Spectral Library Viewer

Use the Spectral Library Viewer to visualize data from ENVI standard spectral library (SLI) files and Analytical Spectral Devices (ASD) spectrometers output.

ENVI includes several groups of laboratory spectra from the NASA Jet Propulsion Laboratory (JPL), Johns Hopkins University (JHU), and the U.S. Geological Survey (USGS). These spectra are located in the \resource\speclib directory of the ENVI installation path. They are organized by subdirectories according to the different data providers. See Spectral Libraries for references.

To open and plot a spectral library:

1. Use one of the following:

   • Select Display > Spectral Library Viewer from the menu bar.
   • Select File > Open from the menu bar, then open a spectral library file.
   • In the Data Manager, click the Open button, then open a spectral library file.

   The Spectral Library Viewer appears. By default, the left panel of the viewer lists all the spectral libraries that are in the installed \speclib directory. When you plot a spectral library, the center panel will contain the plot, and the right panel will contain the plot key and plot properties. The right panel is hidden when the Spectral Library Viewer opens; click the Show arrow to open it.

2. Click the Open Spectral Library button, then select an MRSL, ASD, or SLI file.
3. Use the Search field to search for a particular signature.
4. Click a spectrum in the Spectral Library Viewer tree to plot it. Click additional signatures in the tree to overplot them in the viewer. You can also import data from an ASCII file or spectral library using the Import drop-down list in the Spectral Library Viewer. See Import Plot Data for details.

The following buttons at the top of the left panel control the Spectral Library Viewer tree:

• Click the Open Spectral Library button to open a library that is not already open in the tree.
• Click the Close Spectral Library button to remove a library from the tree.
• Click the Close All Spectral Library button to remove all libraries from the tree.
• Use the Expand All and Collapse All buttons to expand or collapse the tree display.

Here are links to additional details:

• You can import data from an ASCII file or spectral library using the Import drop-down list in the profile window.

• The plot window controls and plot properties change the display and appearance of the plot.

• You can export data using the Export drop-down list in the profile window.

• The Material Identification Tool can be used with a profile or plot to compare an unknown spectrum with a spectral library of known spectra and rank the similarity between the two using a variety of common spectral similarity algorithms.

Drag and Drop Curves to Other Profiles or Plots

You can drag and drop curves between any profile or ENVI Plot window and the Spectral Library Viewer for analysis:

1. Open any profile window or ENVI Plot window with data.
2. Click the arrow on the right side of the profile window and the Spectral Library Viewer to expand the panels and show the plot key.
3. In the Spectral Library Viewer, select a curve. You can also use Ctrl+click to multi select.
4. Drag the selected items to the profile window. The curves appear in the corresponding plot. If the incoming curve or the receiving plot (or both) are missing wavelength units and/or y-scale factor information, the Scale Incoming Curve Data dialog appears.

See Also

Spectral Libraries, Spectral Library References