Table of Content

25 June 2021, Volume 0 Issue 6

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Urban road extraction with fusion of high-resolution images and LiDAR data

LIU Maohua, LI Manwen

2021, 0(6):  1-5,60.  doi:10.13474/j.cnki.11-2246.2021.0166

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In order to avoid the problem of inaccurate road information extraction from remote sensing images due to the complexity of urban roads and the shadow occlusion of trees and buildings. The method of fusion of high-resolution images and LiDAR data is used to achieve the extraction of urban roads, and a post-processing improvement method based on the minimum area boundary rectangle (MABR) is proposed to improve the extraction. First, we realize the data registration in the area. Then, we apply the FNEA algorithm for image segmentation and use the random forest classification method for classification, apply image fusion and object shape index and other related operators to the road extraction. Finally we extract complete road information by removing the vegetation and buildings and improving the road filling. The results show that the road integrity of Toronto and Tai’an Study area is 95.41% and 90.84%, and the accuracy is 83.07% and 85.63%. This method can effectively remove false road information, improve the completeness of road extraction, and achieve better road information extraction.

Object-oriented eucalyptus plantation forest information extraction based on the red-edge feature of GF-6

WANG Ziyan, REN Chao, LIANG Yueji, SHI Yajie, LI Xianguang, ZHANG Shengguo

2021, 0(6):  6-11.  doi:10.13474/j.cnki.11-2246.2021.0167

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It’s very important to monitor the spatial distribution of eucalyptus forests, especially for regional ecological environment protection and the government’s decision-making. Based on existing research, this paper uses multispectral GF-6 image as the data source, the first satellite in China to provide red-edge bands. In this paper, selecting Luzhai county in Guangxi as a typical research area, combines spectral characteristics, vegetation index characteristics and red-edge characteristics to design different classification schemes. A class hierarchy is established by object-oriented multi-scale segmentation method. According to the different scale levels, membership functions and CART decision tree models are used to classify eucalyptus plantation information. The experiment results shows that the red-edge feature had a significant influence on the construction of the CART decision tree model. The integration of the GF-6 red-edge features could effectively improve eucalyptus plantations’ classification accuracy, with an overall accuracy of 91.75%. Comparing with the classification scheme that only using the traditional bands and vegetation indexs, the classification accuracy has been improved by 11.25%. The research results have important theoretical significance and practical value in the identification of eucalyptus plantations using red-edge bands of Chinese satellite.

Wetland classification method of Dongting Lake district based on CART using GF-2 image

CHEN Leishi, GAO Xiaxia, LIAO Yufang, DENG Jianbo, ZHOU Bi

2021, 0(6):  12-15.  doi:10.13474/j.cnki.11-2246.2021.0168

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In order to improve the classification accuracy of wetland classification through satellite remote sensing, it is necessary to overcome the “same object with different spectrum, different object with the same spectrum” problem which exists in the wetland classification of high spatial resolution satellite image. The research explores the combination of the Chinese sub-meter-level GF-2 image, which has a broad application prospect, and the object-based image analysis classification algorithm based on classification and regression tree. Then, the classification and extraction of wetlands in the Dongting Lake district were carried out by using the Yuanjiang city in Hunan as an example. Multi-dimensional object features including spectral information, geometric features, terrain features and texture features were selected to train the classifier. Constructed a set of wetland classification methods of classification and regression tree based on GF-2 image. Accuracy evaluation data shows that the overall classification accuracy of the method reaches higher value. The results show that the method can provide ideas for the classification of Dongting Lake district wetland based on GF-2 image.

High-resolution remote sensing image building change detection using structural objects

LIU Haifei, YANG Minhua, WANG Jing, XU Gang, CHEN Jie

2021, 0(6):  16-20.  doi:10.13474/j.cnki.11-2246.2021.0169

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According to the building with rich corner points and regular appearance shape characteristics, a method of building change detection based on line segment information to generate the basic unit of building change detection—the structural surface object is proposed.The edge lines and roof contour lines of buildings are extracted from high-resolution remote sensing images,then the structural surface objects are generated and the corresponding feature information is extracted from the two-phase images. And then,we obtain the changed building area through supervised classification. The experimental results show that the use of structural surface objects for building change detection can better cover the surface of the changed building and the object edge detection effect is better.

