Overview of This Tutorial - Department of Geosciences
Tutorial: Hyperspectral Signatures and Spectral Resolution
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ENVI Tutorial: Hyperspectral Signatures and Spectral Resolution
View AVIRIS Mean Kaolinite and Alunite Image Spectra
1. From the ENVI main menu bar, select Window → Start New Plot Window. A blank ENVI Plot
Window appears.
2. From the ENVI Plot Window menu bar, select File → Input Data → ASCII. A file selection dialog
appears.
3. Navigate to envidata\c95avsub and select cup95eff.txt. Click Open. An Input ASCII File dialog
appears. Click OK to plot the kaolinite and alunite spectra in the ENVI Plot Window.
4. Compare these spectra to the USGS library spectra (in the Spectral Library Plots window) and to the
spectra from the other sensors.
Open AVIRIS Image
5. From the ENVI main menu bar, select File → Open Image File. A file selection dialog appears.
6. Navigate to envidata\c95avsub and select cup95eff.int. Click Open. A color composite of
bands 183, 193, and 207 automatically loads in a new display group.
7. In the Available Bands List, select the Gray Scale radio button, select Band 193, and click Load
Band.
8. From the Display group menu bar, select Tools → Profiles → Z Profile (Spectrum). A Spectral
Profile plot window appears.
9. From the Display group menu bar, select Tools → Pixel Locator. A Pixel Locator dialog appears.
10. Enter the pixel location (500, 581), which is a Kaolinite feature, and click Apply.
11. Right-click in the Spectral Profile plot window and select Collect Spectra.
12. Enter the following pixel locations and click Apply each time.
Alunite (538, 536)
Buddingtonite (447, 484)
Silica or Opal (525, 505)
13. From the Spectral Profile menu bar, select Edit → Plot Parameters. A Plot Parameters dialog
appears.
14. The X-Axis radio button is selected by default. Enter Range values from 2.0 to 2.5. Click Apply, then
Cancel.
15. Right-click in the Spectral Profile window and select Stack Plots.
16. Compare the AVIRIS image spectra to the library spectra (in the Spectral Library Plots window) and to
spectra from the other sensors.
17. See Draw Conclusions on page 19, and answer some of the questions pertaining to AVIRIS data.