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    Acta Geodaetica et Cartographica Sinica 2022 Vol.51
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    On geospatial information science in the era of IoE
    LI Deren, XU Xiaodi, SHAO Zhenfeng
    Acta Geodaetica et Cartographica Sinica    2022, 51 (1): 1-8.   DOI: 10.11947/j.AGCS.2022.20210564
    Abstract （1443）   HTML （156）    PDF（pc） （6016KB）（1374）       Save
    With the development of new technologies such as 5G/6G, cloud computing, internet of things and artificial intelligence, we have entered a new era of Internet of Everything(IoE). Five characteristics of geospatial information technology in the era of IoE discussed in this paper as followed:the development of satellite positioning technology has changed from GNSS and ground measurements to PNT system with wider service coverage; remote sensing technology has moved from isolated satellite observation to space-air-ground wireless sensor network; geographic information service moves from map database to true 3D realistic scene and digital twin; 3S integration develops from mobile measurement to intelligent robot service; research scope of geospatial information science changes from earth observation to internet of thing monitoring and perception of human activities in order to reveal the relationship between human and environment. On this basis, this paper further analyzes the challenges in the new era, and puts forward three major scientific issues to be solved:How can geographic information products meet the needs of people and robots at the same time? What are the mechanism and bottleneck of remote sensing image interpretation? How to use spatiotemporal big data to mine the relationship between man and nature and realize the leap from spatial perception to spatial cognition? Geospatial information science must and can make greater contributions to the digital earth and intelligent society in the era of IoE!
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    OD/SINS adaptive integrated navigation method with non-holonomic constraints
    LIU Wanke, NONG Qi, TAO Xianlu, ZHU Feng, HU Jie
    Acta Geodaetica et Cartographica Sinica    2022, 51 (1): 9-17.   DOI: 10.11947/j.AGCS.2022.20210122
    Abstract （1270）   HTML （50）    PDF（pc） （8583KB）（704）       Save
    In the ground vehicle integrated navigation GNSS/OD/SINS, the global navigation satellite system (GNSS) signal is susceptible to environmental interference or even interruption. The non-holonomic constraint (NHC) is applied to the odometer (OD)/strap-down inertial navigation system (SINS) combination, which can effectively suppress the error divergence of the integrated navigation system during the GNSS signal interruption. Usually, NHC's noise setting is based on a fixed empirical value. However, the trajectory of the vehicle is complex and changeable during actual movement, and its motion state cannot fully satisfy the NHC premises and assumptions. The noise given by experience cannot accurately reflect the actual vehicle motion. Therefore, this paper analyzes the relationship between NHC noise and vehicle motion state, and constructs a NHC noise adaptive method based on vehicle motion state. Validation of the real-world experiments of the selected scene shows that the result of the noise-adaptive NHC/OD/SINS combined navigation is compared with the fixed-noise NHC/OD/SINS combination, when the GNSS signal is interrupted for 110 s and the vehicle turns continuously, the maximum horizontal position error is reduced by 68.4%; when the GNSS signal is interrupted for 74 seconds and the vehicle is traveling in a straight line, the maximum horizontal position error is reduced by 87.3%; the error divergence of the integrated navigation system during the GNSS interruption can be better suppressed.
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    High-precision indoor positioning based on robust LM visual inertial odometer and pseudosatellite
    YANG Gaochao, WANG Qing, YU Baoguo, LIU Pengfei, LI Shuang
    Acta Geodaetica et Cartographica Sinica    2022, 51 (1): 18-30.   DOI: 10.11947/j.AGCS.2022.20200251
    Abstract （787）   HTML （25）    PDF（pc） （6373KB）（396）       Save
    Visual inertial odometer (VIO) and pseudo-satellite have been widely used in positioning indoors, but in practical applications, both approaches have their own limitations. The visual odometer depends on the actual positioning environments. Gross errors occur in environments with obvious changes in depth of field and uneven illumination, and errors will inevitably accumulate over time. However, relatively high-precision pose measurements can be obtained between adjacent frames. Due to the influence of indoor multipath, the accuracy and reliability of pseudolite indoor positioning are difficult to guarantee. To increase the reliability and stability of indoor positioning, based on the robust LM nonlinear optimization theory, this study mainly investigate indoor high-precision positioning technology approach of integrating high-precision pose measurements of VIO between adjacent frame and pseudolite. The algorithm can not only resist gross errors, but also reduce the influence of unreasonable weight settings among different sensors. Finally, the high-precision dynamic capture equipment built in the indoor environment is used to verify the proposed method. The experimental results show that the method can eliminate the cumulative error of the visual inertial odometer without relying on the loopback, and effectively improve the indoor positioning accuracy and reliability. Compared with the VIO, the positioning accuracy is improved by 59.0% and 77.5% respectively after using the improved LM algorithm for scenes 1 and 2.
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    A layered constant gradient acoustic ray tracing underwater positioning algorithm considering round-trip acoustic path
    YAN Fengchi, WANG Zhenjie, ZHAO Shuang, NIE Zhixi, SUN Zhen, LI Weijia
    Acta Geodaetica et Cartographica Sinica    2022, 51 (1): 31-40.   DOI: 10.11947/j.AGCS.2022.20210234
    Abstract （1473）   HTML （25）    PDF（pc） （4240KB）（371）       Save
    The acoustic ray tracing algorithm is typically adopted for high precision underwater positioning. However, the traditional acoustic ray tracing method is usually based on the one-way acoustic propagation path without the consideration of the displacement of shipborne transducer during the process of acoustic signal propagation. Therefore, the systematic deviation will be introduced in the positioning for seafloor transponder, which will limit the positioning accuracy of seafloor points. To solve this problem, a layered constant gradient acoustic ray tracing underwater positioning algorithm considering round-trip acoustic path is proposed in this paper. Combined with the actual propagation path of underwater acoustic signal, the round-trip acoustic path underwater positioning model is established according to the position of the transducer at the time of acoustic signal emission and reception, and the layered constant gradient acoustic ray tracing algorithm is applied to solve the foresaid problem. Experiments were carried out on the two observation patterns of circular tracing line and cross lines. The results show that the proposed method can effectively improve the underwater positioning accuracy on the premise of ensuring the calculation efficiency.
