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    25 May 2024, Volume 0 Issue 5
    Integration of InSAR and airborne LiDAR technologies for early landslide identification and analysis
    ZHENG Wei, ZUO Xiaoqing, LI Yongfa, LI Zhenghui, WANG Zhihong, LI Debin
    2024, 0(5):  1-6.  doi:10.13474/j.cnki.11-2246.2024.0501
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    The insufficiency in the accuracy and dependability of early landslide identification in densely vegetated complex mountainous areas is tackled in this paper. A method for early landslide identification analysis is suggested, which combines the micro-topographic features from LiDAR data and the deformation characteristics from InSAR technology. Initially, the SBAS-InSAR technique is used to extract the temporal deformation information of the region, confirming the abnormal distribution range of deformation rates. Subsequently,leveraging the advantages of airborne radar in high-precision terrain and landform data, seven potential landslides within the main area are identified, and landslide maps along with the boundaries of potential landslides are delineated. Finally, the identification results are validated through optical image remote sensing and geometric distortion principles. The results demonstrate that the combination of InSAR and airborne LiDAR technologies can enhance the accuracy and detection capabilities of landslide identification. The developmental characteristics of landslides and the identification results provide theoretical support and a basis for the prevention of geological disasters and the cataloging of landslides in the Wenshan region.
    A combined method of PCA and IR-MAD for detecting rainfall landslide
    ZHAO Qiong, ZHANG Jinshui, ZHENG Wenwu
    2024, 0(5):  7-11,18.  doi:10.13474/j.cnki.11-2246.2024.0502
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    Seasonal patterns of torrential rainfall is one of the primary triggering agents which predisposes to catastrophic landslides, especially in the complex terrain medium-elevation mountains and hilly of China. The geographic scene resulted in landslide occurrence is very complex. Therefore, exploring the landslide detection methods in complex situations has important significance for damage assessment and post-disaster emergency investigation. In this paper, we propose a landslide detection method combining PCA and IR-MAD to realize the accurate extraction of nascent landslide.The research results show that compared with the existing methods, the proposed method effectively inhibits the disturbance of landslide detection caused by seasonal factors such as crop seeding and harvest, flood season caused by heavy rainfall, and other similar remote sensing features of bare land and tidal flat. The accuracy rate of landslide detection and the stability of landslide identification model have been improved to a certain extent.
    Study on sample unbalance in landslide recognition algorithm based on depth learning
    WANG Lixia, XI Wenfei, SHI Zhengtao, ZHAO Zilong, QIAN Tanghui, ZHAO Lei, MA Yijie
    2024, 0(5):  12-18.  doi:10.13474/j.cnki.11-2246.2024.0503
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    Landslides are a common geological disaster that can cause significant property losses and casualties to natural ecosystems and humans once they occur. How to quickly and accurately obtain landslide information is crucial to disaster prevention and mitigation. Traditional deep learning methods depend heavily on the quality of landslide samples, but the quality of existing samples is uneven, and the impact of landslide sample imbalance on the performance of deep learning models is rarely considered. Aiming at the problem of how to improve model accuracy by improving sample quality, this paper proposes a Faster R-CNN landslide target detection method based on multi-source unbalanced samples starting from sample quality. By conducting integrated training on a variety of imbalanced samples, the impact of different samples on the comprehensive performance of the model is studied. The results show that:①The accuracy rate of the model is 85.16%, F1 score of 0.69, precision of 56.96%, recall of 86.58%, and the missed detection rate is 0.33 under the imbalance of difficult samples. After strengthening the sample quality, the accuracy rate increases by 2.04%. The precision increased by 4.29%, the recall rate increased by 1.71%, and the missed detection rate decreased by 0.04. ②Under the imbalance of positive and negative samples, the accuracy rate of the model is 96.03%,F1 score of 0.78, precision of 64.50%, recall of 97.15%, and the missed detection rate is 0.09. After adding difficult samples to participate in the training, the accuracy rate drops by 8.45%. The rate dropped by 6.93%, the recall rate dropped by 7.25%, and the missed detection rate increased by 0.18. Difficult samples have a greater impact on the overall performance of the model. By improving the quality of these samples, the model detection accuracy can be improved. Therefore, the method proposed in this article provides a reference for solving the problem of landslide data sample imbalance in deep learning.
