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Asian and Pacific Conference on Synthetic Aperture Radar (APSAR)

作者： Junying Yang Xiaolan Qiu Lihua Zhong Chibiao Ding Lijia Huang Hao Chen Key Laboratory of Technology in Geo-Spatial Information Processing and Application Systems Institute of Electronics Chinese Academy of Sciences Beijing China Fifth Laboratory Institute of Communication and Tracking Technology Beijing China

ISBN: (数字)9781728129129

ISBN: (纸本)9781728129136

Gaofen-3 (GF-3) is the first Chinese multichannel synthetic aperture radar (SAR) sensor that can operate in the dual receive channel (DRC) mode. Different from the traditional single-channel SAR system, the multichannel SAR system can overcome the inherent limitation to achieve high-resolution and wide-swath (HRWS) at the same time. However, the key challenge it faces is false target suppression. Especially for the moving vessels on the ocean, the existence of false targets will increase false alarm probability and affect the interpretation of SAR images. In this paper, the method of integration of detection, velocity estimation, location, and imaging for moving targets in the HRWS SAR system is proposed as well as applied to get an unambiguous image. The simulation and GF-3 real data experimental results show the validity of the method.

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Progressive unsupervised person re-identification by tracklet association with spatio-temporal regularization

arXiv

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arXiv 2019年

作者： Xie, Qiaokang Zhou, Wengang Qi, Guo-Jun Tian, Qi Li, Houqiang CAS Key Laboratory of Technology in Geo-spatial Information Processing and Application System Department of Electronic Engineering and Information Science University of Science and Technology of China Hefei230027 China Huawei Cloud EI Product Department Huawei Noah's Ark Laboratory

Existing methods for person re-identification (Re-ID) are mostly based on supervised learning which requires numerous manually labeled samples across all camera views for training. Such a paradigm suffers the scalability issue since in real-world Re-ID application, it is difficult to exhaustively label abundant identities over multiple disjoint camera views. To this end, we propose a progressive deep learning method for unsupervised person Re-ID in the wild by Tracklet Association with Spatio-Temporal Regularization (TASTR). In our approach, we first collect tracklet data within each camera by automatic person detection and tracking. Then, an initial Re-ID model is trained based on within-camera triplet construction for person representation learning. After that, based on the person visual feature and spatio-temporal constraint, we associate cross-camera tracklets to generate cross-camera triplets and update the Re-ID model. Lastly, with the refined Re-ID model, better visual feature of person can be extracted, which further promote the association of cross-camera tracklets. The last two steps are iterated multiple times to progressively upgrade the Re-ID model. To facilitate the study, we have collected a new 4K UHD video dataset named Campus-4K with full frames and full spatio-temporal information. Experimental results show that with the spatio-temporal constraint in the training phase, the proposed approach outperforms the state-of-the-art unsupervised methods by notable margins on DukeMTMC-reID, and achieves competitive performance to fully supervised methods on both DukeMTMC-reID and Campus-4K datasets. Copyright © 2019, The Authors. All rights reserved.

关键词： Cameras

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An accurate SAR imaging method based on generalized minimax concave penalty 12

An accurate SAR imaging method based on generalized minimax ...

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12th European Conference on Synthetic Aperture Radar, EUSAR 2018

作者： Wei, Zhonghao Zhang, Bingchen Han, Bing Xu, Zhilin Hong, Wen Wu, YiRong University of Chinese Academy of Science and Key Laboratory of Technology in Geo-spatial Information Processing and Application Systems Institute of Electronics Chinese Academy of Sciences China Laboratory of Technology in Geo-spatial Information Processing and Application Systems Institute of Electronics Chinese Academy of Sciences China Institute of Electronics Chinese Academy of Sciences China

ISBN: (纸本)9783800746361

Sparse signal processing has been applied in synthetic aperture radar (SAR) imaging successfully. As a typical sparse reconstruction model, L1 regularization often underestimates the intensities of the targets. The estimated radar cross section (RCS) is related to the pixel intensity. The underestimation will cause the errors in RCS estimations. In this paper, we present a SAR imaging method based on generalized minimax convex (GMC) penalty, which can avoid the pixel intensity underestimation. The performance of the proposed method is verified using simulations and real data. © VDE VERLAG GMBH Â Berlin Â Offenbach.

