Unsupervised Change Detection (UCD) in Very High Resolution (VHR) Remote Sensing (RS) images remains to be a difficult challenge due to the inherent spatio-temporal complexity within data. Inspired by recent advancements in Visual Foundation Models (VFMs) and Contrastive Learning (CL), this research aims to develop CL methodologies to translate implicit knowledge in VFM into change representations, thus eliminating the need for explicit supervision. To this end, we introduce a Semantic-to-Change (S2C) learning framework for UCD in VHR RS images. Differently from existing CL methodologies that typically focus on learning multi-temporal similarities, we introduce a novel triplet learning strategy that explicitly models temporal differences, which are crucial to the CD task. Furthermore, random spatial and spectral perturbations are introduced during training to enhance robustness to temporal noise. In addition, a grid sparsity regularization is defined to suppress insignificant changes, and an IoU-matching algorithm is developed to refine the CD results. Experiments on three benchmark CD datasets demonstrate that the proposed S2C learning framework achieves significant improvements in accuracy, surpassing current state-of-the-art by over 31%, 9% and 23%, respectively. It also demonstrates robustness and sample efficiency, suitable for training and adaptation of various VFMs or backbone neural networks.

High-resolution video satellites enable large-view dynamic monitoring for earth observation. Among satellite video interpretation techniques, multi-object tracking (MOT) receives growing attention for its foundational role. Rigid targets in satellite videos exhibit strong inter-frame appearance and posture consistency, showing quasi-linear trajectories with constrained displacements. Inspired by these kinematic characteristics, this paper introduces an online end-to-end P ropagating S patio-temporal S tate and P rogressively A ssociating T rajectory MOT (PS2PAT-MOT) framework. It consists of a detection branch for locating multi-category and multi-target objects in current frame, and a correlation branch using an inter-frame spatio-temporal state propagation (STSP) module to propagate location and appearance information and encode same-target correlations between adjacent frames. Detection and correlation outputs from both branches undergo affinity calculation, while the Progressively Associating Trajectory (PAT) strategy generates continuous tracklets using differentiated association thresholds for distinct trajectory segments. Experimental results on two publicly available AIR-MOT, SAT-MTB, and a self-built LV-SatMOT ( L arge- V iew Sat ellite video MOT ) datasets demonstrate the effectiveness of the proposed PS2PAT-MOT framework. Codes are available at: https://github.com/HELOBILLY/PS2PAT-MOT .

Point cloud classification of airborne light detection and ranging (LiDAR) data is essential to extract geoinformation. Although deep learning provides a new approach for classification, the time-consuming training process and data dependence prevent its widespread application to point clouds. To solve these problems and leverage the potential of high-performing neural networks, we propose an airborne LiDAR point cloud classification method based on transfer learning. A strategy to generate feature images considering the point cloud spatial distribution is first introduced for applying traditional convolutional neural networks to point clouds. Then, transfer learning is used to extract multiscale and multiview deep features. A simple neural network classifier is designed to reduce dimensionality, fuse and learn high-level features, and postprocessing considering contextual information further improves the classification accuracy. We verified the performance of the proposed method through experiments on two airborne LiDAR data sets with different characteristics and containing eight classes. The results demonstrate that the proposed method can achieve a satisfactory classification accuracy with relatively short training time and less training samples than if using conventional methods.

Navigation landmark features such as docks are often used in ships for localization and searching for shore targets during the voyage, which are of great economic and military significance. Continuous and complete dock data could hardly be extracted by existing coast dock extraction method, because the spatial relationships and other characteristics of dock are often ignored which only considers grayscale characteristics of remote sensing image .A dock extraction method based on waterline and perceptual organization is proposed in this paper. To make full use of characteristics spatial relationships, perceptual organization is introduced into dock extraction. Firstly, waterline of coast zone remote sensing image is extracted. Then, perceptual organization and evidence theory are introduced, after which doing perceptual organization based on grayscale characteristics and structural features following the rules of perceptual organization. Finally, evidence is verified to accurately extract dock contours. Experimental results show that the method is able to accurately extract continuous and complete dock contours, providing a new approach for coast dock accurate extraction.