Use the Spectral Library Viewer to view data from Metadata Rich Spectral Library (MRSL) files that were created in the THOR Spectral Library Builder. MRSL files provide several advantages over ENVI’s standard spectral libraries such as the ability to store signatures with variable spectral ranges and band spacings, as well as unlimited metadata for each signature. The THOR Spectral Library Viewer is essentially identical to ENVI's Spectral Library Viewer, except that it also displays metadata associated with the selected signature.

  1. From the Toolbox, select THOR > THOR Spectral Library Viewer. The Select Spectral Library File dialog appears.
  2. Open a spectral library file. If you select a standard ENVI spectral library (.sli), ENVI's Spectral Library Viewer will launch. If you select an MRSL library, THOR's Spectral Library Viewer will launch.
  3. The left side of the Spectral Library Viewer dialog lists all the signatures within the selected library. The right side of the viewer uses tabs to display metadata for the selected signature (if any) and query parameters.

  4. To plot a signature, click on the desired signature in the list. If a plot window is not already open, a new one will be created and the signature added to it. Otherwise, the signature will be plotted in the open window. The metadata for the selected signature (if any) will appear in the Metadata tab. Clicking on a metadata cell displays its contents in the text box below the table, making it easier to read long fields.
  5. In some cases, you may want to compare library signatures to image signatures that have different wavelength units or y-axis scaling. Enter the desired values in the X Scale and/or Y Scale boxes. The next time you select a signature from the list, these scale factors will be applied to the signature. You can then drag these signatures into a plot window displaying an image signature for direct comparison.
  6. It is possible to list only those signatures in the library that match certain metadata criteria. Click the Query Parameters tab to show the metadata query parameters.