Using non EPSG CRS is neater, but at odds with practice and leaves an
authority hole...
IMHO the only hope of reconciling these things is to state that the OGC
recognises EPSG as the authority for the geometry definition, not the
representation (serialisation) rules, and that should be reinforced by
adding an explicit mechanism to handle specification of serialisation
rules for a CRS.
I'm not sure too many people respect the DMS serialisation requirement
either.
See:
http://www.*epsg*.org/guides/docs/G7-1.pdf
Why isnt axis order simply part of the "degrees representation" issue?
Yes, its seems more complex to handle concerns separately, but its so
much simpler in the long run!
Rob A
Martin Desruisseaux wrote:
Adrian Custer a écrit :
Any chance you could write up a paragraph explaining what's going on
with axis order? I'm assembling notes for an eventual writeup of the
geotools CRS and this seems like an important corner case. The EPSG
CRS's are all in the lat, long order except for 4326 which is long, lat?
Not exactly. In the EPSG database, the axis order is
(latitude,longitude) for most geographic CRS, including EPSG:4326. The
problem is that common usage in the field (derived from early WMS
specification, as explained by Jody) expect (longitude,latitude)
order, in violation of what EPSG said.
EPSG:4326 was just cited as an example, but the problem apply to about
all geographic CRS defined in the EPSG database. Axis order used in
the field (from early OGC WMS specification) for "EPSG:4326" (and
other geographic CRS) are in violation with the real axis order
defined in the EPSG database.
It has been proposed that "EPSG:4326" means "CRS with axis order as
defined by OGC, not by EPSG", which seems to me a door opened for
confusion since the CRS is called "EPSG:...", which suggest a CRS
defined by the EPSG authority...
An other problem is that "EPSG:4326" as defined by OGC would be
inconsistent with usage of "4326" in the EPSG database itself (for
example the "source" and "target" CRS relations in the
"Coordinate_Operations" table).
Martin.
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