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Re: 980320: HDF to NetCDF conversion?

>From: William Collins <address@hidden>
>Subject: HDF to NetCDF conversion?
>Organization: NCAR/CGD
>Keywords: 199803201536.IAA15971 netCDF HDF

Hi Bill,

> Sorry, but searches of the resources listed in the
> Scientific Data Format Information FAQ webpage came up empty...
> 
> 
> Are you aware of tools to convert HDF to NetCDF?  I know
> that HDF has tools for reading NetCDF, but I'd like to
> go the other way, since I'm conversant in NetCDF but do
> know HDF at all.  Could NCL do the trick?

It might not be possible to convert *general* HDF data to netCDF data in
any straightforward way, because the data models are not the same.  For
example, if the HDF data made heavy use of vdata and vgroup APIs to
represent hierarchical data structures such as trees, the netCDF
representation in terms of multidimensional variables would require some
extra conventions.

However, I believe it is possible to use NCL to read in HDF data and
then write it out in netCDF form, as long as it conforms to the netCDF
data model.

Another possibility is DDI, a package from LLNL that's freely available
and described at

  http://www-pcmdi.llnl.gov/software/ddi/

It claims to be able to read and write HDF and netCDF, but we haven't
ever installed it here to try it.

Also, the HDF 4.x (I think the latest is 4.1 release 2) library does
contain support for reading data with the netCDF-2 interfaces from
netCDF files in the Unidata file format and for reading and writing
through the netCDF-2 interfaces in the HDF format.  So it might be
practical to create a program that reads an HDF file using an HDF
interface and writes the data in an HDF-encoded netCDF file using the
netCDF-2 interfaces in HDF.  The resulting file would be an HDF file,
but one you could still access data from using netCDF-2 interfaces.

Now that I read it, that sounds pretty complicated ...

Anyway, good luck, and please let us know what the easiest thing you
find is ...

--Russ

_____________________________________________________________________

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