    Bathymetric inversion model for fusion of heterogeneous satellite remote sensing data
    GUO Songtao, XING Shuai, ZHANG Guoping, KONG Ruiyao, CHEN Li
    2024, 0(5):  19-23.  doi:10.13474/j.cnki.11-2246.2024.0504
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    To investigate the impact of image resolution and bathymetry models on the fusion of heterogeneous satellite data for depth inversion, this study integrates ICESat-2 laser altimetry data with multi-temporal Landsat 8, Sentinel-2, and WorldView-3 satellite data. Depth inversion is performed using logarithmic ratio model, multi-band model, BP neural network, support vector machine, random forest, and extreme gradient boosting. Experimental results show that the spatial resolution of the images has an insignificant effect on the accuracy of depth inversion. Considering both the accuracy and resolution of the inversion results, Sentinel-2 satellite data performs the best. Moreover, the XGBoost model outperforms other models in terms of inversion performance, achieving an optimal RMSE of 0.51 meters in the Dongsha Atoll experimental area. These results provide valuable reference for coastal depth measurement based on the fusion of heterogeneous remote sensing satellite data.
    Comparison of handheld LiDAR point cloud filtering methods for complex mountain microtopography
    XU Yajing, YUAN Xiping, GAN Shu, LI Raobo, YE Junmin
    2024, 0(5):  24-28.  doi:10.13474/j.cnki.11-2246.2024.0505
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    In this paper,a typical use case of hand-held laser point cloud data for measuring soil erosion and surface erosion in complex mountainous areas is presented,the performance of delta filter algorithm,slope filter algorithm and cloth simulation filter algorithm in point cloud classification of ground-based LiDAR is compared and analyzed. In order to obtain the highest performance,the parameters corresponding to three kinds of filters are used to test the test data set,and the optimal filtering of each algorithm is obtained through comparative analysis,the experimental results show that for smooth bare landform filtering,cloth simulation filtering is the best,progressive densification triangle filtering is the second,and slope filtering algorithm is the worst,the progressive encrypted triangle filter algorithm has the best filtering effect,the cloth simulation filter is the second,and the slope filter algorithm has the worst filtering effect. The experimental results provide valuable information for optimizing the parameters of the filtering algorithm to improve its performance in detecting micro-terrain changes,and verify the effectiveness of the progressive encrypted triangle filter in complex areas.
    A fine extraction method for tidal channels with fully polarized SAR and optical remote sensing
    LI Shu, LI Peng, LI Zhenhong, WANG Houjie
    2024, 0(5):  29-34,40.  doi:10.13474/j.cnki.11-2246.2024.0506
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    The tidal channel system is the most active geomorphic unit in the chalky-silt tidal flats. Due to the influence of periodic tidal erosion, human activities, and sea level rise, it is challenging to monitor tidal channel in a large scale. In this study, a method of tidal channel detection and extraction based on C-band GF-3 fully polarized synthetic aperture radar (SAR) and PlanetScope multispectral remote sensing data is proposed. Through the fusion of spectral, index, polarization, texture and other features, the optimal feature set was constructed, and the maximum likelihood method, support vector machine and random forest algorithm were combined to carry out synergetic classification, and the fine distribution information of the tidal channel at the Yellow River estuary with 3m resolution was obtained. The results show that the overall accuracy of the method is 99%, F1 value is 0.98, and the extraction result is better than that of a single data source. This study is expected to provide a cost-effective alternative for the tidal channel mapping in estuarine and coastal areas, and help to quantitatively describe the morphological evolution, stability and driving factors.
    Assessment of cultivated land use change in Guilin using the GeoSOS-FLUS model
    NI Chunyu, HE Wen, YAO Yuefeng
    2024, 0(5):  35-40.  doi:10.13474/j.cnki.11-2246.2024.0507
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    Information of spatiotemporal change in cultivated land and its future trends is an essential component for effective land use management. Here, we explore the spatiotemporal change pattern of cultivated land in Guilin with multi-temporal Landsat remote sensing images based on the Google Earth Engine (GEE) cloud platform. Firstly, we comprehensively evaluate five classification methods for their suitability in classifying land use in Guilin. Secondly, we analyze the land use changes, especially the spatiotemporal change pattern of cultivated land from 2000 to 2020. Furthermore, we simulate and predict change in cultivated land under different scenarios in 2030 using the GeoSOS-FLUS model. The results show that the random forest (RF) algorithm demonstrate the highest overall accuracy and Kappa coefficient for land use classification in Guilin. There was a continuous decrease in cultivated land area during 2000 to 2020, with the most pronounced decline observed between 2010 and 2015. Cultivated land was mainly converted to construction land and forests.The Grain for Green Program, the rapid expansion of tourism, and an increase in construction land are the key factors that impact the spatiotemporal change patterns of cultivated land.Under the natural development scenario, it is anticipated that the cultivated land will continue to decrease significantly, while construction land will expanse in 2030. This will have adverse impacts on the ecological environment.Under both the cultivated land protection and ecological control scenarios, an increase in cultivated land area is anticipated. Increase in cultivated land and optimization other land use types will have significant importance for safeguarding food security, promoting the sustainable development of tourism, and ensuring ecosystem stability in Guilin.
