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Re: GDAL netCDF Support

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  • Subject: Re: GDAL netCDF Support
  • Date: Wed, 07 Jan 2004 16:27:22 -0700
Hi Frank,

> At the request of GMT users (primarily netCDF for grids) I have implemented
> support for netCDF import/export in my GDAL library.  GDAL is an open source
> multi-format read/write library for geospatial raster data.
> 
> I am interested in pointers to sample netCDF "grid" files, or cooperation
> from anyone intersted in testing the GDAL netCDF support - especially GMT
> users.

There are some current weather forecast model outputs in netCDF form
available from:

  ftp://ftp.unidata.ucar.edu/pub/netcdf/sample_data/sst_61-64.nc
  ftp://ftp.unidata.ucar.edu/pub/netcdf/sample_data/ruc_211.nc
  ftp://ftp.unidata.ucar.edu/pub/netcdf/sample_data/ocean_21-24.nc
  ftp://ftp.unidata.ucar.edu/pub/netcdf/sample_data/ecmwf_1-12.nc

and lots of other sample netCDF gridded data files in that same
directory.

> It would also be nice to have GDAL (http://www.remotesensing.org/gdal) listed
> in the list of netCDF supporting software packages.

I've put a draft listing at

  http://www.unidata.ucar.edu/packages/netcdf/software.html#GDAL

by plagiarizing your brief description, with a few minor changes to
make it consistent with other listings.  Please let me know if you
want any changes to the draft entry.  Currently netCDF is not listed
in your table of Supported Formats, but I assume you will list it
eventually.

> Lastly, during implementation I have encountered symbol collections
> (nc_findattr() or something similar) with symbols from the HDF (or perhaps
> HDF-EOS) libraries.  Is this a common problem?  Is there an obvious 
> workaround?

I'm not sure what you are referring to here.  The current netCDF
release 3.5.0 or beta release 3.5.1beta13 (soon to be the official
release) don't have any reference to HDF or HDF-EOS libraries, as far
as I know.  In particular, I can't find any reference to
"nc_findattr".  In a separate project, we are developing netCDF-4
using HDF5 as the format layer, but that is not released and not even
available except to a few developers on the project list.  Could you
provide more details about what version of netCDF you are using (in
the src/libsrc/VERSION file of any netCDF source distribution) and the
error messages that show unresolved symbols?  Thanks!

And by the way, on behalf of the netCDF community, thanks very much
for the work required to include netCDF among GDAL's supported
formats.  There's a growing need for the ability to access netCDF data
from GIS systems, and vice versa.  It looks as if what you have done
may be very useful to users in both the GIS and geoscience
communities.

--Russ

_____________________________________________________________________

Russ Rew                                         UCAR Unidata Program
address@hidden          http://www.unidata.ucar.edu/staff/russ