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article · Frontiers in Plant Science

Maize plant detection using UAV-based RGB imaging and YOLOv5

202437 citationsOpen accessUniversity of Nigeria

In plain language

Recent advances in computer vision and machine learning enable automated plant monitoring using drone imagery. This research establishes a practical workflow using the YOLOv5 object detection algorithm and high-resolution aerial photographs to detect and count maize plants across different growth stages. To reduce the manual effort required for data preparation, a semi-automated annotation method using the Segment Anything Model was incorporated. The resulting system successfully identified maize plants at both the three-leaf and seven-leaf developmental stages, achieving strong precision even in challenging field conditions such as overgrown weeds, leaf occlusion, and blurry images. Adding image-rotation data augmentation and tuning noise weights further boosted detection performance. The findings demonstrate a viable framework for characterising crop growth and automating plant counts under realistic agricultural settings.

Key takeaways

  • A workflow combining drone photography with the YOLOv5 model detected and counted maize plants at both three-leaf and seven-leaf growth stages.
  • Applying the Segment Anything Model enabled semi-automated image annotation to reduce manual labelling workload.
  • The model achieved detection precision of 0.828 mAP at the three-leaf stage and 0.863 mAP at the seven-leaf stage.
  • Detection remained effective under adverse field conditions including heavy weed cover, leaf occlusion, and image blur.
  • Techniques such as image-rotation augmentation and low noise weighting provided measurable gains in model accuracy.

Why it matters

Accurate plant counting is essential for assessing crop emergence, estimating yield, and managing field inputs effectively. Traditional manual counting is labour-intensive and slow across large farming areas. By demonstrating that drone images and lightweight computer vision models can reliably count crops amidst weeds and visual clutter, this approach offers an efficient path toward automated, field-scale crop monitoring.

Commercialisation angle

This workflow is relevant to developers of precision agriculture software, drone service providers, and agricultural managers seeking automated crop counting tools. The system demonstrates applied and tested status under realistic field conditions, such as weed-heavy environments. Moving toward commercial deployment would require integrating the pipeline into operational agricultural analytics platforms and testing across a broader variety of field layouts and crop types.

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Abstract

In recent years, computer vision (CV) has made enormous progress and is providing great possibilities in analyzing images for object detection, especially with the application of machine learning (ML). Unmanned Aerial Vehicle (UAV) based high-resolution images allow to apply CV and ML methods for the detection of plants or their organs of interest. Thus, this study presents a practical workflow based on the You Only Look Once version 5 (YOLOv5) and UAV images to detect maize plants for counting their numbers in contrasting development stages, including the application of a semi-auto-labeling method based on the Segment Anything Model (SAM) to reduce the burden of labeling. Results showed that the trained model achieved a mean average precision (mAP@0.5) of 0.828 and 0.863 for the 3-leaf stage and 7-leaf stage, respectively. YOLOv5 achieved the best performance under the conditions of overgrown weeds, leaf occlusion, and blurry images, suggesting that YOLOv5 plays a practical role in obtaining excellent performance under realistic field conditions. Furthermore, introducing image-rotation augmentation and low noise weight enhanced model accuracy, with an increase of 0.024 and 0.016 mAP@0.5, respectively, compared to the original model of the 3-leaf stage. This work provides a practical reference for applying lightweight ML and deep learning methods to UAV images for automated object detection and characterization of plant growth under realistic environments.

Research topics

  • Smart Agriculture and AI
  • Remote Sensing in Agriculture
  • Remote Sensing and LiDAR Applications

Read the original research

This page summarises published work. The authoritative version sits with the publisher.

DOI: 10.3389/fpls.2023.1274813

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