Re: [Geotools-devel] problems with coordinate system flipping

[Rob A. <ro...@so...>]

ahh - this is serius issue in the specifications front...

I think the behaviour is correct.

The OGC specifies that the urn: referenced coordinate systems should 
always be interpreted as Lon/lat order, in conformance to the EPSG 
"definition" - though they dont also specify that it should be in 
Degrees/Minutes/Seconds which EPSG also states.
I argued at the time that coordinated  was not part of the _definition_ 
but a _presentation rule_ and its nonsensical to choose an arbitrary 
piece ofthe presentation as part of the definition..

So. EPSG:4326 is not the same as

urn:x-ogc:def:crs:EPSG:6.11.2:4326

Only EPSG:4326 should be interpreted according to WMS version. I cant remember right now whether there was an explicit rule for GML 2 vs 3, WFS 1.0 vs 1.1.

The European INSPIRE program is going to mandate WMS 1.3, every known WMS supports 1.1 because its too hard to work out what you should be doing for 1.3 (how should a getFeatureInfo response be encoded?)

Actual practice seems to be, if people are using 
urn:x-ogc:def:crs:EPSG:6.11.2:4326

then they will also encode the lon/lat ordering, otherwise they will use the more natural lat/lon.

So, the flag only applying to EPSG codes, probably only for specific protocol versions, is best behaviour in such a crazy world.

Rob A

Justin Deoliveira wrote:
> Hi Martin,
>
> I am not sure but I think Andrea may have brought this issue up with you
> before. But he is on vacation at the moment so I will ask you.
>
> The problem that I am running into is that in GeoServer we use the hint
> the to switch the axis of 4326. However when a WFS request comes in with
> the srsName of:
>
> "urn:x-ogc:def:crs:EPSG:6.11.2:4326"
>
> The hint does not seem to apply and the coordinate system axis are not
> swapped. This is a problem because it retults in a conversion between
> the two and all geometry x,y values are swapped.
>
> I seem to remember this being a problem with the hints not applying to
> an adapter of some sort?
>
> Any idea Martin?
>
> Thanks,
>
> -Justin
>
>