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Effects of distance to target, time of the day, wetness of the leaves, and sensor position on active sensor readings. Fernando Solari, Paul Hodgen, John Shanahan, and Jim Schepers. Objectives. To determine how Sensors distance to the target Time of the day Wetness of the leaves
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Effects of distance to target, time of the day, wetness of the leaves, and sensor position on active sensor readings Fernando Solari, Paul Hodgen, John Shanahan, and Jim Schepers
Objectives To determine how • Sensors distance to the target • Time of the day • Wetness of the leaves • Shifts from on row position Affects sensor readings outputs
GDO sensor
Distance to target 2% cv2% 4%
VI=(ρ-1 VIS- ρ-1 IR) * ρIR 1% 3% 6% 1%
Distance to target 36in+-14in CV 7% 35+-7 CV 4%
Distance to targetConclusions • Crop Circle: 40 to 100 cm lowest CV for NDVI and Gitelson VI • GreenSeeker: 70-105 cm lower CV than 55-125cm
Timeof the day effect study 8:00 17:00 12:00
Table 1: NDVI values Different letters are significant differences within column (sensor and stage)
Time of the day effect studyConclusions • Time of the day can affect sensor readings • (Growth?, Wind?, Power supply,?)
Across rows 6 in=15cm 91 cm ROW ROW
On the row studyConclusion • The principal effect of to be off the row is underestimation. • The effect is much more important at early stages.
Wetness of the leaves a a a
Conclusions • Distance: • GreenSeeeker: 80-110cm cm to target • Crop Circle: 40-100 cm to target • Time of the day • Time of the day can affect sensor readings (Growth?, Wind?, Power supply,?) • Position • Important to be on row (If not, underestimation) • Watering • Does not affect