[Geojson] [OSGeo-Standards] EPSG + Coordinate Ordering (Was Re: GeoJSON '1.0'?)

[Christopher Schmidt]

On Fri, Mar 14, 2008 at 09:29:58AM -0400, Frank Warmerdam wrote:
> Chris,
> 
> I think I have got lost here somewhere.
> 
> Yes, a complete CRS definition tells what maps to X, what maps to Y,etc.

Apparently, EPSG:4326 *doesn't* do that: The CRS doesn't have a
cartesianCS, which means that it doesn't define the mapping to X,Y, at
least not explicitly.

> For instance EPSG:4326 defines that X is latitude and Y is longitude.

Not according to the GML:
http://www.epsg-registry.org/export.htm?gml=urn:x-ogc:def:cs:EPSG:6422
says "Latitude is first", not "Latitude is X", no? (6422 comes from
http://www.epsg-registry.org/export.htm?gml=urn:x-ogc:def:crs:EPSG:4326
.)

> So what is proposed (I assume) for GeoJSON is that we override some set
> of EPSG CRS definitions so they map longitude to X and latitude to Y.
> Isn't that right?

I don't think there's any claim that "Latitude is X", so I don't think
so.

Okay, according to mpd, I'm wrong: mpd says that there is an *implied*
claim that "Lat is X" -- which means that my entire argument just went
out the window, and you're right. However, I didn't knwo that until
about 30 seconds ago.

This essentially makes my entire position totally bunk.  So, any
argument I've made in this discussion is based on incorrect
understanding, and should be ignored.

> Anyways, it would appear my little screed on x, y, z was not addressing
> a real problem so I'll back off on that.  You seem to have a good grasp
> of the issues.

I doubt that :) I'm just learning a little more every time this comes
up.

Regards,
-- 
Christopher Schmidt
MetaCarta