Road extraction is a typical task in the semantic segmentation of remote sensing images, and one of the most efficient techniques for solving this task in recent years is the vision transformer technique. However, roads typically exhibit features such as uneven scales and low signal-to-noise ratios, which can be understood as the asymmetry between the road and the background category and the asymmetry in the transverse and longitudinal shape of the road. Existing vision transformer models, due to their fixed sliding window mechanism, cannot adapt to the uneven scale issue of roads. Additionally, self-attention, based on fully connected mechanisms for long sequences, may suffer from attention deviation due to excessive noise, making it unsuitable for low signal-to-noise ratio scenarios in road segmentation, resulting in incomplete and fragmented road segmentation results. In this paper, we propose a road extraction based on deformable self-attention computation, termed DOCswin-Trans (Deformable and Overlapped Cross-Window Transformer), to solve these problems. On the one hand, we develop a DOC-Transformer block to address the scale imbalance issue, which can utilize the overlapped window strategy to preserve the overall contextual semantic information of roads as much as possible. On the other hand, we propose a deformable window strategy to adaptively resample input vectors, which can direct attention automatically to the foreground areas relevant to roads and thereby address the low signal-to-noise ratio problem. We evaluate the proposed method on two popular road extraction datasets (i.e., DeepGlobe and Massachusetts datasets). The experimental results demonstrate that the proposed method outperforms baseline methods. On the DeepGlobe dataset, the proposed method achieves an IoU improvement ranging from 0.63% to 5.01% compared to baseline methods. On the Massachusetts dataset, our method achieves an IoU improvement ranging from 0.50% to 6.24% compared to baseline methods.

Deep neural network-based synthetic aperture radar (SAR) automatic target recognition (ATR) systems are susceptible to attack by adversarial examples, which leads to misclassification by the SAR ATR system, resulting in theoretical model robustness problems and security problems in practice. Inspired by optical images, current SAR ATR adversarial example generation is performed in the image domain. However, the imaging principle of SAR images is based on the imaging of the echo signals interacting between the SAR and objects. Generating adversarial examples only in the image domain cannot change the physical world to achieve adversarial attacks. To solve these problems, this article proposes a framework for generating SAR adversarial examples in a 3D physical scene. First, adversarial attacks are implemented in the 2D image space, and the perturbation in the image space is converted into simulated rays that constitute SAR images through backpropagation optimization methods. The mapping between the simulated rays constituting SAR images and the 3D model is established through coordinate transformation, and point correspondence to triangular faces and intensity values to texture parameters are established. Thus, the simulated rays constituting SAR images are mapped to the 3D model, and the perturbation in the 2D image space is converted back to the 3D physical space to obtain the position and intensity of the perturbation in the 3D physical space, thereby achieving physical adversarial attacks. The experimental results show that our attack method can effectively perform SAR adversarial attacks in the physical world. In the digital world, we achieved an average fooling rate of up to 99.02% for three objects in six classification networks. In the physical world, we achieved an average fooling rate of up to 97.87% for these objects, with a certain degree of transferability across the six different network architectures. To the best of our knowledge, this is the first work to implement physical attacks in a full physical simulation condition. Our research establishes a theoretical foundation for the future concealment of SAR targets in practical settings and offers valuable insights for enhancing the attack and defense capabilities of subsequent DNNs in SAR ATR systems.

Remote sensing change detection (RS-CD) relies on the model’s ability to learn features of marked change objects, known as foreground targets. Beyond foreground targets, the background targets are more valuable samples for change detection, such as unlabelled ones, semantically ambiguous ones, pseudo changes, and non-interesting changes, referred to as hard case samples (HCSs) in this paper. There are two additional challenges to learning HCSs: (1) the loss function focusing on the foreground targets with rich labels and ignoring the HCSs in the background, called the imbalance problem. (2) It is difficult for a model to learn the change information of HCSs directly, which is called HCSs missingness. This paper proposed a foreground association-driven Siamese network with hard sample optimization (HASNet). To deal with the imbalance problem, we propose an equilibrium optimization loss function to regulate the optimization focus of the foreground and background, determine the HCSs through the distribution of the loss values, and introduce dynamic weights in the loss term to gradually shift the optimization focus of the loss from the foreground to the background hard cases as the training progresses. To address the HCSs missingness, we propose the scene-foreground association module by using potential remote sensing spatial scene information to model the association between the target of interest in the foreground and the related context to obtain scene embedding to reinforce the feature of hard cases. Experiments on four public datasets with 11 baselines show that HASNet outperforms current state-of-the-art CD methods, particularly in detecting HCSs. The source code is available at https://github.com/GeoX-Lab/HASNet.

