ADD-YOLO: An algorithm for detecting animals in outdoor environments based on unmanned aerial imagery

Abstract

The breeding management of extensive livestock and scientific research surveys of animals in outdoor environments often require the utilization of UAVs due to their ability to efficiently cover large areas at a cost-effective rate. However, identifying small animal targets in aerial imagery from high-altitudes remains a significant challenge. This paper introduces an enhanced algorithm based on YOLOv8n, specifically designed for aerial animal detection. Firstly, we add a P2 small target detection layer on top of the original baseline model, while removing the P5 large target detection layer and 32x downsampling to enhance the detection of small animal targets and reduce the number of model parameters. Secondly, The improved N-SPPCSPC module replaces the spatial pyramid pooling structure in the baseline model to enhance the extraction capability for small targets. Thirdly, an improved DWRC2f module is adopted to enhance the extraction of multi-scale contextual information. Fourthly, the SEAM module is incorporated before the detection head to enhance the detection of occluded and overlapping animals. Finally, a combined NWD Loss function is implemented to address the scale sensitivity of IoU Loss, thereby improving the accuracy of small target detection. Compared to the baseline model, the improved model achieved an increase of 7.1% and 4.9% in mAP50 values and an increase of 4.0% and 1.3% in mAP50-95 values, respectively, across two datasets, while significantly reducing the number of parameters. Further comparisons with other single-stage object detection models demonstrate a better robustness of our model. Additionally, after quantization, when testing the inference speed of ADD-YOLO on performance-constrained edge devices, it was 1.72 times and 1.81 times faster than the baseline model. Therefore, this model provides a new and efficient monitoring tool for extensive pastoral management and wildlife surveys.