BDTNet: Road Extraction by Bi-Direction Transformer From Remote Sensing Images

The past several years have witnessed the rapid development of the task of road extraction in high-resolution remote sensing images. However, due to the complex background and road distribution, road extraction is still a challenging research in remote sensing images. In convolutional neural networks (CNNs), the U-shaped architecture network has shown its effectiveness. But the global representation cannot be captured effectively by CNNs. While in the transformer, the self-attention (SA) module can capture the long-distance feature dependencies. A hybrid encoder–decoder method called bi-direction transformer network (BDTNet) is proposed in this letter, which enhances the extraction of global and local information in remote sensing images. First, feature maps of different scales are obtained through the backbone network. And then, on the basis of reducing the computational cost of SA, the bi-direction transformer module (BDTM) is constructed to capture the contextual road information in feature maps of different scales. Finally, the feature refinement module (FRM) is introduced to integrate the features extracted from the backbone network and BDTM, which enhance the semantic information of the feature maps and obtain more detailed segmentation results. The results show that the proposed method achieved a high intersection over union (IoU) of 67.09% in the DeepGlobe dataset. Extensive experiments also verify the effectiveness of the proposed method on three public remote sensing road datasets.