    Change and driving factors of vegetation coverage in the natural forest protection project area of Aksu prefecture
    KANG Juan, FANG He, SHI Shouhai, XIA Rui, PENG Jinling
    2024, 0(5):  41-47.  doi:10.13474/j.cnki.11-2246.2024.0508
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    In this paper, the natural forest protection project area of Aksu prefecture is taken as the research area.Based on MODIS satellite image data, the fractional vegetation cover (FVC) of growing seasonis produced based on pixel dichotomy from 2000—2020. Subsequently, the temporal variation and spatial distribution characteristics of long time series FVC are analyzed. Finally, the driving mechanism of vegetation coverage change is analyzed using the geographic detector model. The results show that the vegetation coverage in the research area increased significantly by 0.23%/a from 2000 to 2020. The area with significant increase in vegetation coverage accounted for 50.4%. Among the many factors, land use is the main factor affecting the vegetation cover in the study area, and the explanatory power reached 0.59. The explanatory power of population density, evapotranspiration and GDP on FVC is the secondary influencing factors, which are 0.360, 0.357 and 0.308, respectively. These results help to better understand the impact of human activities and natural factors on vegetation ecological quality cover changes and their interacting mechanisms.
    3D scene reconstruction system and algorithm based on stereo vision and single-line LiDAR
    ZHONG Leisheng, XIA Hui, CHEN Jialin
    2024, 0(5):  48-52,59.  doi:10.13474/j.cnki.11-2246.2024.0509
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    Stereo vision and LiDAR are two effective methods for 3D scene reconstruction, but they both have some limitations. As a result, it is meaningful to fuse visual sensor data and LiDAR data in order to conquer their weaknesses. In this paper, we address the uniqueness of the single-line spinning LiDAR device, and propose a modular visual-LiDAR SLAM algorithm based on the integration of image and range data. In the method, visual information is used to undistort the LiDAR point cloud and provide an initial pose estimation from the visual odometry (VO) module. After that, pose refinement is performed by a LiDAR SLAM (L-SLAM) module which is independent from the VO module, and then we obtain highly accurate 3D scene reconstruction results. Experiments show that our system and algorithm could increase the accuracy and adaptation of low-cost large-scale 3D scene reconstruction tasks.
    Multi-track sequential InSAR mining 3D deformation monitoring and prediction combined with Prophet-CNN model
    BI Zihang, LI Sumin, ZHANG Longyu, ZHANG Wei, LI Yuansong, YUAN Liwei
    2024, 0(5):  53-59.  doi:10.13474/j.cnki.11-2246.2024.0510
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    Due to the geological conditions and special mining methods of the mineral deposits, most mining areas are prone to cause the imbalance of geological stress in mining areas, resulting in different degrees of deformation and failure. In order to explore the surface stability of Dahongshan mining area under mining activities, the three-dimensional deformation field of Dahongshan mining area is calculated by combining the three-track SAR images covering the area from 2021 to 2023, and the deformation characteristics of the mining area are analyzed. On this basis, the Prophet-CNN model is used to train the deformation time series, and the deformation prediction model is built to predict the three-dimensional deformation trend of the mining area. The results show that the surface deformation occurs continuously under the influence of mining activities, and the deformation is mainly distributed in Xiaoshuiqing southern waste rock field, open-pit mining area and copper mining area, and the maximum vertical deformation rate is -51.22mm/a. The Prophet-CNN combined model is used to predict the 3D surface deformation in the mining area in time series, and the RMSE and MAE of the prediction results in the three directions are below 2.90 and 1.85mm, respectively, which fully indicated that the proposed method could be applied to the prediction of the subsidence trend in the mining area and provide technical basis for disaster prevention and reduction.
    Application experiment and analysis of high-precision engineering surveying network for BDS-3+BDS-2 dual-frequency data
    ZHOU Mingduan, BAI Yansong, JI Xu, XU Xiang, CUI Likun, XIE Qianlong
    2024, 0(5):  60-65.  doi:10.13474/j.cnki.11-2246.2024.0511
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    Aiming at the current stage of BeiDou system in BDS-3+BDS-2 hybrid service, this paper analyzes the data processing model of BDS network, and establishes a kind of high-precision engineering surveying network based on BDS-3+BDS-2 dual-frequency data for the application test. Four CORS stations that simultaneously support BDS-3+BDS-2 and GPS dual-frequency data are selected to lay high-precision engineering surveying network for data processing, and comparative analysis and evaluation are carried out in terms of the accuracy of phase observation values, standardized root-mean-square error after checking, quality of baseline vectors, repeatability of the baseline, and results of the net adjustment point coordinates. The experimental results show that: using the B1I and B3I dual-frequency data of BDS-3+BDS-2 to establish a high-precision engineering surveying network, the results of the obtained point coordinates are millimeter lever in horizontal direction and millimeter to decimeter level in vertical direction different from the corresponding results of the L1 and L2 dual-frequency data of GPS, which is effective to be applied to the high-precision engineering surveying network.