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    Rigorous modification model of upward continuation and its applications on the downward continuation of gravity anomaly
    HUANG Motao, DENG Kailiang, WU Taiqi, OUYANG Yongzhong, CHEN Xin, LIU Min, WANG Xu
    Acta Geodaetica et Cartographica Sinica    2022, 51 (1): 41-52.   DOI: 10.11947/j.AGCS.2022.20200547
    Abstract （677）   HTML （13）    PDF（pc） （3968KB）（332）       Save
    The global integral model of upward continuation for gravity anomaly is often used in the data quality assessment for airborne gravity measurement and the iterative solution of downward continuation. In order to eliminate the singularity of the integral kernel function, we have to make a remove-restore transformation to the integral model based on an equation of integral identity. And at the same time, the global integral domain has to be divided into two parts of near and far zones. During this processing, the deviation of identical formula caused by the transformation of integral domain from global to local integration is often ignored in the traditional modified method, which leads to unnecessary model errors and ultimately affects the reliability of upward continuation solution, and even affects the stability of iterative solution of downward continuation. In response to this problem, some analysis and research have been made on the integral model modification of upward continuation and its application of downward continuation for gravity anomaly in this paper. Based on the measured data situation and the applied condition of the integral identity, a set of step-by-step modified formulas of the upward continuation integral model are derived, and a correction formula is proposed to compensate the omission of the traditional modified model. Finally, the rigorous modified model is applied to the iterative solution of downward continuation for gravity anomaly. The ultra-high-degree geopotential model EGM2008 is used as a standard potential field to carry out a set of numerical calculation test, and the calculated accuracy of step-by-step modified models of the upward continuation and the applied effect in the iterative solution of downward continuation for gravity anomaly are estimated and evaluated separately. It proves the necessity and effectiveness of adopting the rigorous modified model.
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    An analytical method for bathymetry inversion using vertical gravity gradient anomaly
    XU Huan, YU Jinhai, AN Bang, WAN Xiaoyun
    Acta Geodaetica et Cartographica Sinica    2022, 51 (1): 53-62.   DOI: 10.11947/j.AGCS.2022.20200578
    Abstract （773）   HTML （15）    PDF（pc） （3878KB）（263）       Save
    At present, the main principle of the seafloor topography inversion method is to fit the most appropriate linear relationship between topography and gravity or gravity gradient. However, different topography will have different linear relationships. In order to overcome the constraint of uncertainty, this paper firstly derives the expression of vertical gravity gradient generated by cubic prism. Then, by gridding the research sea area, a functional relationship between vertical gravity gradient (VGG) and sea depth is established, i.e. the observation equations of sea depth. On the basis of which, it is that the observation equations have strong anti-error interference properties through simulation calculation. Because the observation equations are affected by the seamounts outside the study area (divided into boundary effects and far area effects), it is necessary to propose corresponding mathematical methods to deal with these effects. This paper proposes to expand the research sea area to obtain an expanded area, and then study the observation equations on the expanded sea. At this time, in order to avoid the singularity of the observation equations, a regularization method is introduced to solve the expanded observation equations and cut out the sea depth in the study area. Simulation experiments show that after using the regularization method, the root-mean-square error of the inverted sea depth is only 0.48 m. Finally, this paper inverts an actual seafloor topography of the South China Sea, and the results are compared with the 289 ship sounding data. The root-mean-square error of the inversion results can reach 109 m.
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    Pre-seismic anomalies and co-seismic gravity changes of 2011 Tohoku-Oki earthquake ( M w 9.0) detected by superconducting gravity data
    DONG Jie, ZHANG Zeyu, WEN Hanjiang, SUN Wenke
    Acta Geodaetica et Cartographica Sinica    2022, 51 (1): 63-70.   DOI: 10.11947/j.AGCS.2022.20210014
    Abstract （679）   HTML （21）    PDF（pc） （4555KB）（322）       Save
    High-precision superconducting gravity data had been widely used in the study of geodynamics. The detection of the pre-seismic anomalies and co-seismic gravity changes caused by a huge earthquake is helpful to the study of focal mechanism and early warning. Meanwhile, the co-seismic observations can be used in the inversion of fault slip model. We study the gravity changes caused by the Tohoku-Oki earthquake ( M w 9.0) using the second sampling data in March 2011 of 7 Superconducting Stations in Japan, China and Europe. We obtained the corrected gravity changes by the preprocessing of tide, air-pressure and drift correction, et al. Comparing the 2861 M b ≥ 4 earthquakes near the Japan island at the same period and analyzing the filtered gravity changes, we can exclude the influence of non-main earthquakes and find the obvious pre-seismic anomalies at frequencies 0.12 Hz ≤ f ≤ 0.18 Hz. The pre-seismic anomalies occurred 89 h before the earthquake for all the stations. The maximum amplitude of pre-seismic anomalies reaches 28×10 -8 m/s 2 at Medicina. Moreover, the theoretical co-seismic gravity changes simulated by the spherical dislocation theory and the CMT solution, are very close to the observed values of superconducting gravimeters. The absolute values of co-seismic gravity changes are inversely proportional to the epicenter distances.The observations at near-field are closer to the theoretical calculations than that at far-field, and the former can be used as the constraints for fault inversion.
