Figure 6. Expert system analysis of calcite lab 
spectrum (Figures 2 and 3, From Kruse et 
al., 1990a). 
6A. FEATURE ANALYSIS: 
BAND 
ORDER 
WAVE(um) 
DEPTH 
FWHM 
ASYM 
1 
1/1 
2.340 
0.3001 
0.0980 
0.3047 
2 
1/1 
1.997 
0.0788 
0.0490 
0.5154 
3 
1/1 
1.870 
0.0603 
0.0490 
0.6033 
4 
1/1 
2.164 
0.0452 
0.0392 
0.1947 
6B. EXPERT SYSTEM BROAD CLASSIFICATION: 
There are features from: vegetation 
carbonates 
clays 
micas and illites 
calcite 
6C. BINARY 
ENCODING MATCHES (percentage): 
Buddingtonite 
85.24 
Kaolinite 
80.00 
Montm 
82.86 
Pyrophyllite 
83.33 
Illite 
35.71 
Muscovite 
56.19 
Alunite 
74.76 
Gypsum 
65.71 
Epidote 
53.81 
Chlorite 
40.95 
Calcite 
100.00 
Dolomite 
86.19 
Actinolite 
52.38 
Tremolite 
84.29 
Jarosite 
58.10 
Hematite 
53.81 
Goethite 
56.67 
Green Vegetation 
58.10 
Dry Grass 
73.33 
6D. CALCITE FINAL RESULTS - WEIGHTED DECISION: 
According to the expert system and the binary encoding 
performed on the spectrum, the probability of the presence of: 
perpendicular to the the aircraft direction. The 
second dimension of the images is provided by the 
forward motion of the aircraft, which moves the 
ground field of view along the terrain. 
Two areas were initially selected for analysis with the 
expert system. To simplify the testing, these were 
both geologic sites in semi-arid areas of well exposed 
mineralogy. Future efforts will look at more difficult 
test sites. The feature extraction procedures and the 
expert system were successfully used to analyze 
individual imaging spectrometer spectra for the two 
sites. The expert system successfully identified the 
minerals kaolinite, alunite, and buddingtonite at one 
site using 63 channel imaging spectrometer data 
(Kruse et ah, 1990b) and the minerals hematite, 
goethite, sericite (fine grained muscovite), calcite and 
dolomite at another site using the 224 channel 
AVIRIS data (Kruse, 1990; Kruse et ah, 1990a). 
The AVIRIS data were obtained during May 1989 
with signal-to-noise ratios of approximately 50/1 at 
0.70 pm and 20/1 at 2.20 pm. They were calibrated to 
reflectance using ground targets and the empirical 
line method (Kruse et al., 1990b). Two wavelength 
ranges of the AVIRIS data were used to identify and 
map the distribution of alteration minerals. The 
short-wave infrared data from 2.0 to 2.5 micrometers 
were used to identify and map the distribution of 
sericite, calcite, and dolomite. The visible and near- 
infrared (0.41-1.2 pm) portions of the spectrum were 
used for identification and mapping of iron oxide 
minerals. 
Calcite is nearly certain 
Dolomite is medium 
Buddingtonite is medium 
Muscovite is medium 
6E. JUSTIFICATION - CALCITE: 
The binary match to calcite is 100.00 % so 
the binary match is rated very high 
The carbonate feature between 2.30 and 2.35 pm is present 
The calcite feature at 2.34 pm is present 
The overall expert guess for the probability of 
calcite is Nearly Certain 
6F. JUSTIFICATION - DOLOMITE: 
The binary match to dolomite is 86.19 % so 
the binary match is rated high 
The carbonate feature between 2.30 and 2.35 pm is present 
The dolomite feature at 2.32 pm is not present 
The overall expert guess for the probability of dolomite is 
Medium 
AVIRIS IMAGE ANALYSIS 
AVIRIS is the first of a second generation of imaging 
spectrometers measuring near-laboratory quality 
spectra in 224 10 nm-wide channels in the spectral 
range 0.41 to 2.45 pm (Porter and Enmark, 1987). The 
AVIRIS is flown aboard the NASA ER-2 aircraft at an 
altitude of 20 km, with an instantaneous field of 
view of 20 m and a swath width of about 10 km. It 
utilizes four linear arrays and four individual 
spectrometers to collect data simultaneously for the 
224 bands in a scanned 614 pixel-wide swath 
Figure 7 shows individual spectra extracted from 
AVIRIS data for known occurrences of calcite, and 
dolomite and the expert system classification and 
justification for the calcite spectrum. Comparison of 
the shapes and positions of the absorption features 
with laboratory spectra makes positive identification 
of the minerals possible. The 1989 AVIRIS data not 
only allow identification of the carbonate-group- 
minerals, but permit identification of the individual 
species (calcite and dolomite) based upon a 20 nm (2 
channel) difference between the position of the main 
absorption feature (2.34 vs 2.32 pm). The feature 
WAVELENGTH (Micrometers) 
Figure 7. Spectra extracted from AVIRIS data for 
calcite and dolomite (from Kruse et al., 
1990a).