    An assessment of BDS/GNSS positioning accuracy based on RTS backward smoothing methods
    WANG Yifan, ZHAI Wei, MA Yi
    2024, 0(5):  66-70,84.  doi:10.13474/j.cnki.11-2246.2024.0512
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    To mitigate the issue of poor accuracy during the convergence phase of precise point positioning (PPP),we investigates the improvement of positioning accuracy using the RTS (Rauch-Tung-Striebel) backward smoothing algorithm. The evaluation of static PPP using the forward Kalman filter indicates that BDS can achieve an accuracy of 2.6mm,2.0mm,7.8mm in N、E、U direction. The GPS+Galileo combined PPP can achieve the best accuracy,which is 1.7mm,2.1mm,3.4mm in the N、E、U direction. The kinematic PPP using the RTS smoothing method indicate that an accuracy of 3.3mm,3.4mm,9.0mm can be achieved for the BDS PPP in the N、E、U direction. Introducing the GPS,GLONASS,or Galileo observations can improve the accuracy of BDS PPP by more than 50%. The analysis of on-vehicle dynamic testing further indicates that utilizing the reverse RTS smoothing algorithm for PPP calculations can achieve positioning accuracies of 0.028meters in the north direction (N),0.015 meters in the east direction (E),and 0.033 meters in the up direction (U).
    A new approach to single-epoch attitude determination for single-frequency low-cost GNSS receivers
    TAO Shiliang, WANG Chenzhe, WU Wentan, CHEN Yongli
    2024, 0(5):  71-76,126.  doi:10.13474/j.cnki.11-2246.2024.0513
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    GNSS attitude determination is increasingly applied in various navigation and positioning fields due to its cost-effectiveness. Navigation and positioning modules in the consumer market often employ low-cost receivers, which face challenges such as significant multipath effects, frequent cycle slips and integer ambiguities, among others. In complex urban environments, ambiguity fixing, a crucial component of GNSS attitude determination, encounters even more challenges. In this paper, based on the C-Lambda algorithm, we propose the C-Lambda-Search and C-Lambda-A Search methods. These methods involve a search for the degrees of freedom of another attitude angle when fixing ambiguities with a single baseline. They are employed to perform global minimization of the ambiguity function in both the attitude and ambiguity domains, aiming to calculate baseline vectors. We conduct static and dynamic vehicle experiments with three low-cost receivers (ublox-M8T) and patch antennas in different environments with varying baseline lengths.Both experiments demonstrate that the methods proposed in this paper significantly improve ambiguity fixing performance and Euler angle calculation accuracy. Furthermore, the computational burden remains within an acceptable range. These methods prove to be practical and effective for vehicle attitude determination.
    Real-time monitoring of axle linkage based on multi-source sensors analysis with response characteristics
    TU Liping, CAO Qing'an, TANG Bin, RAO Shaowen
    2024, 0(5):  77-84.  doi:10.13474/j.cnki.11-2246.2024.0514
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    With the rapid development of China's infrastructure,especially the transportation industry,bridge health monitoring technology has also made breakthroughs,so that the safety of bridges in operation and the safety of people's lives and property have been effectively guaranteed. However,the bridge health monitoring system only monitors the characteristics of the bridge structure itself and the response information,does not take into account the situation of vehicles about to go on the bridge,and lacks a visual assessment of the risk of accidents. Therefore,taking the Erganhe Bridge as an example,based on multi-source sensors,this paper proposes a method of vehicle-bridge linkage monitoring,real-time monitoring of bridge response information and driving vehicle information,and uses sensor monitoring data to study bridge response characteristics. So a bridge health monitoring and management platform based on vehicle-bridge linkage is established in the Erganhe Bridge to provide demonstration applications for the safe operation of the bridge.
