Agriculture Reference
In-Depth Information
determination (r
2
)
Formulas for wavelengths R
(number added is wavel. λ in nm)
Coeffic. of
determination (r
2
)
Definition
Standard indices (commonly used)
Near-infrared reflect.
R 850
0.16
R
R
780
670
Ratio of near-infrared to red
0.63
R
R
780
550
Ratio of near-infrared to green
0.72
R
780
−
+
R
670
Normalized difference vegetat.
index (NDVI)
0.55
R
780
R
670
15 780
.(
R
−
R
670
)
Soil adjusted vegetation index
(SAVI)
0.51
R
780
+
R
670 05
+
.
(
R
670
+
R
780
) /
2
−
R
700
Red edge inflect. point, approx.
formula (REIP)
700 40
+
0.73
R
740
−
R
700
New indices with wavelengths exclusively from the red edge range
R
R
780
740
Red edge ratio index
0.82
R
R
740
780
Inverse red edge ratio index
0.81
R
780
−
+
R
740
Normalized difference red edge
indices
0.82
R
780
R
740
R
750
−
+
R
740
0.82
R
750
R
740
The results are based on winter-oilseed rape, vertical viewing and natural illumination (Arranged
from data by Müller et al.
2008
)
60
seed-densities:
90 seeds per m
2
160 seeds per m
2
330 seeds per m
2
50
40
30
20
y = 1.041x + 0.040
r
2
= 0.958
10
0
0
10
20
30
40
50
in laboratory analysed uptake of nitrogen in kg N per ha
Fig. 9.28
Accuracy of nitrogen sensing by a red edge ratio index (R760/R730) versus analysing
of samples chemically in a laboratory with winter-wheat in Northwest Germany. The sensing was
done from the roof of a tractor in an oblique direction with artificial light and at a growth stage of
EC or BBCH 31. The field was fertilized with different rates of nitrogen at a growth stage of EC or
BBCH 20 (From Jasper et al.
2009
)
