High-Frequency Semantics and Geometric Priors for End-to-End Detection Transformers in Challenging UAV Imagery

Unmanned Aerial Vehicle-based Object Detection (UAV-OD) faces substantial challenges, including small target sizes, high-density distributions, and cluttered backgrounds in UAV imagery. Current algorithms often depend on hand-crafted components like anchor boxes, which demand fine-tuning and exhibit limited generalization, and Non-Maximum Suppression (NMS), which is threshold-sensitive and prone to misclassifying dense objects. These generic architectures thus struggle to adapt to aerial imaging characteristics, resulting in performance limitations. Moreover, emerging end-to-end frameworks have yet to effectively mitigate these aerial-specific challenges.To address these issues, we propose HEGS-DETR, a comprehensively enhanced, real-time Detection Transformer framework tailored for UAVs. First, we introduce the High-Frequency Enhanced Semantics Network (HFESNet) as a novel backbone. HFESNet preserves critical high-frequency spatial details to extract robust semantic features, thereby improving discriminative capability for small and occluded targets in complex backgrounds. Second, our Efficient Small Object Pyramid (ESOP) strategy strategically fuses high-resolution feature maps with minimal computational overhead, significantly boosting small object detection. Finally, the proposed Selective Query Recollection (SQR) and Geometry-Aware Positional Encoding (GAPE) modules enhance the detector's decoder stability and localization accuracy, effectively optimizing bounding boxes and providing explicit spatial priors for dense scenes. Experiments on the VisDrone dataset demonstrate that HEGS-DETR achieves a 5.1% AP50 and 3.8% AP increase over the baseline, while maintaining real-time speed and reducing parameter count by 4M.