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Table of Content

    20 May 2023, Volume 52 Issue 5
    Express Paper
    Rapid response to Turkey-Syria earthquake using night-time light remote sensing
    LI Xi, GONG Yu, CAO Hanrui
    2023, 52(5):  697-705.  doi:10.11947/j.AGCS.2023.20230503
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    On February 6, 2023, Mw7.8 and Mw7.5 earthquakes hit Turkey successively, causing heavy losses of lives and property in Turkey and Syria. This letter introduces the research team at Wuhan University, under the framework of the Group on Earth Observations (GEO), collaborated with the United Nations Satellite Centre to implement damage assessment of the earthquake through night-time light remote sensing. The process mainly includes the satellite emergency photography, data processing and data analysis, etc. The NPP-VIIRS night-time light images were used to conduct a large-scale loss assessment of the affected cities, and the SDGSAT-1 and Yangwang-1 high-resolution night-time light images were used to carry out fine-scale analysis of Adiyaman and Antakya, which are two severely hit cities. On this basis, the article also introduces how to release the Turkey-Syria earthquake assessment report to the world through the framework of international collaboration. This work proves that night-time light remote sensing can carry out emergency response to major natural disasters, and can complement day-time remote sensing to conduct rapid assessment of disasters at large scale.
    Geodesy and Navigation
    Improved function filter and its application in airborne gravimetry
    LIU Lintao, LIANG Xinghui, LANG Junjian, SHI Zhimin, YAO Yanji, HU Huiwen, SHEN Cong
    2023, 52(5):  706-713.  doi:10.11947/j.AGCS.2023.20210515
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    In this paper, a novel function filter is constructed, which is composed of a parameterized Gaussian function and a scaled Shannon function. It can realize low pass, band pass and high pass filtering for time series. The frequency response function of the filter is flat in the filtering band and the transition band is smooth. The innovation of this paper is that the truncation frequency and the length of the transition band of the function filter are controlled independently by the scale parameter of the Shannon function and the window width parameter of the Gaussian function, which makes the filter have good design flexibility. Because the filter is continuous and differentiable, it can be used to filter the random sampling rate time series. The simulation results show that the filter has good filtering accuracy. This filter is applied to the airborne gravimetry data filtering processing, and the airborne gravimetry results of the 7 km scale are obtained simply and accurately. The invention of this filter makes filtering (low pass, band pass and high pass) simple and efficient.
    Drought characteristics of the Yellow River basin from 2002 to 2020 revealed by GRACE and GRACE Follow-On data
    QU Wei, JIN Zehui, ZHANG Qin, GAO Yuan, ZHANG Pufang
    2023, 52(5):  714-724.  doi:10.11947/j.AGCS.2023.20210458
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    The study on the temporal and spatial variation characteristics of drought in the Yellow River basin is of great significance to understand the evolution law of water resources in the Yellow River basin. We make full use of the advantages of GRACE (gravity recovery and climate experiment) and GRACE-FO (GRACE Follow-On)data in monitoring hydrological information changes on a large scale, to calculate the terrestrial water storage anomaly (TWSA) and the corresponding water storage deficit index (WSDI) of the Yellow River basin based on GRACE and GRACE-FO RL06 Mascon data from April 2002 to July 2020.Based on the above analysis revealed by the WSDI, the drought events and their severity, drought duration, average and maximum water reserve deficit in the upper, middle and lower reaches of the Yellow River basin are analyzed. In addition, these analysis are compared with the recognition results of other four commonly drought indexes, standardized precipitation evaporation index (SPEI), self correct-Palmer drought severity index (sc-PDSI), standardized precipitation index (SPI), and standardized runoff index (SRI). The results show that in the five periods of drought events and their corresponding drought grades in the upper reaches, middle and lower reaches of the Yellow River basin identified by WSDI, there are other unidentified phenomena of traditional drought indexes.In the past drought event identification in the Yellow River basin, WSDI shows significant identification advantages over the other four traditional drought indexes. Compared with traditional drought indicators that mainly rely on sparse surface hydrological monitoring information, WSDI drought indicator based on gravity satellite monitoring data can effectively identify the characteristics of watershed drought on a large scale.
