[gdal-dev] Re: gdal-dev Digest, Vol 44, Issue 28

[Frank Warmerdam]

Craig Leat wrote:
> AFAIK, to support the South African datums (EPSG codes: 22275, 22277,
> 22279, ..., 22293 and 2046 to 2055) axis order and axis orientation
> switches are required. Could this RFC be expanded to allow support for
> these datums?

Craig,

22279...22293 are projected coordinate systems.  It is my intention
to support axis ordering for projected coordinate systems as well
as geographic coordinate systems, though it is possible this may be
delayed a bit.

It looks like 2046 to 2055 are also projected coordinate systems.

Note, my work is not necessarily going to address handling of the
Transverse Mercator South Orientated projection method used in these
projected coordinate systems.  I'm still a bit confused about TMSO to
be honest.

> Frank when we discussed this 18 months ago you wrote the following:
> "My intention for addressing this was to add some sort of +axis...
> directives that would tell the pj_transform() function how axis values
> need to be remapped.  So, it would require extending the PJ structure
> with the axis info, and modifications to pj_transform to apply it,
> converting stuff into internal form on the way in, and back to
> external form on the way out."
> 
> I am not familiar with the API so please excuse me if I have missed the point.

The RFC covers an "all in GDAL/OGR" solution, mostly so it won't be
necessary to have a particular version of PROJ.4 for axis stuff to
work properly.  Someday I may also add the axis support described in
the paragraph above in PROJ.4, but I would presumably avoid using it
from GDAL even then.

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    | President OSGeo, http://osgeo.org