this list.  Thank you for your understanding.
>    


-- 

   .................................................................
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   Dipl.-Geogr. Marc Jansen
   - Anwendungsentwickler -

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