Overview of This Tutorial - Department of Geosciences

Tutorial: Hyperspectral Signatures and Spectral Resolution

ENVI Tutorial: Hyperspectral Signatures and Spectral Resolution

Draw Conclusions

1. From the library spectra, what is the minimum spacing of absorption features in the 2.0 - 2.5 µm

range?

2. The TM data dramatically undersample the 2.0 - 2.5 µm range, as only TM band 7 is available. What

evidence do you see for absorption features in this range? What differences are apparent in the TM

spectra of minerals with absorption features in this range?

3. The GEOSCAN data also undersample the 2.0 - 2.5 µm range, however, the bands are strategically

placed. What differences do you see between the GEOSCAN spectra for the different minerals? Could

some of the bands have been placed differently to provide better mapping of specific minerals?

4. The GER63 data provide improved spectral resolution over the GEOSCAN data, and you can observe

individual features. The advertised spectral resolution of the GER63 between 2.0 - 2.5 µm is 17.5 nm.

Examine the GER63 kaolinite spectrum and defend or refute this specification. Do the more closely

spaced spectral bands of the GER63 sensor provide a significant advantage over the GEOSCAN data in

mapping and identifying these reference minerals?

5. What are the main differences between mineral spectra at Cuprite caused by the change from 10 nm

spectral resolution (AVIRIS) to 17 nm spectral resolution (HyMap)?

6. The AVIRIS data provide the best spectral resolution of the sensors examined here. How do the

AVIRIS and laboratory spectra compare? What are the major similarities and differences? What factors

affect the comparison of the two data types?

7. Examine all of the images and spectra. What role does spatial resolution play in the comparison?

8. Based on the library spectra, provide sensor spectral and spatial resolution design specifications as

well as recommendations on placement of spectral bands for mineral mapping. Examine the trade-offs

between continuous high-spectral resolution bands and strategically placed, lower-resolution bands.