It's not a bug, just a difference in the extent models between MapServer proper and WMS. The MapServer WMS interface accounts for this difference in the code by adjusting the WMS extent to a MapServer extent. You'd need to make a similar adjustment when doing comparisons. A WMS extent is 1/2 a pixel larger all around (cellsize is the same). The effect is very subtle and most often not even noticeable.
Steve >>> On 12/8/2008 at 3:39 PM, in message <[EMAIL PROTECTED]>, Julien-Samuel Lacroix <[EMAIL PROTECTED]> wrote: > Hi, > > Did you try the other way around? Making the WMS request with a square BBOX? > > Mapserver should return a valid image. Maybe others may help, I remember > a bug of a 1 pixel error in some cases, but I don't remember what it was > exactly. > > Julien > > Roger André wrote: >> Hi Julien, >> >> That makes sense, but it doesn't work. I modified my mapfile so that I >> now generate a 20_deg x 20_deg tile that is 600_pixels x 600_pixels. If >> I georeference that image using the extents, I still get incorrect >> placement. Maybe if I choose an output projection which always has >> square pixels, like spherical mercator (?) this will work. I'll give it >> a shot. >> >> Is there any way to give a WMS request via mapscript and NOT go through CGI? >> >> Roger >> -- >> >> >> >> On Mon, Dec 8, 2008 at 12:25 PM, Julien-Samuel Lacroix >> <[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>> wrote: >> >> Hi, >> >> I guess would be that the WMS use non-square pixels. So if your BBOX >> x/y (rectangle in your case) doesn't match you WIDTH/HEIGHT ratio >> (square in your case) the map will appear stretched. MapServer will >> actually stretch the map to fit the extent in the WIDTH/HEIGHT. >> >> The mode=map don't do that. If your extent doesn't have the same >> ratio, it adds some degree in your extent to fit the size. >> >> Make sure your BBOX and EXTENT are a square in your requests and retry >> >> >> Julien >> >> Roger André wrote: >> >> Hi All, >> >> I think I'm having an instance of cranial flatulation, but maybe >> not. Hopefully you can set me straight. >> >> I need to create an image with Mapserver using mapscript that I >> can then georeference manually and use in another application. >> It needs to look exactly the same as the image I can already >> generate via a WMS call that looks like this: >> >> > http://localhost/cgi-bin/mapserv?map=/var/www/mapfiles/hydro/hydro.map >> &SERVICE=WMS >> &version=%221.1.1%22 >> &REQUEST=GetMap >> &LAYERS=imagery >> &STYLES=&BBOX=-125,39,-108,54 >> &WIDTH=600 >> &HEIGHT=600 >> &FORMAT=png >> &SRS=epsg:4326 >> >> I'm testing my mapscript parameters using a simple "mode=map" >> call to Mapserver, and the results I'm getting so far don't >> match the appearance of the WMS output at all. My mapfile has >> the following extent and projection info in it: >> >> PROJECTION >> "init=epsg:4326" >> END >> >> EXTENT -125.0 39.0 -108.0 54.0 >> SIZE 600 600 >> >> In addition to the mapfile projection specification, I am also >> specifying the same projection info in each of my LAYERS as well. >> >> Is it possible to do what I'm trying to accomplish here? >> >> Thanks, >> >> Roger >> -- >> >> >> ------------------------------------------------------------------------ >> >> _______________________________________________ >> mapserver-users mailing list >> mapserver-users@lists.osgeo.org >> <mailto:mapserver-users@lists.osgeo.org> >> http://lists.osgeo.org/mailman/listinfo/mapserver-users >> >> >> -- >> Julien-Samuel Lacroix >> Mapgears >> http://www.mapgears.com/ >> >> _______________________________________________ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users