[OpenLayers-Users] WMS layer not bounded by extents

[David Quinn]

Hi List,

I'm using openlayers to send a WMS query based on a user-chosen extent of a
rectangular polygon. My javascript is as follows:

    // request raster layer
    rasterLayer = new OpenLayers.Layer.WMS(
           "Road layer..... ",
           "http://mysite/mapserv.cgi?map=roads.map&",
           {    layers: 'roads',
                transparent: true
                },
           {    maxExtent: centralBounds, // extents of rectangular polygon
drawn on-screen
                displayOutsideMaxExtent: false, // this is false by
default, but I tried adding it anyway
                tileSize:new OpenLayers.Size(80,80), // by default this is
256
                opacity: 0.5,
                gutter: 0}
       );

I am trying to return information from a raster using Mapserver.The query
returns a WMS layer, but only three of the four sides of the polygon have
the correct extents, and the WMS layer is a square. I've tried to
illustrated this in the below diagram:

X = requested
_____________
|                       |
|       XXXX       |
|       XXXX       |
|                       |
---------------------

Y = returned
_____________
|       YYYY        |
|       YYYY        |
|       YYYY        |
|                        |
----------------------

The extents are definitely correct, as I've used them for querying non-WMS
data that is displayed in-browser. When I make the tileSize smaller (e.g.
tileSize:new OpenLayers.Size(10,10), it fills the box perfectly. Initially,
I noticed that I was getting the following error message in Firebug:
"NetworkError: 404 Not Found - http://mysite.com/js_libraries/img/blank.gif".
My openlayers javascript is stored in the 'js_libraries' folder. I added a
folder 'img' with 'blank.gif', and my problem temporarily disappeared,
before the next page reload.

I asked a very similar question on the Mapserver list yesterday, thinking
it was a mapserver problem. I thought I had resolved it, but I have not,
and I don't think it is related to Mapserver. I'd appreciate any
suggestions - I'd prefer not to reduce tilesizes as it makes the raster
very slow to load.

Thanks,
David
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