The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B7. Beijing 2008 
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Spectral variables 
Characteristic of the plant related with the 
variable/index 
Definition 
Described by 
A-1D, B-1D, C-1D, D-1D, E-1D, 
F-1D,G-1D, H-1D, I-1D.J-1D, 
maximum 1st derivative spectra 
Pigments absorption in visible region and 
water, cellulose, starch and lignin absorption 
inNIRand SWIR. 
Maximum 1st derivative spectra of 10 'slopes' : 
blue edge , yellow edge and red edge and other 
7 'slopesi in NIR and SWIR regions 
Gong et al., 2002 
Pu et al., 2004 
A-WP, B-WP, C-WP, D-WP, E- 
WP, F-WP, G-WP, H-WP, I- 
WP.J-WP, spectral position 
variables corresponding "IDs" 
Pigments absorption in visible region and 
water, cellulose, starch and lignin absorption 
in NIR and SWIR. 
Corresponding spectral positions of "IDs" of 10 
'slopes' : blue edge , yellow edge and red edge 
and other 7 'slopesi in NIR and SWIR regions 
Gong et al., 2002 
Pu et al., 2004 
R550 
Chlorophyll content 
Reflectance at 550 nm 
Thomas and Gausman, 1977 
R680 
Chlorophyll content 
Reflectance at 680 nm 
Thomas and Gausman, 1977 
Wl, Water Index 
Water status 
R900/R970 
Periuelas et al., 1997 
NDVI, Normalized Difference 
Vegetation Index 
Photosynthetic area; cell structure multi- 
reflected spectra 
(Rnir-R r )/(Rnir+Rr) 
Rouse et al., 1973 
SR, Simple Ratio 
Same as NDVI 
Rnir/Rr 
Jordan, 1969 
PRI, Photochemical Reflectance 
Index 
Water stress 
( R531^570 V ( R531 + R57O ) 
Thenot et al., 2002 
SIPI, Structural Independent 
Pigment Index 
Carotenoids: chlorophyll a ratio 
(R 4 45-R 8 oo)/(R680‘R80o) 
Periuelas and Filella, 1998 
NPCI, Normalized total Pigment 
to Chlorophyll Index 
Senescence 
( R680-R430)/(R680 + R430) 
Periuelas et al., 1994 
NPQI, Normalized 
Phaeophytinization Index 
Senescence 
(R415-R435)/(R435+R4 35 ) 
Barnes et al., 1992 
Periuelas et al., 1995 
LCI, Leaf Chlorophyll Index 
Chlorophyll content 
(R850“R71oV(R850 + R68o) 
Datt, 1999 
NDWI, ND Water Index 
Water status 
(R860-Rl240y(R860 + Rl240) 
Datt et al., 2003 
Gao, 1996 
DSWI, Disease water stress 
Water status 
(R 8 02+R547)/(Rl657 + R682) 
Galvâo et al., 2005 
RATI0 975 3-band ratio at 975 
nm 
Water status 
2*R960-990/( R920-940+ Rl090-1110) 
Pu et al., 2003 
RATI0 120 o 3-band ratio at 1200 
nm 
Water status 
2*Rl180-1220/( Rl090-1110+ R-1265-1285) 
Pu et al., 2003 
WP-975: wavelength position at 
975 nm 
Water absorption feature at 975 nm 
See reference for the defiinition of wavelength 
position at 975 nm 
Pu et al., 2003 
DEP-975 absorption depth at 
975 nm 
Water absorption feature at 975 nm 
See reference for the defiinition of absorption 
depth at 975 nm 
Pu et al., 2003 
WID-975 absorption width at 
975 nm 
Water absorption feature at 975 nm 
See reference for the defiinition of absorption 
width at 975 nm 
Pu et al., 2003 
AREA-975 absorption area at 
975 nm 
Water absorption feature at 975 nm 
See reference for the defiinition of absorption 
area at 975 nm 
Pu et al., 2003 
WP-1200: wavelength position 
at 1200 nm 
Water absorption feature at 1200 nm 
See reference for the defiinition of wavelength 
position at 1200 nm 
Pu et al., 2003 
DEP-1200 absorption depth at 
1200 nm 
Water absorption feature at 1200 nm 
See reference for the defiinition of absorption 
depth at 1200 nm 
Pu et al., 2003 
WID-1200 absorption width at 
12Q0 nm 
Water absorption feature at 1200 nm 
See reference for the defiinition of absorption 
width at 1200 nm 
Pu et al., 2003 
AREA-1200 absorption area at 
1200 nm 
Water absorption feature at 1200 nm 
See reference for the defiinition of absorption 
area at 1200 nm 
Pu et al., 2003 
WP-1750: wavelength position 
at 1750 nm 
Water absorption feature at 1750 nm 
See reference for the defiinition of wavelength 
position at 1750 nm 
Tian et al., 2001 
Pu et al., 2003 
DEP-1750 absorption depth at 
1750 nm 
Water absorption feature at 1750 nm 
See reference for the defiinition of absorption 
depth at 1750 nm 
Tian et al., 2001 
Pu et al., 2003 
WID-1750 absorption width at 
1750 nm 
Water absorption feature at 1750 nm 
See reference for the defiinition of absorption 
width at 1750 nm 
Tian et al., 2001 
Pu et al., 2003 
AREA-1750 absorption area at 
1750 nm 
Water absorption feature at 1750 nm 
See reference for the defiinition of absorption 
area at 1750 nm 
Tian et al., 2001 
Pu et al., 2003 
Table 2. Summary of 46 spectral variables extracted from the in situ hyperspectral measurements for this analysis. 
second group of spectral variables relates the characteristics 
and pigment status (primarily chlorophyll) of leaves among the 
difference species and its spectral variables consist of C-1D, 
A-ID, B-1D, R550, A-WP, SIPI, NPQI, LCI, B-WP, SR, J-1D, 
NPCI C-WP, R680, H-1D, and F-1D. 
4.2 Species Recognition 
To train and test the three-layer ANN structure for classifying 
the 11 species (including five oak species), the input of 30 
selected spectral variables was first normalized to the range of 
[0, 1]. The output layer had 11 nodes corresponding 11 species 
(or 5 nodes for 5 oak species). To find a better ANN structure, 
various combinations of learning rate (r|), momentum 
coefficient (a) and number of nodes in a hidden layer (hi) were 
tested using the first training/test data set (Table 1). In 
considering relatively small variation of OAA values with all 
testing nodes (hi: 10 - 40) and convenience to design the ANN 
networks, for identifying the 11 species, all ANNs use hi = 25 
or 30, r| = 0.8 or 0.7, and a = 0.1 Or 0.2 while for identifying 5 
oak species, all ANNs use hi = 16 or 20, r\ = 0.8 or 0.7, a = 
0.1 or 0.2. 
For classifying both 11 species and a subset of 5 oak species, 
the first row of Table 3 shows classification results calculated 
from three sets of test samples by ANN. From the table, we can 
see that the classification accuracies (OAA) of averaging three