Predicting urban morphology based on local attributes is an important issue in urban science research. The deep generative models represented by generative adversarial network (GAN) models have achieved impressive results in this area. However, in such methods, the urban morphology is assumed to follow a specific probability distribution and be able to directly approximate the distribution via GAN models, which is not a realistic strategy. As demonstrated by the score-based model, a better strategy is to learn the gradient of the probability distribution and implicitly approximate the distribution. Therefore, in this paper, an urban morphology prediction method based on the conditional diffusion model is proposed. Implementing this approach results in the decomposition of the attribute-based urban morphology prediction task into two subproblems: estimating the gradient of the conditional distribution, and gradient-based sampling. During the training stage, the gradient of the conditional distribution is approximated by using a conditional diffusion model to predict the noise added to the original urban morphology. In the generation stage, the corresponding conditional distribution is parameterized based on the noise predicted by the conditional diffusion model, and the final prediction result is generated through iterative sampling. The experimental results showed that compared with GAN-based methods, our method demonstrated improvements of 5.5%, 5.9%, and 13.2% in the metrics of low-level pixel features, shallow structural features, and deep structural features, respectively.

The existing change detection (CD) methods can be summarized as the visual-first change detection (ViFi-CD) paradigm, which first extracts change features from visual differences and then assigns them specific semantic information. However, CD is essentially dependent on change regions of interest (CRoIs), meaning that the CD results are directly determined by the semantics changes in interest, making its primary image factor semantic of interest rather than visual. The ViFi-CD paradigm can only assign specific semantics of interest to specific change features extracted from visual differences, leading to the inevitable omission of potential CRoIs and the inability to adapt to different CRoI CD tasks. In other words, changes in other CRoIs cannot be detected by the ViFi-CD method without retraining the model or significantly modifying the method. This paper introduces a new CD paradigm, the semantic-first CD (SeFi-CD) paradigm. The core idea of SeFi-CD is to first perceive the dynamic semantics of interest and then visually search for change features related to the semantics. Based on the SeFi-CD paradigm, we designed Anything You Want Change Detection (AUWCD). Experiments on public datasets demonstrate that the AUWCD outperforms the current state-of-the-art CD methods, achieving an average F1 score 5.01% higher than that of these advanced supervised baselines on the SECOND dataset, with a maximum increase of 13.17%. The proposed SeFi-CD offers a novel CD perspective and approach.

Synthetic Aperture Radar (SAR) target detection models are highly vulnerable to adversarial attacks, which significantly reduce detection performance and robustness. Existing adversarial SAR target detection approaches mainly focus on the image domain and neglect the critical role of signal propagation, making it difficult to fully capture the connection between the physical space and the image domain. To address this limitation, we propose an Echo Signal-Guided Adversarial Example Generation method for SAR target detection (SAR-ESAE). The core idea is to embed adversarial perturbations into SAR echo signals and propagate them through the imaging and inverse scattering processes, thereby establishing a unified attack framework across the signal, image, and physical spaces. In this way, perturbations not only appear as pixel-level distortions in SAR images but also alter the scattering characteristics of 3D target models in the physical space. Simulation experiments in the Scenario-SAR dataset demonstrate that the SAR-ESAE method reduces the mean Average Precision of the YOLOv3 model by 23.5% and 8.6% compared to Dpatch and RaLP attacks, respectively. Additionally, it exhibits excellent attack effectiveness in both echo signal and target model attack experiments and exhibits evident adversarial transferability across detection models with different architectures, such as Faster-RCNN and FCOS.