Automatic instance segmentation of orchard canopy in unmanned aerial vehicle imagery using deep learning

Abstract

The widespread use of unmanned aerial vehicles (UAV) is significant for the effective management of orchards in the context of precision agriculture. To reduce the traditional mode of continuous spraying, variable target spraying machines require detailed information about tree canopy. Although deep learning methods have been widely used in the fields of identifying individual trees, there are still phenomena of branches extending and shadows preventing segmenting edges of tree canopy precisely. Hence, a methodology (MPAPR R-CNN) for the high-precision segment method of apple trees in high-density cultivation orchards by low-altitude visible light images captured is proposed. Mask R-CNN with a path augmentation feature pyramid network (PAFPN) and PointRend algorithm was used as the base segmentation algorithm to output the precise boundaries of the apple tree canopy, which addresses the over- and under-sampling issues encountered in the pixel labeling tasks. The proposed method was tested on another miniature map of the orchard. The average precision (AP) was selected to evaluate the metric of the proposed model. The results showed that with the help of training with the PAFPN and PointRend backbone head that AP_seg and AP_box score improved by 8.96% and 8.37%, respectively. It can be concluded that our algorithm could better capture features of the canopy edges, it could improve the accuracy of the edges of canopy segmentation results.

An Open-Source Package for Thermal and Multispectral Image Analysis for Plants in Glasshouse

“…The image processing pipeline was designed specifically for controlled environment conditions, since, for field conditions, image acquisition has moved from handheld cameras to sensors mounted on unmanned aerial vehicles. Other segmentation methods such as Mask R-CNN [ 80 ] and semantic segmentation [ 81 ] can be implemented if the setup is to be used in field conditions. Additionally, measures can be applied to correct temperature that may be affected by the thermal emissions and reflections from surrounding objects [ 33 ].…”