Building extraction in complex scenes based on the fusion of multi-feature improved PSPNet model

WU Hua, ZHANG Xinchang, SUN Ying, CAI Weinan, YAN Jun, DENG Jianwen, ZHANG Jianguo

2021, 0(6):  21-27.  doi:10.13474/j.cnki.11-2246.2021.0170

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Aiming at the problem of low accuracy of building extraction in complex scenes of high-resolution remote sensing images, this paper proposes an improved PSPNet model which integrates multiple features. On the basis of PSPNet network, the expansion convolution module is added and the shallow features of the image are fused. The results show that the overall prediction accuracy by the improved PSPNet model is 95.90%, and the average building extraction accuracy is 77.77%, which is higher than other models. It varies in performance from scene to scene. In the first scene that is complex the prediction accuracy is as high as 80.35%; in the second scene with village buildings in the city, the prediction accuracy is 75%; in the third scene with high-rise buildings, the prediction accuracy is 78.11%. This model can effectively improve the extraction accuracy of buildings in complex scenes of high-resolution remote sensing images.

BP neural network for near-surface ozone estimation and spatial and temporal characteristics analysis

LI Ziwei, MA Qingxun, Lü Jie

2021, 0(6):  28-32,126.  doi:10.13474/j.cnki.11-2246.2021.0171

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In recent years, photochemical smog pollution frequently occurs in the eastern cities of China. O₃, as a landmark pollutant of photochemical smog, is increasingly becoming the primary pollutant affecting urban or regional air pollution. To explore the Beijing-Tianjin-Tangshan (BTT) region surface ozone pollution characteristic and changing trend of time and space, this study based on feedforward (back propagation, BP) neural network, an inversion model of surface ozone concentration was established combined with the nonlinear relationship between the ozone concentration data of ground monitoring stations and the total ozone column data of satellite and meteorological data of meteorological stations. The results show that the R², RMSE, and MAE of the reliability evaluation model are 0.888, 10.742, and 9.596, respectively, and the accuracy of the established neural network model is relatively high. From 2016 to 2019, the annual average ozone concentration in the Beijing-Tianjin-Tangshan region showed an increasing trend. In the four seasons, ozone concentration in Beijing, Tianjin, and Tangshan are the highest in summer and the lowest in winter. The results provided a technical reference for near-surface ozone estimation and have important practical significance for environmental monitoring.

An automatic algorithm of power line extraction from LiDAR point cloud

LI Deyou, LI Cailin, LI Xiangshen, WANG Baitao

2021, 0(6):  33-38.  doi:10.13474/j.cnki.11-2246.2021.0172

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Aiming at the problem of low automation and accuracy of current power line extraction methods, this paper proposes an automatic power line extraction method based on the spatial distribution characteristics of point cloud data. Firstly, based on the nature breaks, the point cloud data is classified according to the elevation, and the ground points are removed. Then, the data is partitioned spatially. Based on the point density of subspace and the difference of spatial structure features, the pylon points and residual vegetation points are removed by ground object segmentation algorithm. Finally, the power line automatic detection algorithm based on Euclidean distance is used to realize the fast and high-precision extraction of a single power line.The results of extraction and fitting experiments show that this method can automatically extract power lines in complex terrain, and greatly improve the efficiency and accuracy of power line extraction.