    Lightweight fast satellite selection method based on minimum weighted geometric dilution precision
    SHEN Haoliang, LIU Hui, WANG Yixin, QIAN Chuang
    2024, 0(5):  85-89.  doi:10.13474/j.cnki.11-2246.2024.0515
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    With the increase in the number of navigation satellites and the development of chip technology,the number of observable satellites from GNSS terminals has greatly increased,greatly improving the satellite geometry. However,if all observation satellites are required to perform high-precision positioning calculations,the computing resources and power consumption required by the terminal will increase rapidly. To address this problem,this paper proposes a fast satellite selection method based on (weighted geometric dilution precision,WGDOP). When the number of satellites that can be solved is limited,a satellite combination with optimal geometric structure and signal quality can be obtained quickly. Experimental results show that compared with the traditional satellite selection method based on (geometric dilution precision,GDOP),when the number of satellites that can be solved is less than 15,the method proposed in this paper improves the accuracy and fixation rate by 10 times and 40% respectively. Then a real-time RTK test is conducted based on the AG3335 chip. Using the method in this article to select 20 satellites for calculation can greatly reduce the time-consuming of positioning calculation while maintaining high positioning accuracy.
    Progress and perspectives of urban functional region identification
    CHENG Penggen, QI Guangyu, ZHONG Yanfei
    2024, 0(5):  90-95.  doi:10.13474/j.cnki.11-2246.2024.0516
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    With the rapid development of the economy and society, the urban development boundary has rapidly spread from the center to the outside. Identifying urban functional areas can provide reference basis for urban construction and planning, and it is of great significance for the rational allocation and utilization of urban space and resources. Based on the literature review of urban functional area division and identification at home and abroad, this article summarizes the research status of urban functional area identification. Firstly, various data sources used for urban functional area identification are introduced, and their advantages and disadvantages are analyzed and compared. Secondly, it summarizes four types of method for urban functional area identification, focuses on analyzing the application of deep learning methods in urban functional area identification, and conducts case analysis and comparison to illustrate the effectiveness of different data sources and methods for urban functional area identification. Finally, the problems and research trends in the field of urban functional area division and identification are pointed out.
    An approach for extracting BIM component instance information integrating IFC semantic data and geometric similarity
    HE Biao, TANG Aowei, KUAI Xi, XU Hai, XIAO Jiadong
    2024, 0(5):  96-102.  doi:10.13474/j.cnki.11-2246.2024.0517
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    Building information modeling (BIM) accurately captures architectural structures,component compositions,and semantic attributes. It plays a crucial role in the digital management of smart cities' spatiotemporal frameworks and the entire building lifecycle,including planning,construction,maintenance,and operation. However,the massive data scale,complex reference relationships,and hierarchical structures of BIM models present challenges in extracting component instance information,hindering lightweight data transmission,seamless visualization,and BIM analysis within current city information modeling (CIM) platforms.To address this issue,we introduce an innovative approach that combines IFC semantics with geometric similarity. Utilizing ICP and the Hausdorff distance metric,we attain a high level of precision in extracting BIM component instances. Furthermore,we present a specialized method tailored to the extraction of common extruded components. Our comprehensive evaluation,encompassing five diverse BIM disciplines,demonstrates exceptional results,including a 29.79% reduction in file sizes,a 79.41% component instantiation rate,and a 22.47% solid compression rate. Impressively,each instantiated component encompasses an average of 49.24 sub-components. Our method excels in extracting IFC-based BIM component instances,facilitating the efficient transformation of extensive models.
    A method for automatic generating LOD2 building models based on energy function primitive extraction
    WANG Lin, CHEN Jianlong, LIU Zhaoliang, LIU Wenxuan
    2024, 0(5):  103-107,114.  doi:10.13474/j.cnki.11-2246.2024.0518
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    In recent years, with the rapid development of 3D real scene(3DRS), the reconstruction of 3D models of buildings has become an important part of smart city construction. This paper proposes a fully automatic framework for generating LOD2 building models, aimed at addressing the challenges of generating LOD2 building models for city-level 3DRS applications. In order to automatically extract building objects in large scenes, this study utilizes orthophoto images and acquires building boundary information through image segmentation. Subsequently, an enhanced plane region growing method is employed to extract high-quality segmented planes, with the results being optimized via a mixed linear model capable of better addressing issues like local damage and reconstruction errors in urban buildings. The experimental results indicate that the proposed method generates higher quality LOD2 building models and adeptly manages complex scenarios in urban building modeling, yielding more robust reconstruction outcomes.
    Remote sensing information extraction of sargassum from the in-shore shallow sea in Daya Bay
    LI Jun, HE Yingqing, DENG Ruru, XIONG Longhai, ZHANG Ruihao
    2024, 0(5):  108-114.  doi:10.13474/j.cnki.11-2246.2024.0519
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    Sargassum plays an important role in healthy coastal ecosystems. Remote sensing monitoring mostly studies of floating sargassum in the open sea, and less research on shallow seabed sargassum; technical methods are mostly based on empirical models and rely on a large amount of measured data. This paper establishes a sargassum remote sensing information extraction model based on the radiation transfer process of water bodies. The results of three experimental areas in Daya Bay show that:①The sargassum abundance distribution is essentially consistent with the field survey data. ②Sargassum in Daya Bay grows better and has a higher abundance when the water is highly open, the water exchange conditions are good, the water is affected by wind and waves, the bottom is sand-covered rocks or reefs, and the water depth is less than 1.6m.③Water depth and waves are important environmental factors that affect the growth and distribution of sargassum. The method in this paper has positive significance for the protection of sargassum resources and the construction of coastal biodiversity.