关键词： Radar cross section

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Torque work of origin-destination flows: Quantifying urban place centrality from a physical perspective

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Computers, Environment and Urban systems 2025年 121卷

作者： Xiaorui Yan Tao Pei Ci Song Zidong Fang Xiaohan Liu Tianyu Liu Linfeng Jiang Ying Gao Guangdong Li Jie Huang Yaqin Sun State Key Laboratory of Resources and Environmental Information System Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences Beijing China University of Chinese Academy of Sciences Beijing China Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application Nanjing China College of Earth and Environmental Sciences Lanzhou University Lanzhou China Key Laboratory of Regional Sustainable Development Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing China School of Environment and Spatial Informatics China University of Mining and Technology Xuzhou China

Quantifying urban place centrality, defined as its relative importance in serving its peripheral areas, provides insights into urban structures, optimizes resource allocation, and supports strategic urban planning. Centrality is shaped by three aspects: service volume, spatial reach, and directional diversity. However, existing measures often assess these factors separately and few integrate them simultaneously. Additionally, centrality analyses often overlook local perspectives and intra-day dynamics. To this end, we propose a novel origin-destination flow-based centrality measure, namely Total Torque Work (TTW), that integrates these three aspects into a single value, conceptualized as “Torque work of flow”, where flow volume, length, and direction correspond to the force magnitude, lever arm, and angular displacement. The effectiveness of the TTW is validated by simulation experiments. We apply this measure to analyze macro- and micro-centralities in Beijing, using taxi and shared bike flow data. Macro-centrality shows a monocentric structure, with higher values near railway stations, airports, and business and commercial centers. Micro-centrality is more polycentric, with subway stations exhibiting higher centrality. Time series clustering identifies three temporal patterns in both macro- and micro-centralities: two “daytime-dominant” patterns linked to multifunctional activities and commuting, and a “nighttime-dominant” pattern in residential areas. The study concludes with several implications for urban planning, emphasizing the importance of incorporating multi-spatiotemporal scales.

关键词： Intra-day dynamic Multiscale analysis Origin-destination flows Place centrality Torque work Urban science

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Regulation effect of planted forests on land surface temperature in China

引用

Agricultural and Forest Meteorology 2025年 372卷

作者： Zhijiang Zhang Kai Yang Lunche Wang Kai Cheng Chao Chen Chao Ding School of Geography Science and Geomatics Engineering Suzhou University of Science and Technology Suzhou 215009 China SuZhou Key Laboratory of Spatial Information Intelligent Technology and Application Suzhou University of Science and Technology Suzhou 215009 China School of Geography and Information Engineering China University of Geosciences Wuhan 430074 China Institute of Remote Sensing and Geographic Information System School of Earth and Space Sciences Peking University Beijing 100871 China Institute of Ecology College of Urban and Environmental Sciences Peking University Beijing 100871 China Department of Geographic Science Faculty of Arts and Sciences Beijing Normal University Zhuhai 519087 China

Afforestation has been regarded as a potentially effective strategy for the mitigation of climate warming. China has the largest planted forest area worldwide benefited by a series of large-scale afforestation and reforestation project since the 1970s. The planted forests (PF) have been widely reported as an enduring carbon sink. However, the climatic regulation effect of PF on climate through biophysical process remains unclear. To this end, we utilized satellite observations to quantify the impact of the conversion of grasslands (GRA), croplands (CRO) and natural forests (NF) to PF on land surface temperature (LST) between 2003 and 2012 and illustrated the underlying biophysical mechanisms based on a revised Intrinsic Biophysical Mechanism (IBM) method. The results indicated that afforestation of PF caused negligible daily cooling effect (−0.005 ± 0.002 K) compared with NF while induced obvious daily cooling effect compared with GRA (−0.253 ± 0.004 K) and CRO (−0.162 ± 0.002 K). We also demonstrated that the revised IBM attribution method is applicable in interpreting the biophysical mechanism of PF on LST. Attribution analysis revealed that the surface roughness and Bowen ratio dominated the cooling effect as the surface became rougher and more evaporative cooling after converting NF, GRA, or CRO to PF. The contributions of albedo were less stark compared with other components and presented a weak warming effect. Furthermore, the atmospheric feedback was proved that have a pronounced impact on LST and should be included in the attribution of LST change. This study focuses on the potential of PF afforestation to provide local climate adaptation benefits, filling the gaps of previous studies involved to biophysical effect failure in distinguishing NF and PF, and provides new guidance for local climate impact evaluation when implementing forestry projects.