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    Non-ergodic approximation method for intersections of airborne gravity survey network
    QU Jinhong, JIANG Zuoxi, ZHOU Xihua, LUO Feng, LI Fang
    Acta Geodaetica et Cartographica Sinica    2022, 51 (1): 71-79.   DOI: 10.11947/j.AGCS.2022.20210037
    Abstract （606）   HTML （5）    PDF（pc） （1575KB）（135）       Save
    The gravity difference at the intersections of the airborne gravity survey network is an important basis for objectively evaluating the measurement quality of the survey lines, and it is alsoan important way to adjust the level difference of the gravity field between the survey lines. With the enlargement and irregularity of the survey network, it is very important to search the intersections accurately and quickly. Existing methods all traverse one by one after narrowing the range of intersections, which cannot guarantee that all intersections can be searched quickly and accurately. The non-ergodic approximation method proposed in this paper is to perform iterative approximation through a combination of fast approximation and fine-tuning approximation, avoiding one-by-one traversal and directly approaching the intersections quickly. Experimental results show that this method is not only suitable for continuous and uniform conventional networks, but also suitable for irregular and unconventional networks. The search speed is 3~4 orders of magnitude higher than the existing methods, and it is also far superior than the famous Canadian commercial geophysical software of Oasis Montaj.
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    Adaptive Kalman filter method with colored noise for fiber optic gyroscope random drift
    JIN Kaidi, CHAI Hongzhou, SU Chuhan, XIANG Minzhi
    Acta Geodaetica et Cartographica Sinica    2022, 51 (1): 80-86.   DOI: 10.11947/j.AGCS.2022.20200614
    Abstract （487）   HTML （16）    PDF（pc） （2729KB）（324）       Save
    Random noise reduces the accuracy of output seriously as an important part of fiber optic gyroscope (FOG) error. Accurate modeling and compensation of random noise is an effective way to improve the accuracy of FOG. To solve the problem that FOG random noise is complicated and to accurately analyze difficultly, and the colored noise in the ARIMA model is modeled as the state equation by using the state expansion method, the Harvey algorithm is reconstruct to whiten colored noise. At the same time, considering the uncertainty of priori noise and the coupling between states and noise caused by online update of ARIMA model, variational Bayesian adaptive filter (VBAKF) is used to correct the state and measurement noise. Experiments show that the Harvey method reduces the random noise sequence variance by 40% compared with the traditional filtering modeling method. The Harvey method combined with VBAKF reduces the sequence variance by 54%; VBAKF can better estimate the measurement noise than the dynamic Allan variance. Method in this paper can effectively suppress the effects of colored noise and random model inaccuracy in the random noise Kalman filter, and improve the accuracy of random error compensation.
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    Real time recognition method of weak signal in space debris laser ranging
    MA Tianming, ZHAO Chunmei, HE Zhengbin, ZHANG Haoyue
    Acta Geodaetica et Cartographica Sinica    2022, 51 (1): 87-94.   DOI: 10.11947/j.AGCS.2022.20200527
    Abstract （540）   HTML （11）    PDF（pc） （1703KB）（194）       Save
    In view of the high false detection rate of traditional secondary filtering algorithm in real-time recognition of weak signal from space debris laser ranging, based on the characteristics of the time correlation of echo signal from space debris laser ranging, a method combining primary filtering and linear fitting is proposed, by which the search cost and recognition accuracy of real-time identification of weak signal is considered and the real-time identification of weak signal from space debris laser ranging is realized. The algorithm was verified using the actual data of space debris laser ranging, and the results showed that the weak signal of space debris can be quickly and accurately extracted by the real-time recognition algorithm for weak signal of laser ranging proposed in this paper, and the false detection rate was decreased from 5.72% to 0.12%, the rate of missed inspection was decreased from 0.77% to 0.34%, which is of great significance to improve the success rate of space debris detection.
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    Semantic similarity measurement for building polygon aggregation in multi-scale map space
    GAO Xiaorong, YAN Haowen, LU Xiaomin
    Acta Geodaetica et Cartographica Sinica    2022, 51 (1): 95-103.   DOI: 10.11947/j.AGCS.2022.20210074
    Abstract （770）   HTML （62）    PDF（pc） （4269KB）（522）       Save
    Map generalization is a process of spatial similarity transformation in multi-scale map spaces. Cartographers generalize under the guidance of the similarity principle; at the same time, map readers form mental maps and reconstruct the real world from maps containing similarity. Thus, it is of great significance to study and measure the similarity relations with respect to the scale reduces in multi-scale map spaces. However, due to the poor computability of similarity and the purpose of its computation is to reveal deeper information, there are few achievements on similarity relations especially semantic relations in multi-scale map spaces. To solve this problem, semantic similarities in city block aggregation (from approximately 1:1750 to 1:14 000) under the constraint of semantic functional units are computed, and the method for measuring the semantic similarity is the matching-distance model based on ontology and set theory. By the experiment of different city block generalization, the semantic similarity values at key scales were obtained and the results were analyzed and evaluated. The experimental results have shown that the building aggregation under the constraint of semantic functional units is in accordance with map readers' cognitive needs. The method described in this paper is helpful for map to play a better role as a carrier of information transmission.
