AirMISR L1B2/L2AS Coregistration Tool Readme 1.0 Overview The AirMISR L1B2/L2AS Coregistration Tool was written as an example of how to determine the location of the L2AS Land Surface Product footprint within the L1B2 Georectified Radiance Product data area. The L1B2 and L2AS data have the same pixel size (27.5 m) and pixel location or alignment. The geometric parameter values for the L2AS footprint area, which are available in the L1B2 files, can be extracted from the corresponding L1B2 file once the overlay area is known. The Coregistration Tool displays file selection dialog boxes for specifying the L1B2 and L2AS files of interest. An image is displayed from each of the files to illustrate their respective data areas, and the footprint of the L2AS file is outlined in red on the L1B2 image to show the overlap. Information about the two files is displayed in a text window. The dimensions of the data areas and the upper left and lower right coordinates of the data areas in both Universal Transverse Mercator (UTM) meter values and latitude/longitude values are shown. The L1B2 pixel that corresponds to the upper left of the L2AS footprint is specified by column number and row number. The tool is written in Exelis Visual Information Solutions IDL programming language. It can be run either with a licensed version of the IDL package or by using the IDL Virtual Machine application that can be obtained from Exelis Visual Information Solutions free of charge as described below. The source code program file can be opened with any text editor to examine the coregistration algorithm. 2.0 Installing and Running the Program 2.1 Extracting the files from the delivery package The read software is packaged as a tar file, coregister_L1B2_L2AS.tar, which can be opened on both Unix and Windows systems. The tar file contains the coregister_L1B2_L2AS.pro source code file, the coregister_L1B2_L2AS.sav executable file, and a bitmap logo file, coregister_airmisr.bmp. On Unix systems, use the following command to extract the files into a directory on your system: tar coregister_L1B2_L2AS.tar On Windows systems, a package such as WinZip for extracting from zipped files will also extract from tar files. Use the package's extract capability to put the three files into the same directory on your system. If you are unable to work with the tar file package, the files may be downloaded separately from the AirMISR tools area on the web page, http://eosweb.larc.nasa.gov/PRODOCS/airmisr/table_airmisr.html Be sure the three files reside in the same directory on your system. 2.2 Using a licensed version of the IDL software package The file coregister_L1B2_L2AS.pro contains multiple procedures so it must be compiled before it can be run. To do this on Unix systems, start IDL by typing "idl" at the Unix command prompt. At the IDL prompt, type ".compile coregister_L1B2_L2AS", then type the procedure name, "coregister_L1B2_L2AS" to start the program. On a PC, or as an alternative on Unix, the IDL development environment can be used. To start IDL this way, type "idlde" at the Unix prompt, select IDL from the Start menu on a PC, or click on the IDL PC desktop icon, if available. Under File, choose "Open" and then select the file coregister_L1B2_L2AS.pro. Then click the compile and run toolbar buttons or, under Run, choose "Compile coregister_L1B2_L2AS.pro" and then under Run, choose "Run coregister_L1B2_L2AS". 2.3 Using the IDL Virtual Machine The IDL Virtual Machine is bundled with IDL and is available from Exelis Visual Information Solutions at http://www.exelisvis.com/Downloads/ProductDownloads.aspx The IDL VM software may be downloaded from this site or ordered from ITT VIS on CD at no cost. The site provides installation instructions. To run an IDL VM application, 1) In Unix At the Unix command prompt, type idl -vm. Click anywhere on the IDL VM splash screen to continue. A dialog box appears for selecting the IDL save file. Navigate to the directory where you placed the coregister_L1B2_L2AS.sav file and select that file. Click the OK button and the coregister_L1B2_L2AS program will start. 2) In Windows, From Windows Explorer, drag the coregister_L1B2_L2AS.sav file onto the IDL Virtual Machine Desktop icon created when the IDL VM was installed. Click on the splash screen, and the coregister_L1B2_L2AS program will start. or Click on the IDL Virtual Machine desktop icon or run the IDL Virtual Machine from the Start menu and click on the splash screen to continue. Use the dialog box that appears to navigate to the directory where you placed the coregister_L1B2_L2AS.sav file, select that file, and click OK to start the coregister_L1B2_L2AS program. 2.4 Program Execution The program begins by displaying a logo screen with an Exit button. Use this button to end execution of the entire program. A dialog box is displayed for selecting an AirMISR L1B2 file. The default directory path is the current directory. If that is not the location of the AirMISR data files, navigate to the desired directory and select a file. If a licensed version of the IDL software is being used, the source code may be modified to specify the initial directory for file selection by changing the value of the PATH keyword in the call to the IDL DIALOG_PICKFILE procedure. After the L1B2 file is selected, a second dialog box is displayed for choosing the associated L2AS file. The default path for this selection is the path where the L1B2 file was found. The PATH keyword for this DIALOG_PICKFILE procedure call may also be modified to specify the desired directory. Be sure to choose the L2AS file from the same AirMISR run as the L1B2 file that was chosen. A quick way to check this is to look at the time stamp portion of the file name in the L1B2 AN camera file for the run. That value will match the time stamp of the corresponding L2AS file. Once these selections are made, three windows will appear on the screen: a window containing an image made from the "Terrain Red" data field in the L1B2 file, a window containing an image made from the "LandDHR Red" data field in the L2AS file, and a text window containing information about the two images. The text information may be cut from the text window and pasted into another application. Each application window may be closed individually using the X button in the upper right window frame, or the entire application may be closed using the Exit button on the initial logo window. 3.0 Additional Assistance If there are questions about installing or using the coregister_L1B2_L2AS software, contact the NASA Langley ASDC User and Data Services office at: Atmospheric Science Data Center NASA Langley Research Center Mail Stop 157D Hampton, VA 23681-2199 USA E-Mail: support-asdc@earthdata.nasa.gov Phone: (757)864-8656 FAX: (757)864-8807 Updated: March 12, 2004 May 19, 2006: Research Systems, Inc. changed to ITT Visual Information Solutions August 3, 2010: changed link for obtaining the IDL Virtual Machine April 20, 2012: changed User Services email address, ITT Vis to Exelis Vis