关键词： Planted forests Surface temperature Biophysical effect Intrinsic biophysical mechanism Climate mitigation

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Transform-Invariant Convolutional Neural Networks for Image Classification and Search

arXiv

引用

arXiv 2019年

作者： Shen, Xu Tian, Xinmei He, Anfeng Sun, Shaoyan Tao, Dacheng CAS Key Laboratory of Technology in Geo-spatial Information Processing and Application System University of Science and Technology of China Hefei Anhui230027 China Centre for Quantum Computation & Intelligent Systems Faculty of Engineering and Information Technology University of Technology Sydney UltimoNSW2007 Australia

Convolutional neural networks (CNNs) have achieved state-of-the-art results on many visual recognition tasks. However, current CNN models still exhibit a poor ability to be invariant to spatial transformations of images. Intuitively, with sufficient layers and parameters, hierarchical combinations of convolution (matrix multiplication and nonlinear activation) and pooling operations should be able to learn a robust mapping from transformed input images to transform-invariant representations. In this paper, we propose randomly transforming (rotation, scale, and translation) feature maps of CNNs during the training stage. This prevents complex dependencies of specific rotation, scale, and translation levels of training images in CNN models. Rather, each convolutional kernel learns to detect a feature that is generally helpful for producing the transform-invariant answer given the combinatorially large variety of transform levels of its input feature maps. In this way, we do not require any extra training supervision or modification to the optimization process and training images. We show that random transformation provides significant improvements of CNNs on many benchmark tasks, including small-scale image recognition, large-scale image recognition, and image retrieval. The code is available at https: ACM ISBN 978-1-4503-2138-9. Copyright © 2019, The Authors. All rights reserved.

关键词： Image recognition

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A TOPSAR Calibration Method for processing system of GF3 Next Generation 6

A TOPSAR Calibration Method for Processing System of GF3 Nex...

引用

6th Asia-Pacific Conference on Synthetic Aperture Radar, APSAR 2019

作者： Yin, Di Han, Bing Sun, Jili Chen, Aiping Zhao, Liangbo Yuan, Xinzhe Zhong, Lihua Hu, Yuxin University of Chinese Academy of Sciences Beijing100049 China Institute of Electronics Chinese Academy of Sciences Beijing100190 China Beijing Institute of Telemetry and Telecommunications Technology Beijing100094 China Chinese Academy of Space Technology Beijing100094 China National Satellite Ocean Application Service State Oceanic Administration Beijing100081 China Key Laboratory of Technology in Geo-Spatial Information Processing and Application Systems Institute of Electronics Chinese Academy of Sciences Beijing100190 China

ISBN: (纸本)9781728129129

TOPSAR is an earth-imaging technique, which can provide wide swath coverage. The paper introduces a TOPSAR focusing and calibrating experiment based on the TOPSAR data acquired by Gaofen3(GF3). In this paper, we firstly derive the processor calibration factors under the demands of keeping signal energy invariant. After that, we fully analyze the impact of antenna electronic steering on TOPSAR products. Aimed to be applied to TOPSAR mode processing system of a SAR satellite, the next generation of GF3, calibration methods to processor and electronic steering was proposed in this paper. © 2019 IEEE.

关键词： Calibration

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Patch reordering: A novel way to achieve rotation and translation invariance in convolutional neural networks

arXiv

引用

arXiv 2019年

作者： Shen, Xu Tian, Xinmei Sun, Shaoyan Tao, Dacheng CAS Key Laboratory of Technology in Geo-spatial Information Processing and Application System University of Science and Technology of China Hefei Anhui230027 China Centre for Artificial Intelligence Faculty of Engineering and Information Technology University of Technology Sydney 81 Broadway Street UltimoNSW2007 Australia

Convolutional Neural Networks (CNNs) have demonstrated state-of-the-art performance on many visual recognition tasks. However, the combination of convolution and pooling operations only shows invariance to small local location changes in meaningful objects in input. Sometimes, such networks are trained using data augmentation to encode this invariance into the parameters, which restricts the capacity of the model to learn the content of these objects. A more efficient use of the parameter budget is to encode rotation or translation invariance into the model architecture, which relieves the model from the need to learn them. To enable the model to focus on learning the content of objects other than their locations, we propose to conduct patch ranking of the feature maps before feeding them into the next layer. When patch ranking is combined with convolution and pooling operations, we obtain consistent representations despite the location of meaningful objects in input. We show that the patch ranking module improves the performance of the CNN on many benchmark tasks, including MNIST digit recognition, large-scale image recognition, and image retrieval. The code is available at https://***//jasonustc/caffe-multigpu/tree/TICNN. Copyright © 2019, The Authors. All rights reserved.