    Optimization of variational Bayesian-based adaptive filter for closed-loop feedback in integrated navigation
    LI Zengke, SUN Yaowen, CHEN Zhaobing, ZHAO Long, GAO Jingxiang
    2023, 52(5):  725-737.  doi:10.11947/j.AGCS.2023.20210689
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    Multi-sensor combination can deal with navigation and positioning problems in the case of GNSS signals being blocked and interfered. Filtering method is one of the most commonly adopted methods for multi-source data fusion in navigation and positioning. In the filtering process, the system noise and measurement noise of integrated navigation in the dynamic process cannot be accurately determined, so the adaptive filtering method is always used to balance the time update and measurement update. The Bayesian adaptive filtering method has good effect in many occasions, but it needs to select the adaptive factor just like other adaptive filtering methods. Based on the real-time requirement of integrated navigation and the particularity of closed-loop feedback, the Bayesian adaptive filtering is adopted and optimized in this paper and the dynamic calculation of adjusting factor is presented. Finally, the combination of GNSS and inertial navigation system (INS) is taken as an example to verify the effectiveness by simulation and actual experiment. The experimental results show that the algorithm proposed in this paper can obtain high-precision results without iterative calculation, which improves the computational efficiency. For real dynamic scenes, the result is more advantageous due to the dynamic adaptive adjustment factors.
    Hybrid SVM and HMM based navigation context awareness models for overwater and underwater mixed scene
    ZHU Feng, LUO Kegan, CHEN Weijie, LIU Wanke, ZHANG Xiaohong
    2023, 52(5):  738-747.  doi:10.11947/j.AGCS.2023.20220013
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    Navigation context awareness is not only an important feature of intelligent PNT (positioning, navigation and timing), but also the basis for realizing multi-scene seamless navigation and positioning. This paper focuses on the overwater and underwater scene, which is divided into three kinds of subdivide scenes: overwater, shallow water and deep water according to the change of GNSS signal characteristics, using support vector machine (SVM) for scene classification and recognition. On this basis, hidden Markov model (HMM) is introduced to express navigation scene switching to further improve the reliability of context awareness. This paper constructs two kinds of context awareness models based on result combination (SVM-HMM1) and probability combination (SVM-HMM2). The recognition accuracy of SVM-HMM1 and SVM-HMM2 are 91.36% and 95.11%, respectively. Compared with HMM and SVM, the combined models are more stable in result classification and recognition, and the accuracies are improved by about 0.95%~8.46%.
    Design and implementation of ultra-high-degree spherical harmonic model of earth topography
    SHAN Jianchen, LI Shanshan, FAN Diao, LI Xinxing, HUANG Yan, XING Zhibin
    2023, 52(5):  748-759.  doi:10.11947/j.AGCS.2023.20220003
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    Aiming at solving the problems of calculation accuracy, stability and the large scale operations in the construction of 10 800 degree spherical harmonic of topography, the experiments were carried out. For the first part, Driscoll/Healy quadrature was proved to have higher computational accuracy by comparing and analyzing rectangular discrete quadrature, Gauss-Legendre quadrature and Driscoll/Healy quadrature. For the second part, a modified Belikov formula was given, which could make sure that fnALF is recursed to order 10 800 with better accuracy than 10-12 in the full latitude range. Also, an optimization strategy was proposed for computing ultra-high-degree spherical harmonic coefficients by combining FFT and multi-core parallel technology based on OpenMP, which significantly improved the computational efficiency. For the last part, the 10 800 degree spherical harmonic model of topography, sph. 10 800_IEU, whose overall accuracy was similar to Earth2014_TBI2014.shc, was established by using the grid data of model Earth2014_TBI and model STO_IEU2020, however, its relative precision in the experimental areas was proved slightly better than that of model Earth2014_TBI2014.shc.
    The improvement of star target region extraction algorithm for star centroid
    XU Bin, ZHENG Yong, CHEN Zhanglei, CHEN Bing, CHEN Xiao, LI Chonghui
    2023, 52(5):  760-768.  doi:10.11947/j.AGCS.2023.20210674
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    The extraction of the target area of star points in star maps is related to the accuracy of the star centroid, which is crucial for celestial navigation. In this paper, an improved algorithm for multi-star target region extraction of a large-field-view star map is proposed to solve the problems of the poor real-time performance of existing boundary search algorithms, the invalidity of boundary search calculation of individual star points, and the inability to recognize and process multiple star points in a single visual frame. The process is as follows: firstly, the visual frame extraction algorithm is used to preliminarily extract the target region. Then, the single-star target region and the target region which may contain multiple stars are screened out by using the diagonal decision algorithm established in this paper. Finally, the boundary search algorithm is used to extract the target region of each star and realize the recognition of the target region of multiple stars. The processing results of measured star maps show that the efficiency of the proposed algorithm is 48% higher than that of the boundary search algorithm. When the visual frame size ranges from 16 to 60 pixels, the accuracy rate of multi-star target region extraction is better than 98%, which can eliminate the star centroid error of nearly 10 pixel caused by the visual frame extraction algorithm, and improve the overall extraction accuracy of star centroid by 3.78 times, reaching 0.038 pixels.