    Key technologies of point cloud processing for light and small airborne LiDAR
    HUANG Jiangxiong, CAO Qian, HU Xiang, CHEN Xiaojun
    2024, 0(5):  115-120.  doi:10.13474/j.cnki.11-2246.2024.0520
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    Aiming at the problem that the elevation accuracy of light and small airborne LiDAR point cloud data is difficult to meet the production requirements of 1∶500 large-scale topographic maps, this paper adopts a new hierarchical multi-model combined filtering method to classify and extract ground points. This paper systematically introduces the measurement principle of airborne LiDAR, the collection and processing methods of point cloud data, and focuses on the classification and extraction methods of ground points according to the characteristics of light and small LiDAR, such as large thickness of point cloud data and few ground points in dense vegetation areas. The new combination of multiple filtering models can effectively improve the elevation accuracy of ground points after classification. After resampling the ground points, the elevation points are extracted and used to draw contour lines of topographic maps. This method perfectly takes into account the accuracy and aesthetics of contour lines.
    Monitoring of early identification and ground deformation characteristics of coal mining subsidence area based on multi-data source:taking Daliuta Town of Shenmu city as an example
    ZENG Guang, ZHANG Pengfei, WANG Haiheng, WANG Yao
    2024, 0(5):  121-126.  doi:10.13474/j.cnki.11-2246.2024.0521
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    The ecological environment problems in coal mining areas have been paid more and more attention by the society. How to realize the accurate, efficient and economical early identification and dynamic monitoring of coal mining subsidence areas is particularly urgent. Based on the data collection and analysis, this paper uses the DEM data of 5 periods from 2000 to 2022 for differential decomposition calculation, and uses 164 long-term series Sentinel-1 data from June 15,2015 to July 15,2023 to dynamically monitor the land subsidence in the coal mining area. The current distribution and land subsidence characteristics of the coal mining subsidence area in Daliuta town, Shenmu city are identified, and a set of early identification methods of coal mining subsidence area based on multi-data sources is formed. The results show that:①The distribution area of coal mining subsidence area in Daliuta town is 252.70km2, including two types of ground collapse and goaf suspended roof. The coal mining subsidence problems in Shigetai, Halagou, Daliuta and Huojitu mining areas of Shenhua company are serious.②The DEM data with a resolution of 2m is resampled to 5m and then the difference operation is performed. The error is 0.01m, and the accuracy is high and the calculation is efficient. ③DEM difference decomposition and SBAS-InSAR technology can accurately identify the range of ground collapse with high matching degree, and each method complements and confirms each other.
    Application of hyperspectral remote sensing technology in the inversion cultivated land quality
    WANG Chenzhe, LIU Zhaoxian, FU Lizhao
    2024, 0(5):  127-132.  doi:10.13474/j.cnki.11-2246.2024.0522
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    This article estimates the related indicators of farmland quality based on hyperspectral image. The study area is in the northeastern plain of Shijiazhuang city,Hebei province. Based on the preprocessed ZY-1 02D hyperspectral remote sensing image,which underwent radiometric and geometric correction,a total of 110 surface soil samples within the image coverage were collected and subjected to physical and chemical analysis to obtain data on the content of farmland quality-related indicators. The inversion models for farmland quality-related indicators are established using the Hapke model,CARS method,and SVM model. Validation with 70% of the modeling samples and 30% of the prediction samples showed relatively high accuracy for hydrolyzable nitrogen and organic matter,confirming the application value of hyperspectral remote sensing technology for the inversion of soil organic matter and nutrient indicators.
    Segmentation and clearance inspections on overhead transmission powerline corridor based on LiDAR point clouds
    WANG Feiran, HAN Geng, GUO Xinyang, SHI Chaoyang, WANG Jin
    2024, 0(5):  133-137.  doi:10.13474/j.cnki.11-2246.2024.0523
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    The point clouds of transmission powerlines collected by UAV equipped light detection and ranging (LiDAR) effectively prompts the efficiency of clearance inspection in powerline patrol. However, there are problems in data processing including low classification performance of large-scene point clouds and low efficiency of clearance detection. A Light-weight Powerline (LP) network for classifying point clouds is investigated based on the practical LiDAR data from typical overhead transmission lines. A quadratic curve function of a simulated center powerline is fitted to represent the multiple powerlines, and the clearance is quickly measured between the center powerline and ground objects according to specifications. Two transmission power lines were applied to check the performance of the proposed method. The mean intersection over union (IoU) of LP network is 0.895 and the testing time is 9.53 s. The running time of measuring the clearance between two transmission towers is less than 1min. On important areas such as crossing other powerlines and railways, the clearance detection also achieved satisfied results. The research results could identify clearance obstacles automatically and accurately, and could provide decision support for powerline inspection.
