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EOS-IT: A Data Imaging and Subsetting Tool

The HDF-EOS Imaging Tool (EOS-IT) is a dual mode interface that provides an easy way to compare and analyze data from a variety of data sets. In the first mode, called Georeferenced Viewing, the tool reads any file containing data in swath or Lambert Azimuthal Equal Area grid projection and displays these data in multiple linked, georeferenced Image Windows. Using the Georeferenced Viewing mode, you can also view core metadata and structural metadata, overlay coastlines in zoom windows, and see a range of data cells in a table marked by pixel location in the corresponding image. In the second mode, called Bitwise Viewing, it reads HDF-EOS grid and swath data and allows you to examine individual bits from data fields in those files. The two modes can be used simultaneously.

The two modes of EOS-IT provide greater functionality than other HDF tools currently available. Other tools have a limited ability to decode and display information stored as individual bits. Many MODIS products, for example, have pixel-level quality assessment arrays in one or more 8-bit words. Most visualization programs read and display these arrays as 1-byte words with 256 possible values. EOS-IT allows you to select and view the information in each bit separately or in user-specified combinations.

To make EOS-IT cross-platform compatible, it was written in Interactive Data Language (IDL). Users must have IDL 5.6 installed to run EOS-IT.

The National Snow and Ice Data Center distributes the EOS-IT tool to assist users working with polar gridded data sets in HDF-EOS, including the MODIS Level 3 sea ice product. Download the program, documentation and source code from:

For help, questions or comments, please contact NSIDC User Services.