Visualization Techniques for Spray Monitoring in Unmanned Aerial Spraying Systems: A Review

Summary

This narrative review synthesises developments in spray visualization technologies for unmanned aerial spraying systems, examining the physics of droplet formation, atomization, and transport within rotor-induced airflow. The authors evaluate major visualization methods (optical imaging, laser-based scattering, flow-field visualization) and their comparative strengths in spatial resolution and 3D reconstruction, then review experimental evidence from wind-tunnel and field studies demonstrating how downwash flow and tip vortices influence spray deposition patterns. The review identifies emerging techniques including image-based droplet recognition, multimodal data fusion, and data-driven modelling, proposing integrated approaches to drift assessment and spray optimization.

Regional applicability

The technologies and principles reviewed are internationally applicable to precision crop protection; however, the review does not focus on United Kingdom-specific regulatory, environmental, or agronomic contexts. UK practitioners and researchers would need to evaluate transferability of cited visualization methods and spray optimisation strategies to UK climatic conditions, crop types, and pesticide application regulations.

Key measures

Spatial resolution, measurement range, 3D reconstruction capabilities of visualization methods (PDPA/PDIA, HSI, DIH, LD, LiDAR, PIV); droplet size distribution; plume structure; canopy disturbance; deposition patterns

Outcomes reported

This review synthesizes visualization technologies for monitoring spray dynamics in unmanned aerial spraying systems, covering droplet formation, airflow patterns, and deposition across near-field, mid-field, and far-field scales. It evaluates optical imaging, laser-based, and flow-field visualization methods and examines their application in wind-tunnel and field settings.

Topic tags