The EPSG Contract

[Frank Warmerdam]

On 5/18/05, Paul Ramsey <pramsey at refractions.net> wrote:
> Daniel,
> 
> I think whether Mapserver is broken is a matter of interpretation. In
> GML 2.1, when a CRS is referred to using an EPSG number, is the full
> EPSG contract implied? If yes, then mapserver is broken: it returns
> EPSG:4326 coordinates in easting/northing order. If no, then mapserver
> is fine.

Paul, 

Certainly my _assumption_ was that GML 2 operated on the basis of 
easting,northing order regardless of what EPSG says.  If you are concerned
I really think you need to get clarification from the WFS and GML folks
on this issue.  If we really need to, we can then hack something into 
MapServer's WFS client and server code to do this properly.

I would add that I do anticipate adding some sort of "axis" directives
to PROJ.4, at least for use with the pj_transform() entry point.  It is
needed for Krovak projection as well as all these lat/long vs. long/lat
items. 
 
> A speak-no-evil, hear-no-evil approach will just lead to sorrow and
> wailing in the future. What we need from OGC is a pretty public and
> solid directive about "what we mean now when we say EPSG:XXXX" and "what
> we meant two years ago when we said EPSG:XXXX". Because the two are not
> necessarily the same.

I would just like to put a vote in for the "speak-no-evil,
hear-no-evil" approach.
I have yet to get past my anger with those who lobbed this compatibility
nightmare into our midst, and I am loath to spend unfunded time dealing with 
it. 

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent