Enhancing Dense Small Object Detection in UAV Images Based on Hybrid Transformer

Transformer-based models have facilitated significant advances in object detection. However, their extensive computational consumption and suboptimal detection of dense small objects curtail their applicability in unmanned aerial vehicle (UAV) imagery. Addressing these limitations, we propose a hybrid transformer-based detector, H-DETR, and enhance it for dense small objects, leading to an accurate and efficient model. Firstly, we introduce a hybrid transformer encoder, which integrates a convolutional neural network-based cross-scale fusion module with the original encoder to handle multi-scale feature sequences more efficiently. Furthermore, we propose two novel strategies to enhance detection performance without incurring additional inference computation. Query filter is designed to cope with the dense clustering inherent in drone-captured images by counteracting similar queries with a training-aware non-maximum suppression. Adversarial denoising learning is a novel enhancement method inspired by adversarial learning, which improves the detection of numerous small targets by counteracting the effects of artificial spatial and semantic noise. Extensive experiments on the VisDrone and UAVDT datasets substantiate the effectiveness of our approach, achieving a significant improvement in accuracy with a reduction in computational complexity. Our method achieves 31.9% and 21.1% AP on the VisDrone and UAVDT datasets, respectively, and has a faster inference speed, making it a competitive model in UAV image object detection.