[wfs-dev] Axis Ordering in GML

[Morris, Charles, E.]

All the WFS test data for CITE uses EPSG:32615 so the CITE tests really don't shed any light on the EPSG:4326 interpretation controversy.  

Chuck Morris
Northrop Grumman IT, TASC

-----Original Message-----
From: wfs-dev-bounces+chuck.morris=ngc.com at opengeospatial.org
[mailto:wfs-dev-bounces+chuck.morris=ngc.com at opengeospatial.org]On
Behalf Of Paul Ramsey
Sent: Friday, May 20, 2005 11:07 AM
To: Simon Cox
Cc: wfs-dev at mail.opengeospatial.org
Subject: Re: [wfs-dev] Axis Ordering in GML


Geoserver also does the "wrong" thing. Geoserver passes the CITE tests. 
Geoserver is therefore (as far as the implementors can tell) "conformant".

This detail of implementation is sufficiently obscure that implementors 
seem to be universally failing to do it. So either the specs need a big 
red warning message on the front, or the OGC needs to adopt the 
implementation bias (easting/northing) as official and (again) say so in 
every spec.

I really could care less about the issue in terms of which way is the 
"one true way" I just want everyone to implement the same damn thing so 
I can write a client that interoperates with everybodies servers and 
doesn't need special-cases to determine the vendor and behavior for 
every WFS under the sun.

P.

Simon Cox wrote:
> Not legal because it suggests a latitude of -172.335 when the 
> permissible range for latitude in EPSG:4326 is 90:00:00.00S - 
> 90:00:00.00N, etc etc.
> 
> Strictly this is *not* a GML issue - the gml:coordinates element is 
> merely a character string, so the example is "valid" XML/GML.
> Its just that the example given is strictly meaningless.
> It is a "truth in advertising issue" - if you claim to be using a 
> particular reference system, and then the value you provide is 
> ill-formed & out of range, then you are *not* really using that CRS.
> 
> Unfortunately the three WFS's are telling porkies!
> The sooner they stop then the sooner we could put this one to bed.
> 
> Simon
> 
> ----- Original Message ----- From: "Paul Ramsey" <pramsey at refractions.net>
> To: <Simon.Cox at csiro.au>
> Cc: <wfs-dev at mail.opengeospatial.org>
> Sent: Friday, May 20, 2005 10:21 PM
> Subject: Re: [wfs-dev] Axis Ordering in GML
> 
> 
>> Quick clarification:
>>
>>   Not legal in GML3 or in GML2 (WFS 1.0) or both?
>>
>> It is GML2 I am concerned about. I have results from three WFS servers 
>> so far (Mapserver, Cubewerx, Intergraph) and all are returning 4326 
>> data in easting/northing order. A de facto implementation standard 
>> seems to be emerging. I want to hear what implementors have done for 
>> WFS 1.0, if possible!
>>
>> Thanks,
>>
>> Paul
>>
>> On 19-May-05, at 6:33 PM, <Simon.Cox at csiro.au> wrote:
>>
>>> No - it is not legal.
>>> The main reason is the one you identify - as will all other coordinate
>>> reference system definitions, EPSG 4326 does specify the axis order, and
>>> as with all traditional geographic systems, the axis order is
>>> latitude-longitude.
>>> Furthermore, I think 4326 specifies DMSH as the encoding, though this
>>> aspect might have been relaxed.
>>> It is in fact not a GML issue, but is an EPSG issue.
>>> GML inherits the rules provided by the organisation that are providing
>>> the definition of the CRS.
>>>
>>> Two other issues:
>>> 1. "EPSG:4326" is not a valid URI. In Document 05-010 OGC has defined a
>>> URN scheme that is defined to refer to thing that you are trying to
>>> point to. In this case it would be urn:ogc:def:crs:EPSG:6.3:4326
>>> 2. the gml:coordinates element is deprecated in GML 3.0 and beyond. Use
>>> gml:pos instead, with spaces between the components instead of comma.
>>>
>>> Simon
>>>
>>>> -----Original Message-----
>>>> From: wfs-dev-bounces+simon.cox=csiro.au at opengeospatial.org
>>>> [mailto:wfs-dev-bounces+simon.cox=csiro.au at opengeospatial.org]
>>>>  On Behalf Of Paul Ramsey
>>>> Sent: Thursday, 19 May 2005 11:50 PM
>>>> To: wfs-dev at mail.opengeospatial.org
>>>> Subject: [wfs-dev] Axis Ordering in GML
>>>>
>>>> Question for the group. Is the GML below legal?
>>>>
>>>> <gml:Point
>>>> srsName="EPSG:4326"><gml:coordinates>-172.335,18.53916667</gml
>>>> :coordinates></gml:Point>
>>>>
>>>> I have built a GML point that references EPSG:4326 but has
>>>> the easting before the northing.
>>>>
>>>> If I check your WFS 1.0 servers, will I find them returning
>>>> GML in easting/northing order or northing/easting order for
>>>> EPSG:4326? This is both a theory and practice problem. In
>>>> theory, what should happen, and in practice, what are people doing?
>>>>
>>>> Paul
>>>> _______________________________________________
>>>> wfs-dev mailing list
>>>> wfs-dev at opengeospatial.org
>>>> https://mail.opengeospatial.org/mailman/listinfo/wfs-dev
>>>>
>>
> 
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