Agriculture Reference
In-Depth Information
elliptical view-area
of each sensor
on the canopy-level
sensed
strip
sensed
strip
sensors
90°
90°
Fig. 9.22
Geometry for oblique viewing of the crop canopy by two sensors on each side of the
tractor. The sensors are positioned on top of the roof of the tractor (From Reusch et al.
2004
,
altered)
one
30
28
26
four (90°)
24
two (180°)
number of sensed directions
and angle between each of them
22
20
view zenith angle = 60°
theta S or theta O = 60°
chlor. conc. = 60
µ
g / cm
2
leaf area index = 3
18
16
0
90
180
270
360
solar azimuth angle in degrees (with respect to the viewing direction)
Fig. 9.23
Effect of solar azimuth angle on the ratio of near-infrared to red reflectance from natural
light. The curves demonstrate the results that can be obtained by averaging the signals from mul-
tiple directions. The reflectance signals are based on the PROSPECT/ SAIL model. For details to
