Sakamoto, T, Shibayama, M, Takada, E, Inoue, A, Morita, K, Takahashi, W, Miura, S, Kimura, A (2010). Detecting Seasonal Changes in Crop Community Structure using Day and Night Digital Images. PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING, 76(6), 713-726.
This study investigates a simple approach using day and night digital images to objectively measure seasonal changes in crop morphology. A paddy field in the Toyama prefecture and a barley field in the Ibaraki prefecture of Japan were observed by two commercially available digital cameras in simple waterproof cases which captured day and night images by shooting at regular intervals using an auto-flash mode. The newly developed NRBINIR (Nighttime Relative Brightness Index in Near Infra Red), based on the nighttime NIR images, had high correlations with plant length until heading (paddy; R-2 = 0.996, barley; R-2 = 0.996), and the total dry weight until 20 days after heading (paddy; R-2 = 0.997). Investigating the temporal pattern of the three indexes (daytime NDVIGR, nighttime NDVIGR, and NRBINIR) coupled with field measurement data, we confirmed that the time-series data derived from inexpensive, specifically modified digital cameras are available for monitoring the seasonal changes in crop growth.