[mapserver-users] Problems with non-square pixels

[Michael Pfeiffer]

Hi everybody,

we have problems with one of our WMS services.
The wms services delivers a map for our printing tool.
Map extents from A1-A4 are working fine and fast.
As a example try these two wms requests:

http://www.sogis1.so.ch/cgi-bin/sogis/sogis_print_test.wms?SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&FORMAT=image/jpeg&LAYERS=Orthofoto&STYLES=&TRANSPARENT=true&BBOX=605110.844342816,226276.93355594442,609035.4971205938,229116.79466705554&WIDTH=6181&HEIGHT=4472&SRS=EPSG:21781
A1 landscape 

http://www.sogis1.so.ch/cgi-bin/sogis/sogis_print_test.wms?SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&FORMAT=image/jpeg&LAYERS=Orthofoto&STYLES=&TRANSPARENT=true&BBOX=605653.2401761494,225734.5377226111,608493.1012872604,229659.19050038885&WIDTH=4472&HEIGHT=6181&SRS=EPSG:21781
A1 portrait 

But with A0 map extent we have problems.
Landscape is still working fine. Try this wms request. The map should be
displayed after ca. 10 seconds in your browser.

http://www.sogis1.so.ch/cgi-bin/sogis/sogis_print_test.wms?SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&FORMAT=image/jpeg&LAYERS=Orthofoto&STYLES=&TRANSPARENT=true&BBOX=604241.2471205938,225659.57244483332,609905.094342816,229734.15577816663&WIDTH=8921&HEIGHT=6417&SRS=EPSG:21781
A0 landscape 

In contrast portrait needs now much longer than landscape. From A1-A4 it
needs exactly the same time.

Try this wms request

http://www.sogis1.so.ch/cgi-bin/sogis/sogis_print_test.wms?SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&FORMAT=image/jpeg&LAYERS=Orthofoto&STYLES=&TRANSPARENT=true&BBOX=605035.8790650383,224864.94050038885,609110.4623983715,230528.7877226111&WIDTH=6417&HEIGHT=8921&SRS=EPSG:21781
A0 portrait 

This request needs over 1 minute.
It seems that mapserver gets in the non-square pixels mode for this request.
See the outcome of the Debugger for the request

[Thu Jul 16 11:59:59 2009].111090 msWMSLoadGetMapParams(): enabling
non-square pixels.[Thu Jul 16 11:59:59 2009].452278 msDrawMap(): kicking
into non-squarepixel preserving mode.[Thu Jul 16 11:59:59 2009].452334
msDrawRasterLayerLow(Orthofoto07): entering.
[Thu Jul 16 12:01:15 2009].757262 msDrawMap(): Layer 1 (Orthofoto07),
76.305s
[Thu Jul 16 12:01:15 2009].757304 msDrawMap(): Drawing Label Cache, 0.000s
[Thu Jul 16 12:01:15 2009].757313 msDrawMap() total time: 76.638s
[Thu Jul 16 12:01:41 2009].955410 msSaveImage() total time: 26.198s
[Thu Jul 16 12:01:41 2009].956887 mapserv request processing time (msLoadMap
not incl.): 102.846s
[Thu Jul 16 12:01:41 2009].956896 msFreeMap(): freeing map at 0x82c1688.

In all the other wms requests mapserver does not enable non square pixels

[Thu Jul 16 13:00:47 2009].107521 msDrawRasterLayerLow(Orthofoto07):
entering.
[Thu Jul 16 13:00:49 2009].925029 msDrawMap(): Layer 1 (Orthofoto07), 2.818s
[Thu Jul 16 13:00:49 2009].925076 msDrawMap(): Drawing Label Cache, 0.000s
[Thu Jul 16 13:00:49 2009].925085 msDrawMap() total time: 3.160s
[Thu Jul 16 13:00:52 2009].543021 msSaveImage() total time: 2.618s
[Thu Jul 16 13:00:52 2009].544066 mapserv request processing time (msLoadMap
not incl.): 5.787s
[Thu Jul 16 13:00:52 2009].544073 msFreeMap(): freeing map at 0x8486740.

So the question for me is: Why is this happening?
I think the ratio is OK. Width and height are the same. I only swap them
between portrait and landscape.
I've tried with CONFIG "MS_NONSQUARE" NO and with CONFIG "MS_NONSQUARE" YES
but nothing changed

Any help is much appreciated.

We're using MapServer 5.2.1 with an apache server on Linux
I've attached the mapfile of the WMS.

http://n2.nabble.com/file/n3268002/wms_print_test.map wms_print_test.map 

The relevant layers are Orthofoto07 and Orthofoto5m

thx for the help

Michael

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