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    Hierarchical evolution model and coding calculation of three-dimensional Hilbert curve
    WU Yuhao, CAO Xuefeng, YU Anzhu, SUN Wanzhong
    Acta Geodaetica et Cartographica Sinica    2022, 51 (1): 104-114.   DOI: 10.11947/j.AGCS.2022.20200241
    Abstract （716）   HTML （32）    PDF（pc） （2191KB）（323）       Save
    The coding calculation of grid cells is the core of the discrete global grid system, which supports efficient calculation of indexing and analysis. Hilbert curve has the characteristics of high clustering and strong continuity, and is an important tool for global discrete grid coding. The lattice element coding using Hilbert curve realizes the coordinate equivalent dimensionality reduction expression, but the research on the basic theoretical problems of grid coding still not complete. In this paper, the hierarchical evolution relationship of the three-dimensional Hilbert curve in the octree three-dimensional grid is used as a breakthrough. The state matrix and the evolution matrix are used to construct a hierarchical evolution model, and then the calculation methods of Cartesian coordinates to Hilbert codes and adjacent grid Hilbert codes are designed respectively. Compared with the existing algorithms, the algorithm in this paper is based on a hierarchical evolution model, which avoids cumbersome iteration steps and conversion steps, and the algorithm flow is simple and straightforward. The experimental results show that the calculation efficiency of Cartesian coordinates to Hilbert codes in this paper is "7%~23%" higher than that of the iterative algorithm, and the calculation efficiency of neighbor grid elements Hilbert codes is 4.0~4.5 times higher than that of the conversion algorithm.
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    A hybrid SfM method based on partition optimization
    XU Biao, DONG Youqiang, ZHANG Li, SUN Yushan, LIU Yuxuan, ZHA Bing, HAN Xiaoxia
    Acta Geodaetica et Cartographica Sinica    2022, 51 (1): 115-126.   DOI: 10.11947/j.AGCS.2021.20210105
    Abstract （718）   HTML （26）    PDF（pc） （11754KB）（470）       Save
    Aiming at solving the problem of sparse 3D reconstruction of large-scale unordered images, this paper proposes a robust, efficient, and easy-to-parallel hybrid SfM method based on partition optimization. Firstly, the SIFT algorithm is used for image matching, and image partitioning is completed using image correlation scores calculated from the matching results without other auxiliary information such as GPS/INS. Secondly, an improved incremental SfM method is applied to achieve rapid reconstruction in each partition, and a number of standards are introduced to automatically eliminate the unreliable partitions and re-divide the images in these partitions into other partitions to achieve dynamic adjustment. Finally, a robust and high-precision partition fusion algorithm is proposed to realize accurate fusion of camera parameters, image posture, and 3D information of the scene. The experimental results of multiple challenging data sets of different scales, different image types, and different scenes show that our proposed hybrid SfM method has good robustness to different data sets and dramatically improves efficiency while maintaining high precision,which especially suitable for large-scale image sets.
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    A RFM adjustment method for satellite remote sensing image with Fourier compensation
    YU Junpeng, WU Weidong, SUN Jiaming, MAN Yiyun, SHEN Gang
    Acta Geodaetica et Cartographica Sinica    2022, 51 (1): 127-134.   DOI: 10.11947/j.AGCS.2021.20200429
    Abstract （595）   HTML （18）    PDF（pc） （3390KB）（174）       Save
    The geometric distortion of satellite optical remote sensing images is an important factor that restricts its positioning accuracy. It is difficult to completely eliminate the complex distortion of the image using the common system error compensation model. Based on the rational function model adjustment scheme, and according to the approximation characteristics of the Fourier series, this paper proposes to replace the general polynomial with a binary Fourier polynomial as the system error compensation term to adapt to any form of distortion that meets the continuous condition. Simulation and actual data adjustment test results show that the new method can effectively compensate the image positioning system errors caused by the inaccurate internal and external orientation elements of the image and different magnitudes of distortion. Given enough ground control points, the positioning accuracy of the RFM adjustment using the third-order Fourier compensation term is significantly better than that of the traditional method using general polynomial compensation terms. The positioning accuracy of the plane and elevation after the adjustment of the SPOT-5 different track stereo image can reach 3.34 m and 2.48 m, the plane and elevation positioning accuracy of QuickBird co-track stereo image pair adjustment reached 0.77 m and 0.54 m, both reaching the sub-pixel accuracy level. The binary Fourier polynomial can be used as a general image system error compensation model, which can be further applied to the distortion correction process of aerial and close-range images.
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    Multi-path RSU network method for high-resolution remote sensing image building extraction
    ZHANG Yuxin, YAN Qingsong, DENG Fei
    Acta Geodaetica et Cartographica Sinica    2022, 51 (1): 135-144.   DOI: 10.11947/j.AGCS.2021.20200508
    Abstract （655）   HTML （60）    PDF（pc） （3371KB）（422）       Save
    Inaccurate boundaries and holes are two major problems when extracting buildings from high-resolution remote sensing images by a convolution network. To solve these problems, we proposed the MPRSU-Net (multi-path residual U-block network), which is based on the RSU (residual U-block). The RSU is able to fuse local features and multi-scale features, with the help of the encoder-decoder structure and the residual connection. However, a single RSU is not enough to gather enough information, MPRSU-Net parallels RSU blocks of different scales by the multi-path structure and exchanges information among these blocks to further enhance the feature aggregation efficiency. Experimental results showed that the MPRSU-Net achieved 95.65%,88.63% precision, and 91.17%,79.31% IoU on 0.3 m resolution WHU and Inria building datasets, which showed the effectiveness of the proposed method. In addition, compared with the U 2 Net, MPRSU-Net is much lighter in computation and reduces the amount of model parameters by 68.63%, demonstrating that the method has some application value.