    Photogrammetry andRemote Sensing
    Classification of basic deformation products of L-band differential interfero-metric SAR satellite
    LI Tao, TANG Xinming, LI Shijin, ZHOU Xiaoqing, ZHANG Xiang, XU Yaozong
    2023, 52(5):  769-779.  doi:10.11947/j.AGCS.2023.20220050
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    China's first L-band differential interferometric SAR satellite, also named as Lutan-1 (LT-1), is an interferometric satellite constellation using the L frequency full-polarization payload. LT-1 consists of two identical satellites. It uses the differential interferometric technology to conduct the deformation monitoring task for the specified area. In this paper, we research the deformation monitoring requirements and the satellite observing capacity and provide the deformation product classification. The first is the deformation field (DF) product generated using the two calibrated single look complex (SLC) images covering the identical area. The second is the deformation velocity field (DVF) product generated using multiple calibrated SLC images covering the identical area. The third is the multi-temporal deformation (MTD) product produced using the multi-temporal InSAR (MTInSAR) method. Taking the Sentinel-1 data distributed over Yungang District of Datong City, Shanxi Province as an example, we show and analyze the contents of the DF, DVF, and MTD products, and preliminarily explains the characteristics and results of the products. The product system is hoped to provide reference to the operational product generation.
    Self-calibration of Zhurong Mars rover's stereo vision system
    ZHANG Shuo, WEN Bo, ZHANG Jianli, QI Chen, PENG Song, LIU Shaochuang, JIA Yang, YAN Yongzhe, MA Youqing, YANG Huan, LI Hao, WU Yunjia, XIE Wanrong
    2023, 52(5):  780-788.  doi:10.11947/j.AGCS.2023.20210710
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    Zhurong is the first rover of China to detect the Martian surface successfully. It is necessary to carry out self-calibration of the stereo vision system in order to ensure the accurate implementation of the teleoperation mission of Zhurong Rover. The combined adjustment self-calibration model with stereo constraint and mast mechanism motion constraint is proposed. Simulated experiments show that the proposed method has high visual positioning accuracy. In real experiments on Mars, the average error in the obtained check points is 12.3 mm. This effectively ensures the accurate completion of the teleoperation mission of the Zhurong rover.
    A spatial consistency-based point cloud registration method for the same platform
    ZHANG Guangyun, HAN Yi, ZHANG Rongting, LI Mingfeng, JI Wenlai
    2023, 52(5):  789-797.  doi:10.11947/j.AGCS.2023.20220262
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    The feature-based point cloud registration establishes the correspondence by using the feature descriptor. However, due to the influence of noise and repetitive structure, there will inevitably be a large number of mismatches, resulting in a fall in registration accuracy. In this paper, a spatial consistency-based registration (SCR) method was developed for the point cloud from the same platform. SCR makes full advantage of geometric information between discrete points to improve the point cloud registration accuracy. The graph model of the point cloud that is collected by the same platform is constructed by increasing the number of candidates, and an optimization of reweight random walks matching (RRWM) was proposed to obtain the optimal result. The point cloud registration was built using the hypothesis-and-verify approach. Comprehensive experiments demonstrate that the proposed SCR algorithm is effective in registration methods.
    Dual-channel parallel hybrid convolutional neural networks based classification method for high-resolution remote sensing image
    GU Xiaohu, LI Zhengjun, MIAO Jianhao, LI Xinghua, SHEN Huanfeng
    2023, 52(5):  798-807.  doi:10.11947/j.AGCS.2023.20220163
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    High spatial resolution remote sensing images have rich spatial detail information and multi-spectral information. Previous studies have shown that two-dimensional convolutional neural networks (CNN) are suitable for extracting spatial information, while three-dimensional CNN are more suitable for extracting spectral information. In order to make better use of spatio-spectral information, this paper innovatively proposes a dual-channel parallel hybrid convolutional neural networks (DPHCNN), which fully combines the advantages of two-dimensional and three-dimensional CNN in spatio-spectral information extraction. Simultaneously, the hybrid attention mechanism and multi-scale convolution are introduced to enhance the extraction ability of spatial detail features to achieve accurate classification of high-resolution images. In the experiment, the GF-2 image dataset was used for verification. Compared with state-of-the-art deep learning classification methods, the DPHCNN method proposed in this paper not only has the highest classification accuracy and better classification efficiency but maintains the highest robustness in multi-temporal images classification, which has more advantages in comprehensive evaluation.