Influence of U-Net model on the accuracy of shelter forest extraction with different spatial resolutions

WANG Xuewen, ZHAO Qingzhan, TIAN Wenzhong, LONG Xiang, JIANG Ping

2021, 0(6):  39-43.  doi:10.13474/j.cnki.11-2246.2021.0173

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Aiming at the problem of high-accuracy of UAV image acquisition but small data scale, this paper proposes to use U-Net model to explore the influence of different spatial resolution on the extraction accuracy of farmland shelterbelts. Take the CW-20 compound-wing UAV equipped with Micro MAC12 Snap multispectral sensor obtained three different height of 300 m(spatial resolution 0.15 m), 400 m(spatial resolution 0.20 m) and 500 m(spatial resolution 0.25 m) as an example. For remote sensing images, experiments results have shown that the accuracy error of image extraction at three different height is within 1.3%, and the accuracy error of MIoU is within 3.7%. The spatial resolution had little effect on the extraction accuracy of shelterbelts. The image data with high spatial resolution can not significantly improve the extraction accuracy of shelterbelts. This study provides a theoretical basis for the acquisition of large-scale agricultural and forestry remote sensing monitoring data sources.

Object-oriented classification of high-resolution image combining super-pixel segmentation

NIE Qian, QI Keke, ZHAO Yanfu

2021, 0(6):  44-49.  doi:10.13474/j.cnki.11-2246.2021.0174

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In order to solve the problem that high-resolution remote sensing image object-oriented classification is easy to be affected by segmentation parameters and the classification accuracy is not stable, this paper proposes an object-oriented classification of high-resolution image combining super-pixel segmentation. In this method, a simple linear iterative clustering algorithm is used to cluster the original image to generate the super-pixel image. On this basis, the fractal net evolution approach is used for multi-scale segmentation to generate homogeneous objects. Finally, the nearest neighbor classification method is used to classify the ground objects. The experimental results show that the method is not easily affected by multi-scale segmentation parameters, the classification effect is stable, and the classification accuracy is significantly higher than that of the traditional object-oriented classification method, which is of great significance for the wide application of high-resolution remote sensing images.

Development and prospect of image assisted total station and image measurement

ZHANG Houtian, ZHENG Yong, CHEN Bing, CHEN Zhanglei

2021, 0(6):  50-53.  doi:10.13474/j.cnki.11-2246.2021.0175

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As a widely used measuring instrument, total station can only aim at one object at a time, and the efficiency and accuracy are often relied on people who conducts it. Both defects can be eliminated exactly by using image assisted total station (IATS), which is most likely to replace conventional measuring appliances in the future. Based on the integration of coaxial camera in total station, the real-time, high precision, and high stability of the total station are combined with the technical advantages of cameras such as non-contact, surface measurements and no human error. Therefore, IATS have extensive application prospects in fields such as astronomic surveys, deformation monitoring, precision engineering surveys, and topographic mapping. By introducing the concept of IATS and its development, this paper analyzes the characters of IATS and its possible applying fields. Based on the analysis of the features of IATS and possible application areas and combined with the defects when measuring with IATS, certain direction for the future development will be revealed.

Analysis of the development status and key technologies of high-precision map

YANG Zhenkai, HUA Yixin, ZI Lu, ZHANG Zheng, WANG Jiwei

2021, 0(6):  54-60.  doi:10.13474/j.cnki.11-2246.2021.0176

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As the national strategic task for the innovation and development of intelligent vehicles is put forward and advanced, high-precision map has become a research focus in recent years. While high-precision map as a core element in automatic driving has been widely studied in many fields such as surveying and mapping, comprehensive theoretical research of its development status is still lacking. In this study, the definition of high-precision map and analysis on its comparison with traditional digital maps are firstly introduced. Then the main research and related works are divided into three categories, from the aspects of data structure, data production, function and application of high-precision map which are elaborated and summarized. From the perspective of data structure, high-precision map includes static map data and dynamic map data, with the former being the focus. In consideration of the level of data production, the production mode, process and specific technical methods of high-precision map are respectively analyzed. It is believed that the combination of professional department guidance and crowd-sourcing will be the basic feature of data production in the future. Then the key technologiesin high-precision map application are summarized, which play an important role in positioning and navigation of automatic driving.Some prospects about high-precision map and its future research are also made.