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    River waterbody extraction from SAR images based on speckle reduction and multi-resolution topological analysis
    YANG Yun, LI Yu, ZHAO Quanhua
    Acta Geodaetica et Cartographica Sinica    2022, 51 (1): 145-158.   DOI: 10.11947/j.AGCS.2022.20190395
    Abstract （604）   HTML （20）    PDF（pc） （16924KB）（472）       Save
    Aiming at the discontinuity of river waterbody extraction from high-resolution SAR images caused by speckle noise and building occlusion, a river waterbody extraction method combining adaptive speckle reduction and multi-resolution topological analysis is proposed. Firstly, the Beta metric is introduced into the speckle reduction anisotropic diffusion to achieve adaptive speckle filtering of SAR images. Secondly, the local threshold segmentation and connected region identification are used to quickly extract river waterbody segments from the denoised image. Then, a Gaussian pyramid is constructed with the smallest circumscribed convex polygon of the river waterbody segments as the object, and multi-resolution topological analysis is performed to obtain the information of river discontinuities. Finally, the regional growth strategy is used to distinguish the discontinuities layer by layer to realize the automatic connection of adjacent river waterbody segments. The proposed method is verified by TerraSAR-X and GF-3 high-score SAR images. The results show that the proposed method can effectively extract complete river waterbody. The effectiveness and robustness of the proposed method are verified by the qualitative and quantitative evaluation of multiple SAR images.
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    Review of GNSS landslide monitoring and early warning
    ZHANG Qin, BAI Zhengwei, HUANG Guanwen, DU Yuan, WANG Duo
    Acta Geodaetica et Cartographica Sinica    2022, 51 (10): 1985-2000.   DOI: 10.11947/j.AGCS.2022.20220299
    Abstract （810）   HTML （125）    PDF（pc） （5536KB）（1182）       Save
    Landslides, widely happening across the world, have a severely negative impact on human activities and people's residential security. GNSS has been widely used in landslide disaster monitoring and warning, but there are still many technical bottlenecks in complex scenario monitoring and warning. First of all, this paper reviews the current research on landslip reduction technologies by GNSS such as monitoring receiver, high-precision positioning and multi-source heterogeneous data fusion monitoring, and lays special stress on analyzing the advantages, applicable range and latent problems of landslide-monitoring technologies of every kind. Furthermore, the technical methods suitable for releasing warning by GNSS are introduced from landslide displacement prediction, the prediction of sliding time and the implementation of early warning. Lastly, a comprehensive analysis on the challenges brought about by GNSS's real-time monitoring in complex scenarios is conducted, and some ideas are proposed for the future development and research of technologies monitoring and warning landslides through GNSS.
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    Recent progress in landslide monitoring with InSAR
    ZHU Jianjun, HU Jun, LI Zhiwei, SUN Qian, ZHENG Wanji
    Acta Geodaetica et Cartographica Sinica    2022, 51 (10): 2001-2019.   DOI: 10.11947/j.AGCS.2022.20220294
    Abstract （747）   HTML （85）    PDF（pc） （23492KB）（1530）       Save
    The development of InSAR technique and the tremendous amount of SAR data have made InSAR the fundamental tool in landslide monitoring.This paper begins with the data selection, the effects of different datasets and scenes in landslide monitoring by InSAR are introduced. We analyze the main limitations affecting the accuracy of landslide monitoring by InSAR, and demonstrate the corresponding solutions. Subsequently, the methods in retrieving landslide-induced 3D displacement using InSAR are then classified, and their advantages, disadvantages, and application scopes are also analyzed. Finally, the limitations in landslide monitoring with InSAR, the corresponding solutions, and future development trends are discussed.
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    Application status and prospect of aerial remote sensing technology for geohazards
    XU Qiang, GUO Chen, DONG Xiujun
    Acta Geodaetica et Cartographica Sinica    2022, 51 (10): 2020-2033.   DOI: 10.11947/j.AGCS.2022.20220302
    Abstract （547）   HTML （89）    PDF（pc） （24455KB）（1181）       Save
    Geoharzards occur frequently in China, and the losses are especially serious. A number of catastrophic geohazards have occurred in recent years, which indicate that the prevention of geohazard in mountainous areas covered by high vegetation and in some inaccessible areas restricted by topographic conditions is still a difficult problem for traditional methodology. Aerial remote sensing technology can quickly and efficiently reveal the spatial distribution characteristics and spatial and temporal evolution rules of geoharzard, which has played an important role in the field of geoharzard prevention. Based on the brief introduction of the airborne remote sensing technology, platform and sensor, this paper systematically summarizes the research and application of airborne remote sensing at home and abroad in the geoharzard identification, investigation and evaluation, long-term monitoring, emergency response, virtual reality displayed. Analyzes the challenges faced by the application of airborne remote sensing in geoharzard, and looks forward to the development of the application of airborne remote sensing in geoharzard research trend.