    SER-UNet algorithm for building extraction from high-resolution remote sensing image combined with multipath
    HU Minghong, LI Jiatian, YAO Yanji, A Xiaohui, LU Mei, LI Wen
    2023, 52(5):  808-817.  doi:10.11947/j.AGCS.2023.20210691
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    Aiming at the problems of inaccurate edges and loss of small buildings in the extracted buildings due to the inability of deep convolution to take into account global features and local features, the SER-UNet algorithm is proposed based on attention mechanism and skip connection. SER-UNet algorithm couples SE_ResNet and max pooling layers in the encoder stage, and the SE_ResNet structure and deconvolution are used in the decoder stage. The feature map is output after fusing the shallow features extracted by the encoder and the deep features extracted by the decoder through skip connections. In order to analyze the effectiveness of the method, the SER-UNet is used to replace the feature extraction structure in the original network in the parallel multi-path feature extraction stage of the MAP-Net network. Finally, the method proposed is experimentally evaluated on the WHU dataset and the Inria dataset, and the IoU and precision reach 91.46%, 82.61% and 95.67%, 92.75%, compared with UNet, PSPNet, ResNet101, and MAP-Net Networks, the IoU is increased by 0.49%, 0.14%, 1.89%, and 1.57%, and the precision is increased by 0.14%, 1.06%, 2.42% and 1.09%, respectively. To further analyze the validity of the SER-UNet algorithm, the edge integrity and small extraction verification IoU and precision reached 85.32% and 94.13% on the AerialImage dataset. The experiment results show that the MAP-Net parallel multipath network combined with SER-UNet algorithm shows good generalization ability. In addition, the SER-UNet algorithm can be effectively embedded in PSPNet, ResNet101, HRNetv2 and other Networks to improve the ability of Network feature representation.
    Cartography and Geoinformation
    A causal graph convolutional network considering missing values for spatio-temporal prediction
    WANG Peixiao, ZHANG Tong, NIE Shichao, YANG Jinxuan, WANG Tianjiao
    2023, 52(5):  818-830.  doi:10.11947/j.AGCS.2023.20220021
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    Spatio-temporal prediction is one of the basic research topics of geographic spatio-temporal big data mining. There are many attempts to predict spatio-temporal state of unknown systems using various deep learning algorithms. However, most existing prediction models are only tested on spatio-temporal data assuming no missing data entries, ignoring the impact of missing values on the prediction results. In the actual scenarios, data missing is an inevitable problem due to sensor or network transmission failures. Therefore, we propose a novel causal graph convolutional network considering missing values (Causal-GCNM) for spatio-temporal prediction. The proposed model can automatically capture missing patterns in the spatio-temporal data, enabling the Causal-GCNM model to directly complete the spatio-temporal prediction task without additional interpolation. The proposed model was validated on three real spatio-temporal datasets (traffic flow dataset, PM2.5 monitoring dataset, and temperature monitoring dataset). Experimental results show that the Causal-GCNM model has good prediction performance under four missing scenarios (20% random missing, 20% block missing, 40% random missing, 40% block missing), and outperforms ten existing baseline methods in terms of prediction accuracy and computational efficiency.