Monitoring of surface deformation in Yunnan based on Sentinel data

WENG Changkai, ZHU Xipeng

2021, 0(6):  61-66,92.  doi:10.13474/j.cnki.11-2246.2021.0177

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As a province connected to Tibet in southwestern in our country, the terrain of Yunnan province gradually decreases from the northwest to the southeast, and there are many mountains. The mountains area can account for 88% of the province’s area. In addition, Yunnan province is also located near the junction of the Indian Ocean plate and the Asia-Europe plate. It has many seismic belts and frequent geological movements, and there are frequent geological disasters such as earthquakes, landslides and mudslides. Therefore, this paper selects Sentinel data from northwestern in Yunnan, which covers a relatively high terrain, and uses SBAS-InSAR technology for data processing. The purpose is to monitor the surface deformation in northwestern in Yunnan and discover hidden areas of geological hazards, which will be the subsequent geological hazards. Early warning is provided on data support.

Monitoring surface deformation caused by land backfill using Sentinel-1 image

YANG Yingxin, HONG Wusheng, WU Manqiao

2021, 0(6):  67-70.  doi:10.13474/j.cnki.11-2246.2021.0178

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In order to monitor the safety of the airport surface deformation, the synthetic aperture radar interferometry (InSAR) technology is used to monitor and analyze the stable scattering of the airport reclamation area. The annual deformation rate data results and high-resolution deformation time series results in the study area are obtained by inversion, and the temporal and spatial distribution characteristics of surface deformation in the monitoring period Hong Kong international airport are analyzed. In order to prove the accuracy and reliability of the monitoring results, the vertical displacement data of GNSS (global navigation satellite system) observation station is used to cross verify the inversion results of InSAR method, which proves that the two methods have good consistency.

Urban land subsidence monitoring using multi-sensor SAR datasets

ZHU Xingang, LI Geng’er

2021, 0(6):  71-75.  doi:10.13474/j.cnki.11-2246.2021.0179

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In the past few decades, Los Angeles has occurred severe surface deformation due to human factors such as natural disasters, urban construction, groundwater extraction and oil extraction. The purpose of this study is to map the distribution of surface deformation rates in Los Angeles, and use improved SBAS (small baseline set) technology and multi-sensor SAR data sets to analyze the causes of deformation in the area from October 2003 to October 2017. At the same time, the deformation results of SBAS inversion, GPS measurement results and the deformation results of the multi-sensor SAR data set are compared, and the results are highly consistent. The results show that between 2003 and 2017, settlement and uplift occurred in many areas of Los Angeles. The maximum cumulative settlement was -266.8 mm, and the annual average settlement rate was -19 mm/a, which was mainly caused by the excessive exploitation of groundwater. The maximum cumulative up lift was 104.8 mm, and the annual average uplift speed could reach 7.5 mm/a. The research results have good practical application value and can provide an important basis for the local government’s disaster prevention and mitigation.

Joint InSAR and GNSS to monitor land subsidence in coastal areas

YANG Guochuang, DUAN Chunlei

2021, 0(6):  76-82.  doi:10.13474/j.cnki.11-2246.2021.0180

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The traditional point-based geodetic monitoring technology has limitations for regional surface deformation. Spatial geodesy technology proposed in this paper is used to study the surface deformation of the city. In the study, time-series InSAR and GNSS technology are used to monitor the surface deformation field in the coastline area of Shenzhen and Hong Kong Special Administrative Region of China. At the same time, a time series of three-dimensional changes at the network reference station in the Hong Kong Special Administrative Region is generated. The results show that there is a significant substitution phenomenon in the reclamation area, especially in the subway construction area and the buildings with shallow foundations in the reclamation area.

Joint InSAR technology and geological data to inverse the surface subsidence characteristics of Puning city