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    Multi-kernel support vector machine considering sample optimization selection for analysis and evaluation of landslide disaster susceptibility
    LIU Jiping, LIANG Enjie, XU Shenghua, LIU Mengmeng, WANG Yong, ZHANG Fuhao, LUO An
    Acta Geodaetica et Cartographica Sinica    2022, 51 (10): 2034-2045.   DOI: 10.11947/j.AGCS.2022.20220326
    Abstract （316）   HTML （39）    PDF（pc） （5632KB）（344）       Save
    The analysis and evaluation of landslide disaster susceptibility is of great significance to the prevention and management of geological disasters. In view of the sample selection strategy and the unreasonable multi-feature mapping in single-kernel vector machine, this paper proposes the landslide susceptibility analysis and evaluation method of multiple kernel support vector machine (MKSVM) considering the sample optimization selection. To ensure sample balance and improve the plausibility of negative samples, using the relative frequency ratio (relative frequency, RF) comprehensively evaluate the importance degree of each state in the influence of landslide disaster susceptibility, the purpose is to realize the reasonable division of each evaluation factor state; Using the deterministic coefficient method (certainty factor, CF) calculates the sensitivity of each state of each evaluation factor, the weighted sum has obtained the landslide disaster susceptibility index of each grid cell, non-landslide disaster points consistent with the number of landslide disaster points were randomly selected in the very low and low landslide disaster prone index as the negative sample data. Then, multi-kernel learning is used to select the SVM optimal kernel function and to linear combine the optimal kernel functions in each feature space to avoid unreasonable mapping of a single kernel function, and it improve the classification accuracy and prediction accuracy of the model. Taking Xiangxi Tujia and Miao Autonomous Prefecture of Hunan province as the research area, MKSVM model of CF sample strategy, single-kernel SVM model of CF sample strategy, MKSVM model of random sample strategy and single-kernel SVM model of random sample strategy were compared analyzed from three aspects of landslide disaster prone zoning map, partition statistics and evaluation model accuracy. The results indicate that the subject operating characteristic curves of the four models (receiver operating characteristic, area under the ROC) (area under curve, AUC) were 0.859,0.809,0.798,0.766, the rationality and validity of the CF sample strategy and the reliability of the MKSVM model are verified.
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    Deep learning identification technology of InSAR significant deformation zone of potential landslide hazard at large scale
    WU Qiong, GE Daqing, YU Junchuan, ZHANG Ling, LI Man, LIU Bin, WANG Yan, MA Yanni, LIU Hongjuan
    Acta Geodaetica et Cartographica Sinica    2022, 51 (10): 2046-2055.   DOI: 10.11947/j.AGCS.2022.20220303
    Abstract （443）   HTML （64）    PDF（pc） （32928KB）（799）       Save
    Comprehensive identification and discovery of potential landslide hazards has become a major practical demand of geological hazard prevention and control in China. At present, the application effect and applicability of the combination of InSAR technology and deep learning for the intelligent identification of geological hazards at large scale are still worthy of further exploration and research, this paper obtained the phase data of surface deformation based on stacking interferometric synthetic aperture radar (Stacking InSAR) technology, used deep learning to identify the location and distribution of the deforming landslide hazards, and determined the boundary of the significant deformation zone of potential landslide hazards. The above technical methods were exploratively applied to test and dynamic update data sets. The average identification precision, recall and F 1 score value of the test data set were 0.69, 0.67 and 0.67, respectively. The identification precision, recall and F 1 score value of the dynamic update data set were 0.85, 0.58 and 0.68, respectively. The results showed that the technical method used in this paper is feasible in the identification of potential landslide hazards in a wide area, and can provide theory and technical support for geological disaster monitoring and early warning.
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    The bedding rock landslide identification in the head area of the Three Gorges Reservoir combined with disaster pregnant mechanism and comprehensive remote sensing method
    HUANG Haifeng, XUE Ronghua, ZHAO Beibei, YI Wu, DENG Yonghuang, DONG Zhihong, LIU Qing, YI Qinglin, ZHANG Guodong
    Acta Geodaetica et Cartographica Sinica    2022, 51 (10): 2056-2068.   DOI: 10.11947/j.AGCS.2022.20220306
    Abstract （288）   HTML （35）    PDF（pc） （32683KB）（482）       Save
    The identification of hidden dangers is an important technical work to realize the transformation of potential geological hazards from post-disaster relief to pre-disaster prevention.This paper proposes a method for identifying the bedding rock landslide based on disaster pregnant mechanism and comprehensive remote sensing detection technology. Firstly, data analysis, remote sensing survey and field survey is used for identifying disaster-pregnant environment and establishing a disaster-pregnant index system; at the same time, typical hazard mode and the identification mark of integrated remote sensing are established. Then, key target areas and suspected hidden dangers of geological disasters are delineated. And geological hazard identification is realized relied on ground detailed assessments and professional identification. By using this set of technical methods, a total of 8 potential catastrophic geohazards have been identified in the work area, of which 5 are potential rockslides with hazard-pregnancy modes but not yet apparently deformed. The results show that this method can make up for the disadvantages of low accuracy or even failure mainly relying on remote sensing change detection. It is especially suitable for hidden and sudden geological hazard identification in areas with steep hills and dense vegetation.
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    Identification of potential landslides in Baihetan Dam area before the impoundment by combining InSAR and UAV survey
    DAI Keren, SHEN Yue, WU Mingtang, FENG Wenkai, DONG Xiujun, ZHUO Guanchen, YI Xiaoyu
    Acta Geodaetica et Cartographica Sinica    2022, 51 (10): 2069-2082.   DOI: 10.11947/j.AGCS.2022.20220305
    Abstract （542）   HTML （51）    PDF（pc） （58296KB）（693）       Save
    Baihetan Dam is located in the high and steep mountain area of southwest China, which is an important part of national project “West to East power transmission” in China. The two banks of the reservoir are highly prone to geological disasters, and the traditional geological disaster investigation means have obvious shortcomings, such as low efficiency, high risk, and unable to cover potential hazards in upper slope. The application of space-borne synthetic aperture radar interferometry (InSAR) and unmanned aerial vehicle (UAV) aerial survey technology for the identification of potential landslides in wide-area is of great significance for identifying potential landslides, understanding their distribution characteristics and mitigating the disaster. In this paper, based on 142 Sentinel-1 satellite images, active slopes with clear displacements were identified on both banks of Baihetan Dam area before impoundment by using sequential InSAR technology. Meanwhile, UAV aerial survey technology was used to verify and analyze the active slopes. According to digital aerial photography products such as DEM, DOM and 3D model, and 32 potential landslides were identified. Combined with the factors of displacement magnitude, displacement area, whether the potential landslides are involved in water and the threating objects, the prevention and control suggestions were given, and a comprehensive and accurate database of potential landslides before impoundment was established. Finally, the advantages, application scope and the effective combination strategy of these two technologies are summarized based on this case. This paper reveals that during the combination of the two technologies on the potential landslides identification in wide area, not only can UAV survey verify the displacement area monitored by InSAR, but also InSAR could improve the flight efficiency of aerial survey. By combining the real-time and historical information, displacement and geological information provided by the two technologies, an efficient comprehensive space-air remote sensing strategy for potential landslides identification in wide dam area can be achieved.
