Obtaining the HDF application software
In order to read the TOVS data files, the HDF library must be installed
on your machine.The HDF application software is available at no cost
from the National Center for Supercomputer Applications (NCSA) at the
University of Illinois and the Goddard DISC.Although the DISC site
is mirrored off the NCSA, the DISC houses pre-compiled HDF libraries
and supporting command line executable programs for many UNIX machines.
The command line utilities operate directly on HDF files and the HDF
library module can be linked to user-written Fortran and C programs
which include HDF subroutine calls.
To obtain the HDF library, log into the Goddard DISC's anonymous ftp server using the command:
Name (disc.gsfc.nasa.gov:): anonymous
Password: < your e-mail address >
The README file you have transferred to your system details the
structure of the GDISC `hdf' directory and information on
downloading the current release of the HDF source code library,
currently HDF3.3r4, or if you prefer, the pre-compiled HDF library
appropriate to your machine. Read this carefully to determine what
files you should download for your particular purpose, then log back
into the ftp server and issue the appropriate transfer commands to
obtain these files.
If you have any questions or comments at all concerning these
libraries, please send e-mail to :
Or call the DISC help desk at (301) 614-5224.
A sample session which illustrates how to extract information from
a TOVS Path A HDF file using the command line utility 'hdfed'
(automatically created upon installation of the HDF software) is
shown in the Appendix.
Image Display and Analysis Tools
The NCSA has produced a variety of HDF visualization tools that
display HDF files containing Scientific Data Sets (SDS). The most
popular and versatile package at this time is called Collage. To
obtain the program, log into the NCSA anonymous ftp server using
the command :
ftp ftp.ncsa.uiuc.edu(or ftp 126.96.36.199)
Name (188.8.131.52:): anonymous
Password:<your e-mail address>
Here you find the versions of Collage for the Macintosh, Unix and PC
(Windows) machines. For example, to obtain the `DEC Alpha' Unix
version of Collage, type :
Then set the transfer mode to "binary" and download the required file.
Make sure that you have sufficient disk space on your local machine.
For example, a minimum of about 2.3 Mbytes of space is needed in this
ftp> get collage.alpha.gz
Next download the instructions required to install and use Collage:
ftp> get DOCS
The ".gz" suffix on the file indicates that a special form of storage
has been used (called "compression") to temporarily store the file in
such a way as to conserve disk space. The file must be "uncompressed" and the file protection changed before attempting to use it by issuing
the following Unix commands :
chmod 755 collage.alpha
Use the information in DOCS to become acquainted with the operation
and applications of Collage.
At some point you may want to log back into the NCSA through anonymous
ftp and retrieve the detailed User's Guide for Collage. However, be
aware that this file is very large, close to 62 MBytes compressed.
If you do not have sufficient space to download the User's Guide to
your machine, please contact the Goddard DISC help desk at the phone
number listed in the previous section in order to obtain a hardcopy
version of the Guide.
In addition, a visualization package called VISTAS has been developed
by a group at JPL and designed specifically for use with the level 3
TOVS Pathfinder data. VISTAS allows users to "navigate" the data by
specifying which parameters they would like to visually examine on a
certain date. They will be able to perform basic image processing
functions and animation capabilities that make use of zooming and
scrolling around the data set. Enhancements are planned in later
releases of VISTAS. Currently, VISTAS runs on Sun Sparc Stations
using Sun Operating Systems (OS) 4.1.x and on Silicon Graphics
Workstations using IRIX 5.1.x. To obtain VISTAS, log into the
Goddard DISC anonymous ftp using:
ftp disc.gsfc.nasa.govorftp 184.108.40.206
After obtaining the README, log out of anonymous ftp and consult the
README for a detailed description on obtaining, installing and getting
help on VISTAS. Please refer to section 6 of this document for a list
of contacts for VISTAS software and user support.
Some other public domain and commercial software packages can be used
to view HDF data. They are: EASI/PACE, IDL, and SpyGlass (to obtain
these, see Section 6). Thus far only IDL has been tested by the DISC
for reading and visualizing the TOVS Pathfinder files.