    A cellular automata model incorporating geographical condition-driven effects and graph convolutional network for land use evolution simulation
    ZHAO Bingbing, TAN Xiaoyong, YANG Xuexi, SHI Yan, DENG Min
    2023, 52(5):  831-842.  doi:10.11947/j.AGCS.2023.20220145
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    This paper proposes a cellular automata model for land use evolution that integrates graph convolutional neural network and geographical condition-driven effects, in view of the fact that existing land use evolution modeling methods are limited by Euclidean spatial constraints and thus can not effectively model the emerging phenomenon of land with no historical data in the spatial neighborhood. Firstly, the spatial neighborhood multiscale effect of the cell is modeled by introducing a dilated convolution layer. Then the geographic condition similarity network is constructed based on the geographic condition vector of the cell, applying the graph convolutional neural network to extract the regional potential features in it. Finally, land use evolution is simulated by fusing the artificial neural network and the cellular automata. This paper improves the ability of the model to the emerging phenomenon of land with no historical data in the spatial neighborhood by modeling the geographical condition-driven effects, and successfully achieves effective simulation of urban land use evolution. The experiments were conducted in three research regions including Xuanwu district of Nanjing, Furong district of Changsha, and Nanchang. The results show that our method improves in overall accuracy (OA), Kappa coefficient, and figure of merit(FoM), allowing for more accurate modeling of land use evolution than the classical land use evolution modeling method considering only Euclidean spatial neighborhood features.
    A dynamic weighted model for semantic similarity measurement between geographic feature categories
    TAN Yongbin, GAO Lingling, LI Lin, CHENG Penggen, WANG Hong, LI Xiaolong, CHEN Cheng
    2023, 52(5):  843-851.  doi:10.11947/j.AGCS.2023.20220330
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    Semantic similarity is a key technology to solve the problem of semantic heterogeneity of geographic feature categories, and plays an important role in geographic data sharing and exchange applications. In this article, a semantic similarity calculation model of geographic feature categories based on dynamic weights is proposed to represent the difference in importance of semantic properties among geographic feature categories for the need of fundamental geographical domain application. TF-IDF algorithm is introduced and the particularity of the property value is used to calculate the dynamic weight of a semantic property. And the similarity model between a pair of complex properties is proposed, and then the final similarity between geographic feature categories is calculated. Finally, 200 pairs of samples are selected from the basic geographic element categories to calculate the semantic similarity, and compared with other similarity calculation models. The experimental results show that the model proposed in this article can effectively reflect the importance difference of semantic properties and obtain more reasonable semantic similarity between geographic feature categories.
    Residential area selection method from the perspective of complex network
    Lü Zheng, SUN Qun, MA Jingzhen, WEN Bowei
    2023, 52(5):  852-862.  doi:10.11947/j.AGCS.2023.20220267
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    Multi-feature collaborative generalization is an important development direction of cartographic generalization. Aiming at the problem that the current residential area selection methods don't fully utilize the geographical correlation between the road network and residential areas, we integrate residential areas and road network as a whole, and propose the residential area selection method from the perspective of complex network. First, the measurement information, attribute information and topology information are integrated to construct a weighted residential area network with residential areas as nodes and traffic accessibility as edges. Then, the attraction ability and traffic flow control ability of the target residential area in the local network are evaluated, and the comprehensive importance is obtained by weighted summation. Finally, the residential areas are iteratively selected by Delaunay triangulation with distance constraints. The experiments indicate that the method can take into account the density characteristics of residential areas and network characteristics, and better maintain the geographical correlation between the road network and residential areas.
    Summary of PhD Thesis
    Monitoring soil erosion and modeling sediment transport in Small Loess Catchments based on DEM
    DAI Wen
    2023, 52(5):  863-863.  doi:10.11947/j.AGCS.2023.20210522
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    Visual/INS/LiDAR integration for high-precision pose estimation in complex urban environment
    LIN Xiaohu
    2023, 52(5):  864-864.  doi:10.11947/j.AGCS.2023.20210525
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    Reaching local vertical datum using global geopotential model and GPS/Leveling data
    HE Lin
    2023, 52(5):  865-865.  doi:10.11947/j.AGCS.2023.20210535
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    Research on digital watermarking for vector maps to maintain data availability
    XI Xu
    2023, 52(5):  866-866.  doi:10.11947/j.AGCS.2023.20210538
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    Research and application of key technologies for intelligent supervisory of filling and rolling construction quality
    ZHANG Wen
    2023, 52(5):  867-867.  doi:10.11947/j.AGCS.2023.20210545
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    Study and methodology for real-time ionosphere modeling
    CHEN Jun
    2023, 52(5):  868-868.  doi:10.11947/j.AGCS.2023.20210566
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    Research on high-precision alignment control method for extra-long immersed tunnels
    LI Guanqing
    2023, 52(5):  869-869.  doi:10.11947/j.AGCS.2023.20210582
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    A research on hierarchical indoor and outdoor scene understanding method based on 3D point clouds
    YANG Juntao
    2023, 52(5):  870-870.  doi:10.11947/j.AGCS.2023.20210586
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