Re: DODS & Accessing HDF format

[Steve Hankin <hankin@xxxxxxxxxxxxx>]

Hi Frederic,

Ferret accesses HDF files from the PODAAC at JPL just fine via DODS. If you
have an HDF DODS server on your local machine with the directory paths set
up appropriately Ferret should perform just the same on local files. You'll
need to use a path of  "http://localhost/DODS_server_path/my_file.hdf";.

As an example of DODS HDF access try these commands:

     USE
     "http://dods.jpl.nasa.gov/cgi-bin/nph-hdf/pub/ocean_wind/ssmi/atlas_ssmi/hdf/data/level3.5_5day/1996/atlas.ssmi.ver02.level3.5_5day.s960103.hdf";

     define axis/x=-180:177.5:2.5/units=degrees xjpl
     define axis/y=-90:90:2/units=degrees yjpl
     define axis/t="1-jan-1996":"31-dec-1996":5/units=days tjpl
     define grid/x=xjpl/y=yjpl/t=tjpl gjpl
     let jpl_u10m = u10m[g=gjpl@asn]
     PLOT/t=1-dec-1995:1-dec-1997  jpl_u10m[x=165e,y=0]

Notes:

   * The USE command may take a few moments to initialize the remote data
     set -- a feature of DODS that will be improved in the next Ferret
     release
   * The HDF file does not contain coordinates -- hence the additional
     Ferret commands to create a grid
   * There are many variants on HDF ... it is possible that some will
     reveal problems. I can put you in touch with someone who knows more
     about this if interested in pursuing it.

    - steve

Frederic Chagnon wrote:

> Hi-
>
> Has anyone had experience with using the DODS capabilities of Ferret to
> access a locally stored HDF file?
>
> Any help would be much appreciated.
>
> -Frederic
>
> ---------------------------------------------------
> Frederic Chagnon                   frederic@mit.edu
> Ralph M. Parsons Lab  48-114         (617) 253-5450
> Massachusetts Institute of Technology

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