Work

Estimation of feed rapeseed biomass based on multi-angle oblique imaging technique of unmanned aerial vehicle

Year: 2021

Type: article

Abstract: To obtain above-ground biomass information quickly and accurately facilitating crop growth monitoring and yield prediction, this study was to evaluate a new method to extract the biomass of feed rapeseed based on UAV with visible-light cameras. The experiment was conducted at the rapeseed experimental base of Huazhong Agricultural University in 2018. To estimate above-ground biomass of rapeseed, a UAV (unmanned aerial vehicle) platform equipped with a five-camera oblique photography system was used to simultaneously obtain images of rapeseed during final flowering period from multiple angles. Three flight altitudes (40, 60, and 80 m) and three seeding densities (3.00×105, 5.25×105, and 7.50×105 plant hm-2) were carried out to assess biomass predictions in a single-camera vertical imaging pattern. Firstly, the rapeseed canopy coverage and plant height information from the image of the UAV were extracted. Secondly, the volume model of rapeseed was obtained by the addition of plant height on the covering area. Finally, a linear regression model was established based on volume model and measured biomass to predict the dry weight of rapeseed. The results were as follows: (1) With the decrease of the flight height of the UAV of the three flight altitudes, the accuracy of biomass prediction was on the rise, and when the flight height was 40 meters, the accuracy of rapeseed biomass estimation was the best (calibration set: r = 0.792, RMSE = 125.0 g m -2, RE = 13.2%; validation set: r = 0.752, RMSE = 139.1 g m -2, RE = 15.3%). (2) When the planting density of rapeseed was higher, the actual biomass was smaller, and the prediction of biomass had a better result by volume model. (3) There was no significant difference in the accuracy of rapeseed biomass estimation between multi-angle imaging and single-camera vertical imaging, both of which had the best results at the flight height of 40 meters with correlation coefficients rof 0.772 and 0.742, respectively. This study indicated that it was feasible to obtain images for extracting rapeseed biomass by a UAV, which could provide the reference for efficient and accurate phenotypic information of field crops.

Source: ACTA AGRONOMICA SINICA

DOI: 10.3724/sp.j.1006.2021.04211