Natural color (NC) and color infrared (CIR) video systems were used to acquire oblique and near-nadir imagery of citrus grove areas that were damaged by cold temperatures during the nights of February 25 and 26, 1989. Two flights were made 10 days apart from 9:30 am to 12:00 noon each day at 100 m and 300 m altitudes. The video cameras adjusted to the changing light intensity caused by cloud interference and turbulent weather and produced acceptable images for the detection of freeze damage and delineation of damaged areas. The contrast between green and brown video images was less distinctive than the contrast between cyan and magenta of the CIR video. Both NC and CIR video cameras captured images of damaged citrus trees, but it was not possible to measure the areas with an image analysis system because images were oblique and were acquired in different overflights of the damaged areas. The major benefits derived from videography were instant acquisition and viewing of images, rapidly locating damaged areas, and determining that all sites were imaged.
Carlos H. Blazquez,
"Detection of citrus freeze damage with natural color and color IR video systems", Proc. SPIE 1467, Thermosense XIII, (1 March 1991); doi: 10.1117/12.46451; https://doi.org/10.1117/12.46451