LI Bingfeng, YANG Yingxin, WANG Dongkai, WU Yujin, ZHANG Zhiyou

2021, 0(6):  83-88.  doi:10.13474/j.cnki.11-2246.2021.0181

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Surface subsidence is one of the global geological hazards problems. Rapid subsidence of the ground can lead to surface collapse, which can damage underground pipelines as well as surface buildings and eventually cause huge economic losses and even casualties. This geological hazards problem is particularly acute in China, where underground projects and surface buildings are undergoing massive expansion. There are many methods to monitor the surface deformation, such as level measurement, GPS, InSAR technology and so on. However, usually these techniques can only quantitatively analyze the elevation change of the ground surface, but cannot find out the causative factors for the occurrence of disasters, and lack qualitative analysis of the spatial and temporal characteristics of the ground settlement. In this paper, the InSAR technology is combined with the hydrogeology characteristics of the area. It takes the Puning area in Guangdong as an example, to realize the whole process of surface subsidence monitoring from data acquisition and processing to the analysis of the causes. In this paper, this analysis method not only investigates the subsidence area in the Puning city area, but also provides a systematic analysis of the causes behind it, which provides a more scientific guidance for the subsequent prevention and control measures.

Inland salt marsh wetlands information extraction from high-resolution remote sensing image based on convolution neural network

JIA Wenhan, LIU Yueyan

2021, 0(6):  89-92.  doi:10.13474/j.cnki.11-2246.2021.0182

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Based on Landsat 8 image, GF-2 image, DEM data generated by LiDAR data interpolation and census data of geographical conditions in Yanchi, Ningxia, in this paper, the best time phase of inland salt marsh wetland extraction is determined by using Landsat 8 image. Then the best time phase of GF-2 fusion image is segmented by multi-scale overlay, and NDVI, DEM, Tasseled Transformation and other features are selected. The nearest neighbor classifier is used to obtain the information of inland salt marshes, and the inland salt marshes sample database is constructed. On this basis, the convolution neural network method for extracting inland salt marshes from high-resolution satellite images is discussed. The experimental results show that the convolution neural method is suitable for inland salt marsh wetland extraction. Ccompared with the nearest neighbor classification method, the extraction effect of inland salt marsh wetland is significantly improved.

A coarse-to-fine method for slope deformation detection

RONG Yanxiang, GONG Zheng, CHEN Zequan, YANG Bisheng

2021, 0(6):  93-97.  doi:10.13474/j.cnki.11-2246.2021.0183

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Many slopes will be formed during modern engineering construction, and once these slopes are accidentally damaged, they will pose a great threat to public live and property. Therefore, continuous deformation detection of theslope is very important. TLS is a modern slope detection method. Based on TLS, this paper proposes a coarse-to-fine method for slope deformation detection. For the two-stage slope point clouds after good registration, the distance between the nearest matching points of the two-stage point clouds is calculated, and then rough detection is carried out. During the precise detection, the general direction of deformation is estimated firstly, and then the point withthe largest FPFH is searched as the corresponding point according to the direction vector. Finally, the distance from the point to the plane where the corresponding point is located is calculated as the deformation. Experiments show that the proposed method can effectively calculate the actual deformation of the slope, and it is practical.

Application of high-precision real texture 3D modeling in Ming Dynasty stone tablet

QI Yongliang, LI Haipeng, WANG Yongguo

2021, 0(6):  98-102.  doi:10.13474/j.cnki.11-2246.2021.0184

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In order to solve the problem of fine modeling of 3D surveying and mapping of cultural relics, this paper mainly discusses the use of hand-held high-precision three-dimensional laser scanning technology to study the high-precision real texture three-dimensional laser scanning modeling of Matteo Ricci tombstone, Tang ruowang tombstone and Nan Huairen tombstone in the palisade cemetery, which ensures the accuracy, precision and integrity of the cultural relic model. Hand held high-precision 3D laser scanning technology combines triangulation, laser measurement, close range photogrammetry, self positioning and other technical means to realize the fine mapping of complex texture cultural relics with a certain volume. In this paper, through the analysis of the basic principles of triangulation and close range photogrammetry, a set of 3D scanning technology process for fine texture and complex carving is explored by combining the characteristics of the two technologies. Through the research of hand-held laser scanning technology, the feasibility and reliability of this technology for cultural relics surveying and mapping are verified, which summarizes a set of new technical process for meso scale volume cultural relics surveying and mapping, and lays a foundation for future exploration of 3D surveying and mapping of cultural relics with different volumes and integration of various surveying and mapping technologies.

