Submitted to: ASABE Annual International Meeting
Publication Type: Proceedings
Publication Acceptance Date: 10/20/2006
Publication Date: 4/20/2007
Citation: Thomson, S.J., Sullivan, D.G. 2007. Crop Status Monitoring using Multispectral and Thermal Imaging systems for Accessible Aerial Platforms. Technical Paper No. 061179. ASABE, St. Joseph, MI. Interpretive Summary: To obtain remote sensing data frequently for crop management, easily scheduled and convenient remote sensing platforms should be utilized. In areas of the U.S. that agricultural aircraft are used for crop spraying, these aircraft are ideal as remote sensing platforms. However, there are many areas of the country that are not served by agricultural aircraft. In these cases, Unmanned Aerial Vehicles (UAVs) can provide frequent remote sensing data using small or miniaturized cameras. Two studies were conducted to evaluate thermal imaging systems on both aircraft and UAV platforms. An Electrophysics thermal imaging camera was used in an Air Tractor 402B aircraft to observe canopy temperature trends as the soil dried. Soil water sensors monitored soil water potential simultaneously and weather was monitored using an in-field weather tracker as the airplane flew over the field. Trends in canopy temperature could be associated with crop water stress to some extent, but results were influenced by aircraft altitude and differences in incoming solar radiation. A field application was also conducted to determine changes in peanut response to four tillage regimes with the assistance of a handheld CropScan multispectral radiometer, Fluke Ti30 thermal imager, and NASA ImageAire UAV with a small Raytheon thermal imaging camera. Using the UAV, thermal infrared (TIR) data were sensitive to a 15% change in canopy temperature, and the UAV/TIR camera showed good potential for detecting changes in crop response to tillage treatment.
Technical Abstract: Agricultural aircraft and unmanned aerial systems (UAS) are easily scheduled and accessible remote sensing platforms. Canopy temperature data were taken with an Electrophysics PV-320T thermal imaging camera mounted in agricultural aircraft. Weather data and soil water potential were monitored and thermal images were analyzed for canopy temperature trends accounting for rainfall, irrigation, aircraft altitude, and weather. Canopy temperature responses tracked crop wetting and drying cycles fairly well, but temperature represented at the camera was influenced by the altitude of acquisition. A field application was conducted to determine changes in peanut response to four tillage regimes with the assistance of both a handheld CropScan multispectral radiometer and Fluke Ti30 thermal imager. Ground truth data included digital images for classification of surface cover and canopy closure, soil water content (0-20cm), bulk density (0-8, 8-15, 15-23 cm), and peanut yield. Preliminary analyses indicate that thermal infrared data were more sensitive to changes in the canopy response to soil conditions compared to vegetation indices derived using visible and near-infrared reflectance. Using a NASA ImageAire unmanned aerial vehicle (UAV), thermal infrared (TIR) data were sensitive to a 15% change in canopy temperature