关键词： Convolution

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Recent Widespread Deceleration of Global Surface Urban Heat Islands Unveiled by Satellites

引用

geophysical Research Letters 2025年第12期52卷

作者： Wenfeng Zhan Long Li T. C. Chakraborty Leiqiu Hu Dazhong Wang Weilin Liao Shasha Wang Huilin Du Fan Huang Chunli Wang Zihan Liu Manchun Li Jiangsu Provincial Key Laboratory for Advanced Remote Sensing and Geographic Information Technology International Institute for Earth System Science Nanjing University Nanjing China Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application Nanjing China Frontiers Science Center for Critical Earth Material Cycling Nanjing University Nanjing China Pacific Northwest National Laboratory Richland WA USA Department of Atmospheric Science University of Alabama in Huntsville Huntsville AL USA Guangdong Key Laboratory for Urbanization and Geo-Simulation School of Geography and Planning Sun Yat-sen University Guangzhou China School of Geography and Ocean Science Nanjing University Nanjing China

Tracking the temporal dynamics of urban heat island (UHI) is critical for urban heat adaptation and mitigation strategies. However, whether UHI trends have shifted recently and their underlying drivers remain unknown. Here we investigate the variabilities in surface UHI trends and their associated determinants in 2,104 cities worldwide from 2000 to 2022. Our findings reveal that approximately half of the world's cities have experienced notable shifts in surface UHI trends, predominantly characterized by UHI deceleration. These shifts can be primarily attributed to alterations in vegetation trends during the day and to modifications in surface albedo and local warming trends at night. Our study challenges the conventional linear models commonly employed to estimate surface UHI trends, suggesting potential biases in such estimates. Our findings underscore the need for nuanced policies to curtail UHI growth by considering changes in urban underlying surfaces and background climate, particularly from a nonlinear perspective. Satellite records reveal that almost half of the world's cities experienced changes in urban heat island (UHI) trends, mainly slowdowns The UHI deceleration occurs at a more rapid speed in larger cities and old urban area as compared to smaller cities and newly urbanized area The changes in UHI trends are intricately regulated by nonlinear changes in urbanization processes and background climate changes Cities worldwide have witnessed a pervasive upward trend in surface urban heat island (UHI). However, it remains unclear whether this trend has changed. Here we reveal approximately half of the world's cities experiencing significant shifts in surface UHI trends, primarily characterized by deceleration. These shifts are mainly regulated by local changes in vegetation, albedo and air temperature. Our research underscores the limited understanding of temporal dynamics of surface UHI, offering the first indication of global prevalence of nonlinear trend

关键词： urban heat island land surface temperature interannual variation urban heat mitigation urban renewal

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Warning of Rainfall-Induced Landslide in Bazhou District

Warning of Rainfall-Induced Landslide in Bazhou District

引用

IEEE International Symposium on geoscience and Remote Sensing (IGARSS)

作者： Mujie Li Mingcang Zhu Yang Hec Zhanyong He Na Wang Zezhong Zheng Guoqing Zhou School of Resources and Environment University of Electronic Science and Technology of China Chengdu Sichuan PRC Chengdu Sichuan PRC Sichuan Research Institute for Eco-system Restoration & Geo-disaster Prevention Chengdu Sichuan PRC Guangxi Key Laboratory for Spatial Information and Geomatics Guilin University of Technology Guilin Guangxi PRC

ISBN: (数字)9781728163741

ISBN: (纸本)9781728163758

Landslide disasters have caused incalculable losses to human. In China, 90% occurrence of landslides are directly induced by rainfall or indirectly related to rainfall. Because of its geographical location and the climate that belongs to the subtropical monsoon humid climate, the proportion of rainfall-induced landslides accounts for more than 70% of the total geological disasters in Bazhou district. In this paper, based on the geographic information system (GIS) technology, combined with the historical landslide hazard data, we conducted a study on landslide probabilistic quantitative model composed of landslide susceptibility evaluation and the rainfall intensity-duration threshold model. The research results showed that the prediction accuracy of rainfall model is 81.82%. And the landslide hazard prediction was carried out for rainfall-induced landslides and potential landslides, with a prediction accuracy of 90.91%. The research results showed that the meteorological early warning model results were consistent with the actual inspection results.

关键词： Terrain factors Biological system modeling Data models Predictive models Support vector machines Neural networks Hazards

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