use native boundingbox instead of reprojecting latlonboundingbox

[bartvde@…]

Hi list,

today we ran into a strange problem with Mapserver WMS client, when zooming into
a Demis WMS layer, Mapserver WMS client did not want to render a layer, it did
not even try to request the layer. Our application operates in EPSG:28992
(Netherlands). 

This is the important part of the WMS capabilities:

<LatLonBoundingBox minx="-180" miny="-90" maxx="180" maxy="90"/>
<BoundingBox SRS="EPSG:28992" minx="48443.3472125024" miny="404023.309341862"
maxx="144763.347212502" maxy="484658.309341862"/>

After a little digging in the code, I found something strange in mapwmslayer.c:

// Reproject latlonboundingbox to the selected SRS for the layer and
// check if it overlaps the bbox that we calculated for the request
msProjectRect(&(map->latlon), &(lp->projection), &ext);

So what it is gonna do, is reproject -180,-90,180,90 into the Dutch RD system,
which is not valid outside of Netherlands :)

This is strange since it could easily use the other BoundingBox specified in the
WMS capabilities. It should only try to reproject if a WMS service would not
provide that one in my opinion.

But ofcourse one can argue that the Demis WMS service did not provide
correct/precise values for the LatLonBoundingBox.

This is the MAP file definition used (I needed to comment the
wms_latlonboundingbox to get it to work, but ofcourse when dynamically added
this metadata gets written all the time):

  LAYER
    CONNECTION "http://myserver/wms/wms.asp?wms=TOPOFOTO&"
    CONNECTIONTYPE WMS
    DEBUG ON
    DUMP TRUE
      METADATA
        "wms_srs"	"EPSG:28992"
        #"wms_latlonboundingbox"	"-180 -90 180 90"
        "wms_name"	"Luchtfoto"
        "wms_formatlist"	"image/png,image/jpeg,image/gif,image/bmp,image/swf"
        "wms_format"	"image/png"
        "wms_boundingbox"	"EPSG:28992 48443.34766 404023.3125 144763.34375
484658.3125"
        "wms_server_version"	"1.1.1"
        "wms_title"	"Luchtfoto"
      END
    NAME "demis-Luchtfoto"
    PROJECTION
      "init=epsg:28992"
    END
    SIZEUNITS PIXELS
    STATUS ON
    TEMPLATE "blank.html"
    TOLERANCE 0
    TOLERANCEUNITS PIXELS
    TYPE RASTER
    UNITS METERS
  END

[bartvde@…]

What I wondered when trying to create a patch for this is, how does the
Mapserver hashtable structure deal with duplicate/multiple keys? Eg this would
be valid:

"wms_boundingbox" "EPSG:28992 48443.34766 404023.3125 144763.34375 484658.3125"
"wms_boundingbox" "EPSG:4307 XMIN YMIN XMAX YMAX"

Won't this be causing problems?

[bartvde@…]

Setting target to FUTURE.