Knowledge Base

Geolocating EASE-Grid Data in ENVI

This article describes how to geolocate North, South, and Global EASE-Grid data from the DMSP SSM/I-SSMIS Pathfinder Daily EASE-Grid Brightness Temperatures product using ENVI software. These procedures were tested with ENVI Classic 5.2 on both linux and Windows 7; other versions of ENVI may have slightly different menu options and steps. 

  1. Download the appropriate ENVI header file (.hdr) from the following list at the bottom of this article to your computer. Choose a header file that corresponds with the projection (north, south, or global (M)) and spatial resolution (12.5 km or 25 km) of your data file, and rename it to match the data file (keeping the .hdr extention). For example, if your Global 25 km EASE-Grid data file is named EASE-F17-MH2020244A-V2.91H, then rename EASE_M25km.hdr to EASE-F17-MH2020244A-V2.91H.hdr. Note: Be sure the header file and data file are in the same directory.
     
  2. Start ENVI, from the main ENVI menu bar, select File --> Open Image File, and select your data file. The Available Bands List window appears and lists the data file. Select Band 1 and click Load Band. The data file displays, and you can confirm the latitude and longitude of each pixel by selecting WINDOW -->Cursor Location/Value from the display window.
     
  3. Now that you have opened a data file using one of the header files from Step 1, you can open any data file with the same spatial resolution and hemisphere using this same header file, as long as the original data file remains open in ENVI. To see how this works, try the following steps.
    1. From the main ENVI menu, select File --> Open Image File and select a new data file.
    2. When the Header Info window appears, click Input Header Info From --> Other File... and select the original data file you opened in Step 2. ENVI uses the same header information to open your new file.