[mapserver-users] WMS Client changes slightly BBOX

[Worth Lutz]

Peter,

I have found that if the map size (width and height in pixels) aspect 
ratio does not exactly match the map extents (map units) aspect ratio 
the map extents are adjusted.

I'm working with MapScript and to get exact scale pdf map I have to set 
map size first and then extent and then scale to get good results.

I hope this helps.


*Worth Lutz*
------------------

On 07/24/2014 06:49 AM, Peter Hopfgartner wrote:
> I'm generating dynamically Map Object, with with a certain extent, in 
> the concrete example
> 629396.05065523,4984079.9894638,655192.92565523,5019084.3644638
>
> In generated Map object uses the WMS client functionality to call WMS 
> services. Anyway, the BBOX get's slightly changed, so that the 
> original scale of 1:100000 gets changed to approx 1:100103, since it 
> calls the WMS services with
> 629382.807906257,4984062.02007212,655206.168404203,5019102.33385548
> as can be taken from the web server log files:
>
> mmm.mmm.mmm.mmm - - [24/Jul/2014:12:25:58 +0200] "GET 
> /author/services/ows.php?PROJECT=ancitel&MAP=catasto_reti&LANG=xw&OGSTAT=ot3cp0i7qmph4guuof75702m70&RESOLUTION=96&LAYERS=dtm,uso_lombardia,strade_lombardia,g_limiti_amministrativi,g_label,g_0707,g_0704&REQUEST=GetMap&SERVICE=WMS&FORMAT=image/png%3B+mode%3D8bit&STYLES=,,,,,,&HEIGHT=1323&VERSION=1.1.1&SRS=EPSG:32632&WIDTH=975&BBOX=629382.807906257,4984062.02007212,655206.168404203,5019102.33385548&TRANSPARENT=TRUE&EXCEPTIONS=application/vnd.ogc.se_inimage 
> HTTP/1.1" 200 678803 "-" "MapServer/6.4.1 libcurl/7.19.7"
>
> This change in scale is beyound te axpected tolerance in this 
> particular use case, where technical data must be plotted in a PDF file.
>
> Any help is appreciated. Obvioulsly, I can fetch the WMS services in 
> my code and overlay them "by hand". Anyway, for a couple of reasons 
> this was the preferred approach.
>
> Regards,
>
> Peter
>
>
>
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