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SWA - Hierarchical Data Format (HDF)Background * Tutorial * Links BackgroundThe NASA ESDIS project selected the Hierarchical Data Format (HDF) as the common data format of choice for standard product exchange and distribution. As developed by the National Center for Supercomputer Applications (NCSA), the HDF format is supported by a collection of software routines and applications needed to work with data sets in HDF. This set of software, referred to as the HDF library, is available in the public domain. To facilitate the exchange of data and data products generated by current (TERRA) and upcoming Earth Observing System (EOS) missions (such as AQUA and AURA), as well as satellite missions such as TRMM, a sub-library or library extension of HDF, called HDF-EOS, has been developed for the EOSDIS Core System (ECS) by the Raytheon Systems Corporation (RSC). HDF-EOS was developed to specifically deal with the types of satellite and field campaign data products that are and will be routinely generated by EOS missions but which are not fully supported by the base HDF library. While there are many advantages to the use of HDF and HDF-EOS, a key to their success as a common data format and software library may be dependent upon expanding the general user and science communities' awareness, knowledge, and comfort with HDF and HDF-EOS. In particular, it is the individual investigators, academia (students through researchers), the educational community, and the general public that many times do not have the required knowledge, nor the resources to commit to obtaining this knowledge, to work with HDF and HDF-EOS files.
Online HDF and HDF-EOS TutorialsIn response to this need, the NASA ESDIS project has funded the creation of several on-line tutorials geared towards HDF and HDF-EOS beginners. The initial tutorial dealt specifically with the HDF library and format. A
Microsoft Word version of the tutorial may be downloaded from the below links:
The purpose of this current and updated tutorial is to provide the non-expert, particularly potential future users and producers of EOS data, with the necessary information to enable one to learn about both HDF AND HDF-EOS and to successfully browse, read and write data sets in HDF format. This information will include, but not be limited to, sections on the basics of HDF/HDF-EOS and HDF/HDF-EOS files, the required software/hardware, the various ways of working with the files, a review of HDF and HDF-EOS commands and operations, and instructions and advice for writing programs to work with HDF and HDF-EOS. A portion of the information presented here can also be found in much further detail scattered throughout various other literature and several of the excellent reference guides and manuals (more on this in Section 2- An Introduction to HDF and Section 3- An Introduction to HDF-EOS) written by NCSA for HDF and by RSC for HDF-EOS. However, the goal of this tutorial is to present, in a concise and easy to understand form, only the information needed to help the HDF novice to browse, read and write basic HDF/HDF-EOS files. More importantly, as they are certainly linked, it is the goal of this tutorial to combine the information on both HDF and HDF-EOS under one encompassing document. Furthermore, the HDF library has been designed to work with many different types of data (arrays, images, etc.) and to carry out both simple and complex operations on data sets. As a teaching tool, this tutorial will concentrate on only several selected data types supported by HDF (images, palettes, scientific data arrays) and HDF-EOS (Point, grid, and swath) libraries, and the basic operations such as reading, writing, and browsing entire data sets. The user will be directed to the some of the most critical documentation to learn about all the various operations and data types supported by HDF and HDF-EOS. The current version of this HDF and HDF-EOS tutorial concentrates on the latest release of the HDF library (HDF 4.1r3 as of July 2000) and HDF-EOS sub-library (HDF-EOS 2.6 as of June 2000), and how to use them for browsing, reading and writing HDF files containing scientific data arrays, raster images with associated palettes; and point, swath, and gridded HDF-EOS data sets. Viewing the Tutorial
Modifications to the tutorial are ongoing. Comments are welcome and should be sent to Steven Greco.
Other HDF Resources
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