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    Deformation characteristics analysis of the expansive soil slope by integrating of InSAR and SSA techniques: a case study of the South-to-North Water Diversion Project
    ZHU Wu, DOU Hao, YIN Nazheng, CHENG Yiqing, ZHANG Shuangcheng, ZHANG Qin
    Acta Geodaetica et Cartographica Sinica    2022, 51 (10): 2083-2092.   DOI: 10.11947/j.AGCS.2022.20220357
    Abstract （344）   HTML （32）    PDF（pc） （13017KB）（423）       Save
    Expansive soil can damage the civil engineering structures due to the swelling-shrinking characteristic when they are exposed to the water. Middle Route Project of the South-to-North Water Diversion is an important project for alleviating water shortages and optimizing water resource allocation in the North China Plain. One third of water channel in the Middle Route passes through the expansive soil region, threatening the safety of the South-to-North Water Diversion Project. It is urgent to monitor the ground deformation of expansive soil slope so that better understanding its engineering stability. In this context, 112 Sentinel-1A synthetic aperture radar (SAR) images with ascending orbit were processed by multi-temporal interferometric SAR (InSAR) technique to observe the time series deformation along the South-to-North Water Diversion Project. Meanwhile, the singular spectrum analysis (SSA) technique was used to decompose the time series deformation to analyze the deformation characteristics. The uplift deformation was observed in the excavating expansive soil slope, where the maximum deformation rate was 18 mm/a. This uplift deformation was mainly due to the soil unloading and rebound. In the filling region, the subsidence was observed due to the soil consolidation and the maximum subsiding rate was 15 mm/a. The magnitude of ground deformation was correlated with the excavating and filling thickness:the deeper excavation means the greater uplift, and the higher filling means the greater subsidence. The precipitation and temperature, which can cause the deformation temporal delay of 2~3 months, are two main external contributor to the expansive soil slope. This study will provide the evidence to the stability assessment of expansive soil slope along the South-to-North Water Diversion Project.
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    Fine identification and characterization of rock mass discontinuities and its application using a digital photogrammetry system
    XU Wentao, LI Xiaozhao, ZHANG Yangsong, ZHU Honghu, ZHANG Wei, XUAN Chengqiang
    Acta Geodaetica et Cartographica Sinica    2022, 51 (10): 2093-2106.   DOI: 10.11947/j.AGCS.2022.20220359
    Abstract （650）   HTML （367）    PDF（pc） （15919KB）（761）       Save
    Identification of rock mass discontinuity and characterization of characteristic parameters are of fundamental significance to the study of rock mass behaviour and instability mechanism. In this paper, a photogrammetric system consisting of UAV aerial survey, GPS-RTK and close-range photogrammetry was employed to systematically investigate the rock mass discontinuities at different scales in Beishan area, Gansu province. The digital orthophoto map (DOM) of this site and 3D reconstructed digital surface model (DSM) of outcrops were established by using the ground object photos obtained from different perspectives. The effective interpretation of rock mass discontinuity information and characterization of characteristic parameters were realized by using digital identification and statistical methods. Studies of typical outcrops and areas show that the photogrammetric system can promote the fine investigation and identification of rock mass discontinuities from different dimensions and scales. According to the variation feature of discontinuity characteristic parameters, the fault affected zone of F31 fault in Beishan area were investigated. It can be preliminarily concluded that the affected range of F31 fault on hanging-wall rock mass integrity was approximately 150~200 m, and the influence form was negative exponential type.
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    GNSS landslide monitoring aligned to regional reference frames
    WANG Guoquan, BAO Yan
    Acta Geodaetica et Cartographica Sinica    2022, 51 (10): 2107-2116.   DOI: 10.11947/j.AGCS.2022.20220308
    Abstract （307）   HTML （40）    PDF（pc） （7848KB）（352）       Save
    Regional reference frames are the critical geodetic infrastructure for realizing high-accuracy crustal deformation and long-term landslide monitoring. According to the published results in active tectonic-block zonation and long-term GNSS observations, the authors divide China into seven “rigid-frame blocks” (or “rigid blocks”) and intend to establish the stable regional reference frame series covering the entire land and sea areas of China: Northeast, North, South, Northwest, Qinghai-Tibet, Sichuan-Yunnan, and South China Sea reference frames. This article introduces the method for realizing the coordinate transformation from the global reference frame (IGS14) to regional reference frames and exemplifies the applications of the North China Reference Frame (NChina20) and the South China Reference Frame (SChina20) in long-term landslide monitoring and initial slide automatic detection.
