[wfs-dev] RE: Axis Ordering in GML

[Jeff Fitzgerald]

Going back to the spec (2.1.x anyway), the gml:coord and gml:coordinates
elements don't have any knowledge of a coordinate system, since they don't
have an srsName attribute. In the spec, they show an example of a gml:coord
element and its equivalent gml:coordinates element. The example implies the
order should be (x,y) or in the case of EPSG:4326 (lon, lat).

<Point srsName="http://www.opengis.net/gml/srs/epsg.xml#4326">
<coord><X>5.0</X><Y>40.0</Y></coord>
</Point>

This would allow the Point example provided above to be encoded as:

<Point srsName="http://www.opengis.net/gml/srs/epsg.xml#4326">
<coordinates>5.0,40.0</coordinates>
</Point>



----- Original Message -----
From: "Martin Daly" <Martin.Daly at cadcorp.com>
To: <wfs-dev at opengeospatial.org>
Cc: "PostGIS Development Discussion"
<postgis-devel at postgis.refractions.net>; <sfsql.rwg at opengeospatial.org>
Sent: Friday, May 20, 2005 4:18 AM
Subject: [wfs-dev] RE: 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.
>
> Oh no, not again.  Do you *any* idea what you have just started?
>
> > 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?
>
> Cadcorp's experience is that the theory is lat/lon, but the practice is
> lon/lat.  Another worm squirming out of the can is that the
> representation of ordinates in EPSG 4326 is not supposed to be in
> decimal degrees.  There are differences of opinion (!) as to whether or
> not this applies to data transfer mediums, or just to user-facing
> representation.
>
> Let battle commence,
> Martin
>
> _______________________________________________
> wfs-dev mailing list
> wfs-dev at opengeospatial.org
> https://mail.opengeospatial.org/mailman/listinfo/wfs-dev
>