DMCTDet: A density map-guided composite transformer network for object detection of UAV images

The application of unmanned aerial vehicles (UAVs) in urban scene object detection is a vital area of research in urban planning, intelligent monitoring, disaster prevention, and urban surveillance.e However, detecting objects in urban scenes captured by UAVs is a challenging task mainly due to the small size of the objects, the variability within the same class, and the diversity of objects. To design an object detection network that can be applied to complex urban scenes, this study proposes a novel composite transformer object detection network guided by a density map (DMCTDet) for urban scene detection in UAV images. The distributional a priori information of objects can be fully exploited by density maps. In the detection stage, a composite backbone feature extraction network is constructed by Swin Transformer combined with Vision Longformer, which can fully extract the scale-variation objects. Adaptive multiscale feature pyramid enhancement modules (AMFPEM) are inserted in the feature fusion stage between both Swin Transformer and Vision Longformer to learn the relationship between object scale variation and enhance the feature representation capacity of small objects. In this way, the accuracy of urban scene detection is significantly improved, and weak aggregated objects are successfully detected from UAV images. Extensive ablation experiments and comparison experiments. of the proposed network are conducted on publicly available urban scene detection datasets of UAV images. The experimental results demonstrate the effectiveness of the designed network structure and the superiority of the proposed network compared to state-of-the-art methods in terms of detection accuracy.