    Tilt photogrammetry technology for mega cities based on helicopter flight platforms
    TAN Xiaodong
    2024, 0(5):  138-141.  doi:10.13474/j.cnki.11-2246.2024.0524
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    For mega cities with large areas, city level, and multiple sensitive areas, taking into account factors such as safety, efficiency, and airspace, a helicopter flight platform equipped with multi lens tilt cameras is adopted, and oblique photogrammetry technology is used to timely and effectively obtain on-site 3D real scenes. This project is based on the application of helicopter oblique photogrammetry technology in mega cities, which can quickly and efficiently obtain multi view high-resolution image data of the measured area. By using image data for 3D modeling, measurable 3D models can be constructed to meet the requirements of refined governance in mega cities.
    Application of comprehensive method of BeiDou/GNSS and precision leveling in old goaf collapse area surface deformation monitoring
    YANG Chunyu, YIN Hang, GUO Shuang, LUO Zhenhua, MA Fengfu
    2024, 0(5):  142-146.  doi:10.13474/j.cnki.11-2246.2024.0525
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    Based on the on-site situation in the research area, this article fully utilizes the advantages and complementarity of BeiDou/GNSS and traditional precision leveling, and conducts comprehensive measurement analysis, achieving the organic unity and combination of BeiDou/GNSS and traditional precision leveling in monitoring complex landforms and underground space areas with complex features. Firstly, the basic working techniques and methods of BeiDou/GNSS surface deformation monitoring and precision leveling are introduced. Then, taking the surface deformation monitoring project in the old goaf collapse area of the Muchengjian coal mine in western Beijing as an example, the surface deformation monitoring data of the research area in the past year are analyzed, and the deformation status and trend are predicted and evaluated. This article can provide reference for the monitoring and research of surface deformation in the old goaf collapse area.
    Road damage detection method based on lightweight vehicle equipment
    YAO Chuxian, CAI Haonan, ZHANG Yuanbo, TANG Keyi, ZHAN Lu, ZHOU Baoding
    2024, 0(5):  147-150.  doi:10.13474/j.cnki.11-2246.2024.0526
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    In response to the high cost and long detection cycle of traditional road detection methods, which can not meet the needs of large-scale and short-term detection of urban roads, this paper designs a lightweight vehicle mounted road damage data acquisition device and proposes a road damage detection method based on lightweight vehicle mounted devices. This device has the characteristics of small mass and low cost, and can be easily and quickly installed on common urban vehicles such as cars and buses, and synchronously collect inertial data, images, GPS positioning information, and other data. The road damage detection method proposed in this article is based on lightweight vehicle mounted devices, which collect road image data on urban roads to construct a dataset, establish a deep learning model for training and evaluation, and detect and recognize road damage. The accuracy rate is 82.54%, which can meet the requirements of daily inspection of urban roads.
    Real estate registration key technology based on 3D model
    WANG Zhaoze
    2024, 0(5):  151-154,159.  doi:10.13474/j.cnki.11-2246.2024.0527
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    Three-dimensional real estate registration can effectively reduce registration errors, improve the accuracy of real estate registration, enhance the intuitiveness of real estate registration information, and solve problems such as spatial information confusion in real estate registration. Based on the in-depth research of key technologies such as real 3D models and BIM involved in 3D real estate registration, this article achieves rapid query and accurate positioning of 3D real estate units through spatial matching and data association of attribute data and model data, provids more accurate and comprehensive data support for 3D real estate registration. It provides feasible reference and reference for the future development of 3D real estate registration technology.
    A method for extracting complex and difficult road networks based on deep learning models
    ZHANG Nan, ZHANG Yunling
    2024, 0(5):  155-159.  doi:10.13474/j.cnki.11-2246.2024.0528
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    With the wide spread application of high-resolution satellite image remote sensing technology, it also plays a huge driving role in transportation. There are technical difficulties in extracting rural road networks, such as data acquisition difficulties, inconsistent road features, natural environment interference, and frequent road changes. This study mainly uses high-resolution satellites as the main data source, and based on deep learning algorithms, learns the spectral, texture, and separable feature sets of different types of rural roads to identify rural roads with low grades and poor road conditions, which provides accurate data guarantee for the identification and discrimination of rural road networks, timely obtaining objective, accurate, and comprehensive basic data of rural roads solves the problem of insufficient road network information in complex and difficult areas. This study can serve scientific decision-making basis for the planning and construction of road networks in complex and difficult areas, and facilitates travel and traffic guidance.
