[mapserver-users] WMS - getCapabilities BBOX

[Frank Warmerdam]

Guillaume Sueur wrote:
> Hi,
> 
> I've got a problem with mapserver's WMS getCapabilities. My data are 
> projected in a local projection (EPSG:27563). Apparemtly, the 
> getCapabilities calculates a LatLongBoundigBox, given in WGS84. But 
> these values are wrong, with a serious shift on the west.
> When I translate the data with ogr2ogr to EPSG:4326 in KML, tha data is 
> at the correct place in GoogleEarth.

Guillaume,

EPSG:27563 has a prime meridian other than greenwich. I presume that is
causing the problem.  In fact, looking through the code I think the latlong
box is actually computed in the GCS of the coordinate system in question,
rather than WGS84.  So in your case there is a serious error in the east
west axis, but in other situations people may see small errors due to the
lack of datum adjustment.

I would suggest you file a ticket on it.  Specifically the ticket might
note that msOWSPrintLatLonBoundingBox() just passes NULL for the destination
coordinate system, and msProjectPoint() just treats this as a special case
to use the lat/long coordinate system (GCS) associated with the projected
coordinate system.  So in this case we see a big error because you are getting
values relative to the paris prime meridian.

This is likely to affect a number of places in MapServer (WMS, and WCS
at least).  Please add me ("warmerdam") as a cc on the created ticket.
I might not fix it, but I should at least be able to help.

Best regards,
-- 
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | President OSGeo, http://osgeo.org