UAV-based remote sensing estimation of above-ground biomass in different crops: A review

• Explained the mechanism of estimating AGB from UAV remote sensing. • Compared the potential and limitations of different types of sensors. • Summarized the model features used to estimate crop AGB. • Analyzed the performance and drawbacks of AGB estimation methods. • Discussed challenges and future directions for UAV-based AGB estimation. Above-ground biomass (AGB) is a measure used to assess crop growth and estimate yield. Accurate, non-destructive and rapid AGB estimation is crucial for advancing modern agriculture. Unlike traditional destructive survey methods, the unmanned aerial vehicle (UAV) remote sensing provides a highly flexible and low-cost way. This study provides a systematic review in terms of UAV-based AGB estimation, including the UAV monitoring mechanisms, UAV platforms, sensors, features, methods, and difficulties and future development directions in AGB estimation. Also, this study subjectively evaluates functions and limitations of different sensors, features, estimation methods, and explores the application and prospects for the development of crop AGB estimation models. Given the current challenges of UAV-based AGB estimation, some important directions for future research are also provided. This review aims to provide practical strategies for future research on estimating AGB and enhancing the efficiency of this technique in assessing crop growth and yield prediction, thereby promoting the development of precision agriculture.