    A study on activity semantics and transformation characteristics of Beijing geo-tagged places from the perspective of youth perception
    ZHAO Yuxin, YUAN Junlei, YI Disheng, JIN Sijia, ZHOU Huijun, ZHANG Jing
    2024, 0(5):  160-165.  doi:10.13474/j.cnki.11-2246.2024.0529
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    The youth group is passionate about documenting and sharing their life on social media platforms, making geo-tagged places one of the popular destinations for their outings and travels. The subjective experiences and feelings shared by users about geo-tagged places have been replicated and aggregated through the online space at the group level, affecting the functional attributes of these places. This study focuses on the area within the Sixth Ring Road of Beijing, using methods such as sentence vector representation, clustering, and multi-layer keyword extraction to obtain the activity semantics of the geo-tagged places. Based on this, the transformation between the functional and activity semantics of the geo-tagged places and their spatial distribution characteristics were analyzed using the diversity index and spatial clustering method. The results indicate that the activity semantics of geo-tagged places are more complex and diverse compared to functional semantics, reflecting a more human-centered perspective. The transformation between functional and activity semantics can be summarized as Combined, Consistent, and Derived. The characteristics of semantic transformation are closely related to regional functions, manifested in aspects such as the integration of historical culture, the mutual transformation of commercial complexes, and the meeting of diverse needs, thereby presenting a spatial distribution with clustering and regional characteristics.
    An updating method of the HD map confidence
    ZHAO Mingshu
    2024, 0(5):  166-171,177.  doi:10.13474/j.cnki.11-2246.2024.0530
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    The requirements by autonomous driving to HD maps, including high-precision, high-quality, and vast-coverage, which is less likely to be fully addressed with current technology. This paper proposes a method to convert low-precision observations into confidence of high-precision map elements, for they are different in spatial but very similar at feature level. It improves the strategy of HD map reliability without shorten its update cycle. The process starts with narrowing down matching scope and measuring matching rate, twice filtering using rectangular neighbor and a measuring model are employed to figure out the target from HD map. Followed by feature level analysis, status assessment and confidence score calculate, confidence of HD map elements get updated afterwards. Applying this method to our experiments with HD map includes 17 provinces, confidence of traffic sign gets updated via dash cam images. Moreover, two ways that could trigger out confidence update are verified, i.e. new observation and new map inputs. The results show redundant observations and confidence level are in positive correlation. When observation redundancy reaches 15, more than 80% of the target elements can maintain high confidence for 60 days, and the accuracy rate exceeds 96%. This study provides a solution to the conflict between high-precision map freshness and reliability, which can further promote the deepening of strategies of high-precision map applications.
    A new technology-supported fusion publishing method for stereo maps
    LI Yunxiang, ZHANG Di, ZHANG Ruizhuo
    2024, 0(5):  172-177.  doi:10.13474/j.cnki.11-2246.2024.0531
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    Stereo maps are bumpy maps that restore the surface of the earth according to a certain scale, which represents the latest development direction of physical maps. The physical characteristics of the stereo maps lead to many problems in the currency, spread, accessibility of information and user experience. Thus, a stereo map fusion publishing method under AR and other new technology is proposed, including the compilation and publication of offline stereo map and the construction of online interactive service system. Offline stereo map is a physical map made by map compilation and publication, stereo molding and other technologies. The online interactive service system is based on WeChat mini apps and adopts AR technology, which correlates stereo map with online integrated media information to realize the virtual and real fusion of map elements online and offline. This method not only breaks through the limitations of traditional 3D maps, but also explores a new publishing idea for the integration of science and technology with 3D map products,with a forward-looking.
    Development for the content of the engineering surveying under new engineering and technical disciplines:take the lofting and line measurement as examples
    LI Haojun, HUANG Liangke
    2024, 0(5):  178-181.  doi:10.13474/j.cnki.11-2246.2024.0532
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    Building upon the foundation of summarizing the development of the new engineering disciplines, this study combines the content of the engineering surveying course within the surveying and mapping major as well as the comprehensive applications of this course and the accumulation of corresponding foundational knowledge within the discipline. Under new engineering and technical disciplines, engineering surveying has great significance to expand new application thinking based on traditional content. The article discusses the teaching content expansion of engineering surveying taking the lofting and line measurement as examples under new engineering and technical disciplines.