[mapserver-users] Re: EPSG:4326 with WMS 1.3.0

Olivier Terral olivier.terral at geomatys.com
Mon Nov 22 03:37:02 EST 2010


Hi Jukka,

Thanks for your feedback, Jukka. Your explanations are usefull.


Bye

     Olivier

On 21/11/2010 19:11, Vincent Heurteaux wrote:
> Hello Jukka,
> Thank's for your feedback. After a closer look to WMS 1.3.0 specification (OGC 06-042, section 6.7.2 page 15), it appears that you are totally right.
>
> Thank's again,
>
> Vincent
>
> Le 21 nov. 2010 à 16:38, Rahkonen Jukka a écrit :
>
>> vheurteaux wrote:
>>
>>> Hello Jukka,
>>> You said "You may see rotated maps if you open gml vector data returned by
>> WFS 1.1.0 service with a client than can't handle axis flipping but that is
>> a client error".
>>
>>> Do we agree that the server is expected to return a rotated map, and that
>> the client is expected to put it back in the right orientation?
>>
>> Not really, I fear. Even WFS server does not send rotated maps, it is sending normally oriented vector maps with coordinates in order northing-easting with some projections. The vector map client is expected to parse the coordinates correctly by following the projection definitions.  For example UTM zones are always easting-northing and WFS output from versions 1.0.0 and 1.1.0 have the same axis order.
>>
>>> Do we agree that on a client with no such capability (for example when
>> viewing the image directly in the internet browser), the image in EPSG:4326
>> shall appear rotated?
>>
>> WMS is sending images as they should appear on the screen and client is not supposed to do any pixel-by-pixel warping. Only thing that a proper WMS 1.3.0 client need to do is to build BBOX with correct axis order, either easting-northing or northing-easting.  A not-proper WMS 1.3.0 client will build BBOX with wrong axis order (again, with some projections) and get back a north-up image from some other place of the world, not a rotated image.
>>
>> -Jukka Rahkonen-
>>
>>
>>
>> Cheers
>> Vincent
>> -- 
>> View this message in context: http://osgeo-org.1803224.n2.nabble.com/EPSG-4326-with-WMS-1-3-0-tp5756000p5757819.html
>> Sent from the Mapserver - User mailing list archive at Nabble.com.
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