[gdal-dev] geolocation info in netCDF: "northernmost_northing" etc. not universal

[Bruce Raup]

GDAL developers,

I am working with netCDF files and GDAL, and we are in the process of
determining the exact format of the netCDF files we will produce for
the public to use.  We are aware of the CF conventions for storing map
parameters in the file, but what seems less well defined is how to
represent the extent of the data in grid coordinates.

The netCDF driver in GDAL appears to use the terms

northernmost_northing
southernmost_northing
westernmost_easting
easternmost_easting

to supply grid boundary coordinates, and I understand the information
in these is redundant with the information stored in the attribute
"GeoRef".

My question is, what would be the impacts of changing these terms to
something that makes sense more universally?  These terms make no
sense (are actually very confusing) in some situations, such as a
south-up map near the south pole.

We propose using terms such as

grid_top_boundary_projected_y
grid_bottom_boundary_projected_y
grid_left_boundary_projected_x
grid_right_boundary_projected_x

Alternatively, grid corner coordinates could be used.

What would the impacts of such a change of names in our files be?  If
the GeoRef field is also in the file, would it break existing software
for being able to navigate (geolocate) the data?  And, would the
community consider the adoption of more universal terms more generally
(i.e. in GDAL itself)?

Thanks,
Bruce Raup