Putting up oblique photography real 3D data processing cluster using ContextCapture

WEI Jinming, ZHAO Xiangyang

2021, 0(6):  103-105,116.  doi:10.13474/j.cnki.11-2246.2021.0185

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In order to improve the modeling efficiency of large-scale, high-resolution, high-precision and mass tilt photogrammetry data, analysis the current modeling software, equipment configuration and cluster architecture, putting up oblique photography real 3D data processing cluster. The oblique photography data processing software is ContextCapture, select the optimal device configuration of computing node,reasonable planning of cluster architecture,laying 10 Gigabit optical fiber,build oblique photography real 3D data grid processing cluster including 100 computing nodes. The running status of the cluster is monitored by real-time monitoring platform. Its effectiveness is verified by the application of oblique photography real 3D data build in Jinan.

Landslide deformation monitoring using TLS technology and pseudo-single point monitoring model

GUO Xiantao, HUANG Teng, JIA Yan, ZHANG Rongchun

2021, 0(6):  106-111.  doi:10.13474/j.cnki.11-2246.2021.0186

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To overcome the limitations of traditional sparse points monitoring model unsuitable for TLS deformation measurement, and the deficiencies of the existing methods using TLS technology such as the one-dimensional characteristics and only available to the deformation analysis of regular geometry objects. This paper proposes a pseudo-single point monitoring model and a deformation computing approach based on TLS measurement, through constructing the generalized Gauss-Markov model to match and estimate the 3D deformation parameters of the selected pseudo-single point objects, full 3D deformation information can be get with high precision utilizing the high density of multi-period TLS data. It is especially suitable for the landslide field and other disaster monitoring. Finally, experimental results show that this method can achieve 1 cm deformation extraction accuracy when the scanning distance is about 240 m, which is of certain value in promoting the transformation of deformation monitoring from point mapping to shape mapping.

Application of AHP-entropy weight method in hazards susceptibility assessment in mountain town

QI Yuna, WANG Lei

2021, 0(6):  112-116.  doi:10.13474/j.cnki.11-2246.2021.0187

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Many towns in the southwest China are faced with the threat of geological disasters such as collapse and landslide. Therefore, it is important to research hazards susceptibility in the mountainous towns. In this work, hazards susceptibility in Yangjiao town, Wulong district, Chongqing city is studied. The predisposing factors of geo-hazards are determined, then the weight of each assessment factor is determined by combining the AHP method and entropy weight method, and at last the susceptibility index is used in susceptibility zoning of the study area based on ArcGIS,and susceptibility zones are consistent with the geo-hazards distribution. The combination method used in this research firstly determines the subjective weight with the AHP method, and then revises the weight with the entropy method, which reduces the subjective influence to a certain extent, and quantifies the geo-hazards susceptibility more accurately and reasonably. The research ideas can provide reference for risk assessment and prevention of geological disasters in mountainous towns.

Modeling and analyzing the potential impact range of geological disasters caused by the escarpments

ZHANG Hao, WEN Jianfeng, CHEN Wenqing, XU Gang, SHI Ruijie, DAI Xinyi, CHEN Jie, ZHU Anfeng, FAN Quanlong

2021, 0(6):  117-121,133.  doi:10.13474/j.cnki.11-2246.2021.0188

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As a special topography, escarpments are one of the important factors causing various geological disasters such as landslides and mudslides. Geological disasters caused by escarpments will destroy man-made surface features and cause serious harm to the safety of human life and property. Based on the DEM data, we extrac the escarpments in Wenzhou, Zhejiang province, conduct a systematic study on the range of influence of the escarpments, and construct a potential landslide direction model ofthe escarpments in Wenzhou. We also determine its impact on man-made features (such as roads, houses). The main contents of this study are as follows: ①extracting the escarpments and modeling their potential landslide directions; ②extracting the affected artificial ground features according to the scope of influence and establishing a basic database. The results show that Wenzhou has a large number of escarpments, a wide range of distribution and concentration, and the geological disasters caused by them will have serious potential impacts on man-made surface features. The basic database constructed in this paper can describe the locations of houses and roads potentially affected by escarpments, determine key disaster prevention areas, and serve Wenzhou’s disaster prevention and control work.

