. Istanbul 2004 
s resides in the 
VI reaches à 
ceeds 2, while 
vithout a clear 
«plains, in part, 
>nness measure 
fect, we plotted 
ectance (Figure 
variations. The 
 reflectance is 
ural descriptors 
gure I: NDVI 
ed 0.35 to 0.40 
/12 appear to be 
crease. Indeed, 
nge when NIR 
beans and peas. 
ted by the red 
VI approached 
further change, 
10. Conversely, 
e substantially, 
ontrast, MTVD 
NIR reflectance 
imic in the red 
ed by indices 
nce variability. 
effect, NDVI 
ly in the case of 
or the dynamic 
NIR reflectance 
0.60 0.70 
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B7. Istanbul 2004 
  
  
  
  
  
  
  
  
  
  
  
PE ge ° 
ed DO 
090 B NDVI ré E n 
N i @ ab, AA 
: oD A 
0 - ^ MSAVI — — AM qui Ee a iod 
0.80 S e 
$ ® MTVI2 d e^ 
S 9 $5 A 
3 0.70 zn E 
A n a @ A 
= 9 
£ 0.60 go m e. ^ 
© a A 
à 
N a 
= 0.50 5 a 
2 ! ® 
a é 
8 040 
3 e 
= 030 
© 
o 
X 
0.20 
0.10 —_—--" 
WP o 7 "n 
lh gu, 8 LI des u | 
0.00 — - + t terit —: 
0.10 0.20 0.30 0.40 0.50 0.60 0.70 
n NIR Reflectance 
0.90 — 
0.80 
Bne 
7 0.70 Red 
E D NDVI 
= : 
- 0.60 A MSAVI 
3 ® MTVI2 
$ 0.50 
un 
> 
2 040 
s 
5 $ 
= 030 
a 
3 
c 020 
| 
0.10 = = rome pre 
Pe Aa mn | 
0.00 | 1 
0.10 0.20 0.30 0.40 0.50 0.60 0.70 
NIR Reflectance 
Figure 1. Sensitivity of red reflectance, NDVI, MSAVI2 and 
MTVI2 to changes in the NIR reflectance of crop canopies 
(Corn (a), Beans (b), and Peas (c)). Data are from the campaign 
of 2003. 
3.2 Relationships Indices - LAI 
The relationships between vegetation indices and LAI are not 
unique; they exhibit a considerable scatter caused by 
chlorophyll content variation and/or the influence of other 
canopy characteristics. In fact, the indices are designed to 
measure vegetation greenness in which chlorophyll content 
plays a major role as well as the amount of green leaves. 
Our result for the four years of measurements revealed that 
equations relating indices to crop canopy reflectance is crop 
type-dependent. This is due to the range of LAI values, which 
was found to be wide for soybean, beans and peas, intermediate 
for corn, but intermediate to low for wheat. In this section, we 
present the relationships between NDVI, MSAVI, and MTVI2 
and measured LAI for the only case of pea canopies (Figure 2). 
111 
7.00 — E E as cac RENE eM 
% 
6.00 
4 
8 
un 
2 
y 
4.00: 
LAI 
3.00 
2.00 
  
  
  
0.00 
0.00 0.20 0.40 0.60 0.80 1.00 
  
  
  
  
  
6.00 
5.00 
LAI 
1.00 
  
  
  
0.00 — 
0.00 0.20 0.40 0.60 0.80 1.00 
b MSAVI2 . 
  
  
  
  
740 q——————————————————7 
6.00 
5.00 
4.00 
LAI 
3.00 
2.00 
1.00 
  
  
  
0.00 : 
0.00 0.20 0.40 0.60 0.80 1.00 
c MTVI2 
  
  
  
  
Figure 2. Relationships between spectral indices and measured 
LAI for pea canopies (2000-2003): NDVI (a), MSAVD (b), and 
MTVI2 (c).