Impact of UAV Time-of-Flight on Rice Nitrogen Uptake Models

This work examines the impact of image acquisition time on rice paddy remote sensing data in Yanco, NSW, Australia. The normalized difference red edge (NDRE) is an important vegetation index for rice paddy N status. Models of midseason N uptake were extracted using physical samples and NDRE data taken at multiple times of day from a UAV with multi-spectral camera. The best prediction error was 15.8 kg/ha. With a model extracted at 13:00 on 1 January, model predictions from 27 December to 11 January, at image times from 11:00 to 16:00, N uptake prediction errors were less than 28.5 kg/ha. Predictions from images acquired at times very different from the one used to extract the model are more erroneous.