Development of a multi-band sensor for crop temperature measurement

A system combining a miniature long wavelength infrared (LWIR) camera with a visible, or RGB, camera was developed to capture a field of view and derive a plant-specific temperature measurement. The electronic and software development of the instrument, including calibration, field operation, and post-processing of data, are described. Calibration of the LWIR camera was accurate to 0.65 degrees C when relating pixel output to a thermal measurement, allowing it to act as a thermal camera. A processing algorithm was developed to identify plants within a visible camera image using a binary mask to identify crop/non-crop components within the field of view. The mask was then used to obtain a crop-only region of interest from the thermal image, over which data were integrated to create a temperature measurement. The instrument was tested against an infrared thermometer on soybean plots during September and October 2016. It was capable of removing shaded areas and soil from thermal images to produce temperature measurements more representative of the crop canopy.