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    Switching method of GNSS landslide monitoring reference station considering the correction of motion state
    WANG Duo, HUANG Guanwen, DU Yuan, BAI Zhengwei, CHEN Zi, LI Yang
    Acta Geodaetica et Cartographica Sinica    2022, 51 (10): 2117-2124.   DOI: 10.11947/j.AGCS.2022.20220295
    Abstract （263）   HTML （26）    PDF（pc） （5694KB）（231）       Save
    GNSS relative positioning technology is widely used in high-precision real-time landslide monitoring, and this high-precision positioning relies on continuous and stable reference station data. However, the data of the reference station is often interrupted due to reasons such as power supply and communication, which seriously affects the continuity and reliability of the landslide monitoring results. This paper proposed a switching method of GNSS landslide monitoring reference station considering the correction of the motion state. First, the motion status is determined according to the long-term monitoring time sequence of the new reference station. Then, a displacement model is established based on the landslide deformation evolution law and motion state, and the model is checked regularly. Finally, the displacement of each monitoring point is corrected based on the actual displacement of the new reference. This method was successfully applied to the switching of the reference station of Heifangtai landslide monitoring in Gansu. After correction, the displacement of each monitoring station was close to the real deformation. The improved tangent angle was calculated as the landslide warning criterion, and the monitoring displacement sequences before and after the correction were used for warning. If no corrections are made, it may lead to a misjudgment of the early warning. Aiming at the problem of data interruption in the reference station, this method obtains a continuous and reliable landslide monitoring sequence by switching a new reference and correcting errors, ensuring the continuity of monitoring and the timeliness of early warning.
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    Research on application of spatio-temporal Kalman filter in deformation analysis
    SHI Qiang, DAI Wujiao, YAN Huineng, LIU Ning
    Acta Geodaetica et Cartographica Sinica    2022, 51 (10): 2125-2138.   DOI: 10.11947/j.AGCS.2022.20220292
    Abstract （391）   HTML （29）    PDF（pc） （10352KB）（530）       Save
    Spatio-temporal Kalman filter can be used for spatio-temporal data denoising, interpolation and deformation prediction. In order to use the spatio-temporal Kalman filter model for spatio-temporal deformation analysis, the performance and applicability of three typical spatio-temporal Kalman filter models, namely Kriged Kalman filter (KKF), space time Kalman filter (STKF) and spatio-temporal mixed effects (STME), are compared and analyzed from the aspects of principles and experiments. The results show that: in theory, the three spatio-temporal Kalman filter models are based on the combination of spatial basis function and dynamic model to describe the spatio-temporal correlation. The main difference lies in the expression of spatial data, such as trend term, fine-scale variation, observation noise and spatial basis function. In terms of applicability, the KKF model is more suitable for the spatio-temporal deformation analysis of sparse stations, while the STKF model and STME model are more suitable for the spatio-temporal deformation analysis of massive stations. In terms of application effects of spatio-temporal deformation analysis, the three spatio-temporal Kalman filter models have high-precision effect in denoising, data interpolation and deformation prediction performance. The average improvement rate of denoising results compared with ordinary Kalman model is 21.1%, the average improvement rate of interpolation results compared with Hermite time interpolation results is 42.4%, the average improvement rate of its spatio-temporal prediction results relative to Kriging spatial interpolation results is 65.3%, the average improvement rate of its spatio-temporal prediction results for observation stations relative to the time prediction results of ordinary Kalman filter is 20.6%, and the average improvement rate of its spatio-temporal prediction results for non-observation stations relative to the prediction results of Kalman filter+Kriging model is 20.5%.
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    Correction method of atmospheric phase for arc-scanning synthetic aperture radar in landslide monitoring
    DU Nianchun, WANG Yuming, SHEN Xiangqian, XIE Xiang
    Acta Geodaetica et Cartographica Sinica    2022, 51 (10): 2139-2148.   DOI: 10.11947/j.AGCS.2022.20220301
    Abstract （217）   HTML （20）    PDF（pc） （5953KB）（267）       Save
    Ground-based arc-scanning synthetic aperture radar realizes landslide warning through deformation measurement, and it is an important remote sensing method for landslide disaster monitoring. The atmospheric phase affects the accuracy of deformation value measurement, and the correction of the atmospheric phase is a key technology for long-term stable monitoring of the area of interest. In this paper, a two-stage atmospheric phase correction method based on grid division is proposed. This method obtains permanent scattering points through feature extraction and classification, realizes automatic screening of control points, and estimates atmospheric phase based on the grid. It effectively reduces the amount of computation, improves computational efficiency, and ensures the accuracy of atmospheric phase estimation by combining spatial and temporal filtering. The experimental results show the effectiveness of the proposed method in atmospheric phase correction.
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    A landslide multi-objective weighted displacement back analysis method synthesizing ground and underground displacement monitoring data
    DAI Yue, DAI Wujiao, YU Wenkun
    Acta Geodaetica et Cartographica Sinica    2022, 51 (10): 2149-2159.   DOI: 10.11947/j.AGCS.2022.20210163
    Abstract （301）   HTML （22）    PDF（pc） （6536KB）（443）       Save
    In view of the multi-objective optimization problem of landslide parameter inversion, and to compensate for the lack of sparse landslide displacement monitoring point, a landslide multi-objective weighted displacement back analysis method synthesizing ground and underground displacement monitoring data is proposed. Firstly, the multi-objective weighted displacement back analysis model is constructed by ground and underground displacement information. Secondly, the robust post-test random model of various observations is calculated by the robust Helmert variance component estimation method, and then it is used to optimize the inversion model. Finally, the equivalent mechanical parameters are solved by iteration computation. Experimental results show that insufficient amount of underground displacement information will lead to serious deviations in the displacement back analysis results, and the inversion results that integrate ground and underground displacement information are more accurate; the multi-objective weighted displacement back analysis method based on robust Helmert variance component estimation can not only reasonably determine the weight of different types of observation data, but also effectively resist the influence of abnormal gross errors on the inversion results, and improve the inversion calculation accuracy.
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