Scientific Data Formats Overview
This section provides an overview the four self-describing scientific data formats supported by IDL: CDF (Common Data Format), HDF and HDF5 (Hierarchical Data Format), HDF-EOS (Earth Observing System extensions to HDF), and netCDF (Network Common Data Format). These data formats are supported on all IDL platforms. Detailed documentation for each routine can be found in this volume.
CDF—Common Data Format
The Common Data Format is a file format that facilitates the storage and retrieval of multi-dimensional scientific data. This version of IDL supports CDF 3.2. IDL's CDF routines all begin with the prefix "CDF_".
CDF is a product of the National Space Science Data Center (NSSDC). General information about CDF, including the "frequently-asked-questions" (FAQ) list, software, and CDF's IDL library (an alternative interface between CDF and IDL) are available on the World Wide Web at:
If you do not have access to the WWW you can get CDF information via ftp at:
For assistance via e-mail, send a message to the internet address:
HDF—Hierarchical Data Format
The Hierarchical Data Format (HDF) is a multi-object file format that facilitates the transfer of various types of data between machines and operating systems. HDF is a product of the National Center for Supercomputing Applications (NCSA). HDF is designed to be flexible, portable, self-describing and easily extensible for future enhancements or compatibility with other standard formats. The HDF library contains interfaces for storing and retrieving images and multi-dimensional scientific data.
IDL supports two distinct versions of HDF: version 4 and version 5.
HDF Version 4 Support
This version of IDL supports HDF 4.2r3. IDL's HDF version 4 routines all begin with the prefix "HDF_".
HDF Version 5 Support
This version of IDL supports HDF5 5-1.6.7. IDL's HDF version 5 routines all begin with the prefix "H5_" or "H5*_".
Further information about HDF and HDF5 can be found on the World Wide Web at the HDF Information Server:
Alternately, you can send e-mail to hdfhelp@ncsa.uiuc.edu.
HDF-EOS—Hierarchical Data Format - Earth Observing System
HDF-EOS (Hierarchical Data Format-Earth Observing System) is an extension of NCSA (National Center for Supercomputing Applications) HDF and uses HDF calls as an underlying basis. This API contains functionality for creating, accessing and manipulating Grid, Point and Swath structures. IDL's HDF-EOS routines all begin with the prefix "EOS_". This version of IDL supports HDF-EOS 2.8.
HDF-EOS is a product of NASA, information may be found at:
NetCDF—Network Common Data Format
The network Common Data Format (netCDF) is a self-describing scientific data access interface and library developed at the Unidata Program Center in Boulder, Colorado. The netCDF interface and library use XDR (eXternal Data Representation) to make the data format machine-independent. This version of IDL supports netCDF 3.5. IDL's NetCDF routines all begin with the prefix "NCDF_".
More information about netCDF can be found on Unidata's netCDF World Wide Web home page which can be found at:
Further information and the original netCDF documentation can be obtained from Unidata at the following addresses:
UCAR Unidata Program Center
P.O. Box 3000
Boulder, Colorado, USA 80307
(303) 497-8644
e-mail: support@unidata.ucar.edu
