Re: GDAL NetCDF driver and projection.

• To: galeon@xxxxxxxxxxxxxxxx
• Subject: Re: GDAL NetCDF driver and projection.
• From: "Rob Cermak" <cermak@xxxxxxxxxxxx>
• Date: Wed, 26 Apr 2006 07:09:52 -0800 (AKDT)

Hi Denis,

Here are some notes on what was planned for storing projection, etc in
other parts of GDAL drivers.  To my knowledge, the never really propogated
through to the OPeNDAP driver.  If the NetCDF or HDF direct access GDAL
driver is updated that those changes propogate through to the OPeNDAP
driver so that the same NetCDF/HDF datasets are accessible via native
OPeNDAP server, Grads GDS and THREDDS.

At this point, a lot more support is there for local NetCDF/HDF files than
for support of those files through OPeNDAP.   Its on my rather large to do
list, but somewhere in the 2 year timeframe.

http://home.gdal.org/~warmerda/gdal_opendap_design.html (GeoTiff)
http://gdal.maptools.org/frmt_dods.html (DODS/OPeNDAP)

Thanks!
Rob

On Wed, April 26, 2006 5:32 am, Denis Nadeau wrote:

Hi All,

I would like to have suggestions from the community on the current needs
for the GDAL NetCDF driver.  I am currently writing the CreateCopy method to
allow people to convert from any GDAL supported format to NetCDF CF-1
convention format.

At this point I am stuck with projection issues.  How should I handle
DATUM,
SPHEROID and AUTHORITY?  I can produce a lat lon arrays to reproject the
projected coordinates to lat/lon space but that may be expensive in cpu
and
space.

I am thinking as well to create an array containning the GeoTransform
values
if found in the source file.

     adfGeoTransform[0] /* top left x */
     adfGeoTransform[1] /* w-e pixel resolution */
     adfGeoTransform[2] /* rotation, 0 if image is "north up" */
     adfGeoTransform[3] /* top left y */
     adfGeoTransform[4] /* rotation, 0 if image is "north up" */
     adfGeoTransform[5] /* n-s pixel resolution */


Thanks for your suggestion,

Best Regards,
Denis Nadeau

--
Alaska Ocean Observing System
Database Manager
907-474-7948

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