Master of Science / Department of Biological & Agricultural Engineering / Ajay Sharda / Precise water application conserves resources, reduces costs, and optimizes plant
performance and quality. Existing irrigation scheduling utilizes single, localized measurements
that do not account for spatial crop water need; but, quick, single-point sensors are impractical for
measuring discrete variations across large coverage areas. Thermography is an alternate approach
for measuring spatial temperatures to quantify crop health. However, agricultural studies using
thermography are limited due to previous camera expense, unfamiliar use and calibration, software
for image acquisition and high-throughput processing specifically designed for thermal imagery
mapping and monitoring spatial crop water need. Recent advancements in thermal detectors and
sensing platforms have allowed uncooled thermal infrared (TIR) cameras to become suited for
crop sensing.
Therefore, a small, lightweight thermal infrared imaging system (TIRIS) was developed
capable of radiometric temperature measurements. One-time (OT) and real-time (RT) radiometric
calibrations methods were developed and validated for repeatable, temperature measurements
while compensating for strict environmental conditions within a climate chamber. The Tamarisk®
320 and 640 analog output yielded a measurement accuracy of ±0.82°C or 0.62ºC with OT and RT
radiometric calibration, respectively. The Tamarisk® 320 digital output yielded a measurement
accuracy of ±0.43 or 0.29ºC with OT and RT radiometric calibration, respectively. Similarly, the
FLIR® Tau 2 analog output yielded a measurement accuracy of ±0.87 or 0.63ºC with OT and RT
radiometric calibration, respectively.
A TIRIS was then built for high-throughput image capture, correction, and processing and
RT environmental compensation for monitoring crop water stress within a greenhouse and
temperature mapping aboard a small unmanned aerial systems (sUAS). The greenhouse TIRIS was
evaluated by extracting plant temperatures for monitoring full-season crop water stress index
(CWSI) measurements. Canopy temperatures demonstrated that CWSI explained 82% of the soil
moisture variation. Similarly, validation aboard a sUAS provided radiometric thermal maps with
a ±1.38°C (α=0.05) measurement accuracy. Due to the TIR cameras’ performance aboard sUAS
and greenhouse platforms, a TIRIS provides unparalleled spatial coverage and measurement
accuracy capable of monitoring subtle crop stress indicators. Further studies need to be conducted
to produce spatial crop water stress maps at scales necessary for variable rate irrigation systems.
| Identifer | oai:union.ndltd.org:KSU/oai:krex.k-state.edu:2097/35241 |
| Date | January 1900 |
| Creators | Mangus, Devin |
| Publisher | Kansas State University |
| Source Sets | K-State Research Exchange |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
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