[geotk] Mapping coordinate system axis order to i, j indices on a map images

[Jonathan Blower]

Hi,

I'm not sure whether this is a Geotk question, or one for the WMS/ISO
19111 community.  Given a general 2D coordinate system, how do I know
which axis should map to the horizontal dimension of a map image, and
which axis should map to the vertical?  For example, EPSG:4326 uses
lat/lon order, whereas CRS:84 uses lon/lat, but in both cases one would
reasonably expect longitude to map to the horizontal direction.
However, I don't know how a computer would make this inference.

The WMS spec states "Coordinates shall be listed in the order defined by
the CRS and shall be mapped appropriately to the Map CS i and j axes,
*swapping axis order as needed during the projection operation*.

Is there anything in the Geotk API (or even in GeoAPI) that defines when
the axis order shall be swapped?  Or is this really up to applications?

Thanks,
Jon 

--
Dr Jon Blower
Technical Director, Reading e-Science Centre
Environmental Systems Science Centre
University of Reading
Harry Pitt Building, 3 Earley Gate
Reading RG6 6AL. UK
Tel: +44 (0)118 378 5213
Fax: +44 (0)118 378 6413
j.d.blower at reading.ac.uk
http://www.nerc-essc.ac.uk/People/Staff/Blower_J.htm