Ahh I see now that I have misunderstood the ticket.

Agreed that you certainly wouldn't want to change the long standing behaviour 
of Geoserver - that would be very bad karma.

Thanks to you and Jody for the prompt reply and thanks for the work that you 
have put into Geoserver. 

Regards
Ben


----- Original Message -----
From: "Andrea Aime" <[email protected]>
To: "Ben Khoo" <[email protected]>
Cc: "Geoserver-devel" <[email protected]>
Sent: Tuesday, 12 August, 2014 1:22:56 AM
Subject: Re: [Geoserver-devel] GEOS-6420




On Mon, Aug 11, 2014 at 4:51 PM, Ben Khoo < [email protected] > wrote: 


Hi, 

I'd just like to check my understanding of 
https://jira.codehaus.org/browse/GEOS-6420 (WMS GetFeatureInfo does reproject 
the featureMember geometry in GeoServer 2.5) 

According to the issue and documentation 
http://docs.geoserver.org/latest/en/user/services/wms/reference.html it appears 
that the returned geometry should be reprojected into the specified SRS no 
matter the projection of the layer in Geoserver. 



Nope, neither the docs nor the ticket state that explicitly. 


The ticket was about a layer in EPSG:2157, with a request in EPSG:2157, with 
GetFeatureInfo apparenlty 
returning coordinates in lat/lon (I say apparently, because what they were 
actually getting were screen coordinates, 
in pixels). 


The documentation does not contain an example of reprojection either. 


If we go down to the OGC specification, they only say: 


------------------------------ 



Because the WMS protocol is stateless, the GetFeatureInfo request indicates to 
the WMS what map the user is viewing by including 
most of the original GetMap request parameters (all but VERSION and REQUEST). 
From the spatial context 
information (BBOX, CRS, WIDTH, HEIGHT) in that GetMap request, along with the 
I,J position the user chose, 
the WMS can (possibly) return additional information about that position. 
The actual semantics of how a WMS decides what to return more information 
about, or what exactly to return, are 
left up to the WMS provider. 


------------------------------ 



If you look at the GeoServer history, none of "vector" GetFeatureInfo output 
formats ever reprojected the geometries 
in the requested CRS, all of them always returned the geometries in the layer 
native SRS. 


Now, I'm not saying this behavior is correct, but it has been around for almost 
10 years now, which 
means it cannot be changed lightly, as it would break existing clients. 


Now, given than most clients using GetFeatureInfo GML/JSON outputs are 
verticals (since a generic 
WMS client cannot be assuming any such output format), I believe what we could 
do is to add 
either a request parameter, or a admin level setting in the WMS panel (ideally 
both), to make the GetFeatureInfo 
reproject the results to the GetMap target projection 
(contributions/sponsorship to implement this 
are welcomed as usual :-p ) 


Cheers 
Andrea 

-- 




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