Pansharpening is a crucial image processing technique for numerous remote sensing downstream tasks, aiming to recover high spatial resolution multispectral (HRMS) images by fusing high spatial resolution panchromatic (PAN) images and low spatial resolution multispectral (LRMS) images. Most current mainstream pansharpening fusion frameworks directly learn the mapping relationships from PAN and LRMS images to HRMS images by extracting key features. However, we propose a novel pansharpening method based on the denoising diffusion probabilistic model (DDPM) called PanDiff, which learns the data distribution of the difference maps (DM) between HRMS and interpolated MS (IMS) images from a new perspective. Specifically, PanDiff decomposes the complex fusion process of PAN and LRMS images into a multi-step Markov process, and the U-Net is employed to reconstruct each step of the process from random Gaussian noise. Notably, the PAN and LRMS images serve as the injected conditions to guide the U-Net in PanDiff, rather than being the fusion objects as in other pansharpening methods. Furthermore, we propose a modal intercalibration module (MIM) to enhance the guidance effect of the PAN and LRMS images. The experiments are conducted on a freely available benchmark dataset, including GaoFen-2, QuickBird, and WorldView-3 images. The experimental results from the fusion and generalization tests effectively demonstrate the outstanding fusion performance and high robustness of PanDiff. Fig. 1 depicts the results of the proposed method performed on various scenes. Additionally, the ablation experiments confirm the rationale behind PanDiff’s construction.

Remote sensing (RS) scene classification has attracted extensive attention due to its large number of applications. Recently, convolutional neural network (CNN) methods have shown impressive ability of feature learning in the RS scene classification. However, the performance is still limited by large-scale variance and complex background. To address these problems, we present a multilayer feature fusion network with spatial attention and gated mechanism (MLF2Net_SAGM) for RS scene classification. First, the backbone is employed to extract multilayer convolutional features. Then, a residual spatial attention module (RSAM) is proposed to enhance discriminative regions of the multilayer feature maps, and the key areas can be harvested. Finally, the multilayer spatial calibration features are fused to form the final feature map, and a gated fusion module (GFM) is designed to eliminate feature redundancy and mutual exclusion (FRME). To verify the effectiveness of the proposed method, we conduct comparative experiments based on three widely used RS image scene classification benchmarks. The results show that the direct fusion of multilayer features via element-wise addition leads to FRME, whereas our method fuses multilayer features more effectively and improves the performance of scene classification.

Semantic segmentation for remote sensing images (RSIs) plays an important role in many applications, such as urban planning, environmental protection, agricultural valuation, and military reconnaissance. With the boom in remote sensing technology, numerous RSIs are generated; this is difficult for current complex networks to handle. Efficient networks are the key to solving this challenge. Many previous works aimed at designing lightweight networks or utilizing pruning and knowledge distillation methods to obtain efficient networks, but these methods inevitably reduce the ability of the resulting models to characterize spatial and semantic features. We propose an effective deep supervision-based simple attention network (DSANet) with spatial and semantic enhancement losses to handle these problems. In the network, (1) a lightweight architecture is used as the backbone; (2) deep supervision modules with improved multiscale spatial detail (MSD) and hierarchical semantic enhancement (HSE) losses synergistically strengthen the obtained feature representations; and (3) a simple embedding attention module (EAM) with linear complexity performs long-range relationship modeling. Experiments conducted on two public RSI datasets (the ISPRS Potsdam dataset and Vaihingen dataset) exhibit the substantial advantages of the proposed approach. Our method achieves 79.19% mean intersection over union (mIoU) on the ISPRS Potsdam test set and 72.26% mIoU on the Vaihingen test set with speeds of 470.07 FPS on 512 × 512 images and 5.46 FPS on 6000 × 6000 images using an RTX 3090 GPU.

Extracting 3D building information from monocular satellite sensor imagery remains a formidable challenge in the field of remote sensing. Multitask frameworks based on deep learning, which particularly for simultaneously predicting 2D building outlines and their respective heights using ortho-rectified satellite imagery, have shown promise in addressing this challenge. Height estimation is notably complex due to the absence of explicit height indicators, limited interaction between semantic-height features, and inadequate representation of building relationships. Moreover, the availability of data sources is a limiting factor for broader application. To overcome these issues, this study introduces an innovative instance-level multitask learning model (named BDH-Net) that leverages off-nadir perspectives and roof-to-footprint offset vectors to enhance modeling. This model comprises four key components: a pixel-wise feature extraction image encoder-decoder, a query transformer decoder, a multitask decoder, and a height decoder that employs intra-instance and inter-instance attention for precise building height estimation. Additionally, we pioneer the use of Google Earth imagery to construct an off-nadir satellite dataset with roof-to-footprint offset vectors specifically designed for building instance segmentation and height prediction, known as the BDH dataset. Comprehensive experiments demonstrate that the proposed BDH-Net significantly improves the accuracy of monocular 3D building data extraction by integrating roof-to-footprint offset vectors and leveraging context specific to each building instance. With the extensive coverage and regular updates of Google Earth imagery, BDH-Net holds substantial potential for wide-ranging and long-term applications. The source code of the proposed BDH-Net and the BDH dataset are publicly available at https://github.com/wishx98/BDHNet.