[mapserver-users] UNION raster layers returns blank image

[Travis Kirstine]

Hi All,

I have been having some issues using the UNION option in the mapfile.
I'm trying to set up a WMS server with several "source" raster layers
and provide them all as a single union layer to the client.   I don't
want the source layers visible in the GetCapabilities, only the union
layer so I have been using a combination of the own_enable_request and
CONNECTIONTYPE UNION.  It seems to work in the GetCapabilites, only
the union layer appears however only blank images are returned from
the GetMap requests.  The layers portion of my mapfile is below, I
have set the "ows_enable_request" "*" in the WEB METADATA.  Any help
would be much appreciated


    # York Region 2009 - Union
    LAYER
        NAME "0937york_union"
        TYPE RASTER
        CONNECTIONTYPE UNION
        CONNECTION
"0937york_1km_mstif,0937york_5km_mstif,0937york_10km_mstif,0937york_overall_mstif"
        METADATA
            "wms_title" "York Region UNION"
            "wms_extent" "594999 4842001 649999 4918001"
        END
        CLASS
        END
        PROJECTION
            "init=epsg:26917"
        END
    END
    # York Region 2009 - 15cm
    LAYER
        NAME "0937york_1km_mstif"
        TYPE RASTER
        TILEINDEX /var/local/data/0937YORK_1km_mstif/york_1km_mstindex
        TILEITEM location
        MAXSCALEDENOM 7500
        OFFSITE 0 0 0
        METADATA
            "ows_enable_request" "* !GetCapabilities"
        END
        PROJECTION
            "init=epsg:26917"
        END
    END
    LAYER
        NAME "0937york_5km_mstif"
        TYPE RASTER
        TILEINDEX /var/local/data/0937YORK_5km_mstif/york_5km_mstindex
        TILEITEM location
        MINSCALEDENOM 7500
        MAXSCALEDENOM 40000
        OFFSITE 0 0 0
        METADATA
            "ows_enable_request" "* !GetCapabilities"
        END
        PROJECTION
            "init=epsg:26917"
        END
    END
    LAYER
        NAME "0937york_10km_mstif"
        TYPE RASTER
        TILEINDEX /var/local/data/0937YORK_10km_mstif/york_10km_mstindex
        TILEITEM location
        MINSCALEDENOM 40000
        MAXSCALEDENOM 400000
        OFFSITE 0 0 0
        METADATA
            "ows_enable_request" "* !GetCapabilities"
        END
        PROJECTION
            "init=epsg:26917"
        END
    END
    LAYER
        NAME "0937york_overall_mstif"
        TYPE RASTER
        DATA /var/local/data/0937YORK_overall_mstif/0937YORK_100m_overall.tif
        MINSCALEDENOM 400000
        OFFSITE 0 0 0
        METADATA
            "ows_enable_request" "* !GetCapabilities"
        END
        PROJECTION
            "init=epsg:26917"
        END
    END


Regards