Overview of This Tutorial - Department of Geosciences

Tutorial: Hyperspectral Signatures and Spectral Resolution
1. From the ENVI main menu bar, select Spectral → Spectral Libraries → Spectral Library Viewer.
A Spectral Library Input File dialog appears.
2. Click Open and select Spectral Library. A file selection dialog appears.
3. Navigate to envidata\cup_comp and select usgs_em.sli. These spectra represent USGS
laboratory measurements for kaolinite, alunite, buddingtonite, and opal, in Cuprite, measured with a
Beckman spectrometer. Click Open.
4. Select usgs_em.sli in the Spectral Library Input File dialog, and click OK. The Spectral Library
Viewer dialog appears.
5. In the Spectral Library Viewer dialog, select each mineral. The spectra appear in a Spectral Library
Plots window.
6. Examine the detail in the spectral plots, particularly the absorption feature positions, depths, and
shapes near 2.2 - 2.4 µm. For better comparison, use the middle mouse button to draw a box in the
plot window from 2.0 to 2.5 µm.
Following is an annotated plot of laboratory spectra for kaolinite, alunite, and buddingtonite, showing
the absorption features of interest:
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ENVI Tutorial: Hyperspectral Signatures and Spectral Resolution