A method of the real estate data integration based on weighted similarity model

LONG Beiping, WU Jiajie, ZHENG Qinhua, SUN Liheng, LIU Kunming

2021, 0(6):  122-126.  doi:10.13474/j.cnki.11-2246.2021.0189

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In order to complete the connection between the project results of the real estate register survey and the real estate register information system,to realize the integration of the data of the real estate register survey, comprehensively consider the massive, multi-source and heterogeneous of data, etc., we propose a euclidean distance and similar coefficient and establish a normalized comprehensive index on describing the approximation of data samples—similarity distance. According to the maximum value to determine the correlation target,and achieve land parcel matching. Through the application of experimental evaluation and algorithm benefit analysis,which can improve the efficiency on personnel input, completion cycle and funds, at the same times has a generalized significance in the field of data integration.

An epipolar image generation approach combined object-based and image-based method for linear array satellite imagery

LIU Rui, CHEN Xiangguang, LIN Chao

2021, 0(6):  127-133.  doi:10.13474/j.cnki.11-2246.2021.0190

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Towards the issue of epipolar resampling for linear array satellite stereo-imagery, we analyze the advantages and disadvantages of the off-the-shelf methods. Then a new epipolar resampling approach that combines the Object-based and Image-based method is proposed. The approach has two steps. Firstly, the left epipolar image is resampled with the Image-based technique. Specifically, we divide the left original image space into several regular rectangular grid, then each grid is rotated independently to make epipolar direction parallel to the image line. After that resampling is achieved using local affine transform model. Secondly, both the right and left image are projected onto a datum plane in the object space to resample right epipolar image that has the same resolution as the left image. Experiments on five pairs of stereo pairs and comparison with the two prevailing methods show that the proposed method not only can obtain the epipolar image product with vertical parallax close to zero and superior to the comparative method, but also can guarantee the linear proportional relationship between horizontal parallax and elevation. In particular, the experimental results of three groups of larger epipolar line curvature data confirm that this method has good robustness and applicability, the proposed method could be well applied to different sensor data processing systems.

Key technology of unified address enabling social governance

CHEN Chaoyi, RU Hu, JIAO Chaofeng

2021, 0(6):  134-138,146.  doi:10.13474/j.cnki.11-2246.2021.0191

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The concept of unified address has been proposed only in recent years. Its main essence and significance is to serve as a “bridge” for the effective relevance integration of the elements of social governance on the basis of full respect for the existing industry standard address of each department. Provide support for the delicate governance work, such as mapping out the bottom numbers and precise policy-making, which is an innovative application of surveying and mapping geographic information technology in the field of digitization and intelligence of social governance. This paper makes a preliminary study on the key technology of the unified address in the construction process, and briefly introduces the practical application of Hangzhou city. At present, the Hangzhou mode of unified address construction has been popularized in Zhejiang province.

Construction of natural resources investigation and monitoring system in Hunan province

CHEN Genliang, GUO Shuangren, QUAN Sixiang, MA Xinnian

2021, 0(6):  139-142.  doi:10.13474/j.cnki.11-2246.2021.0192

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The natural resources investigation and monitoring work has been scattered in various departments for a long time in our country, such as natural resources department, forestry department, water resources department and agricultural sector. It is difficult to share their results due to the lack of uniform standards and methods. Based on the major project of the 14th Five-Year plan for natural resources in Hunan province, this paper analyzes the current situation of natural resources investigation and monitoring and explores the basic ideas for the construction of the natural resources investigation and monitoring system, which can provide the reference for the compilation of the 14th Five-Year plan for natural resources in Hunan province.

Thinking about the acquisition of high-precision geographic information as an important strategic task of basic surveying and mapping

WANG Wei, RUAN Yuzhou, WANG Chenyang

2021, 0(6):  143-146.  doi:10.13474/j.cnki.11-2246.2021.0193

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High-precision geographic information has the advantage of providing higher spatial positioning accuracy and stronger ability to express spatial relationships. During the “Fourteenth Five-Year Plan” period, high-precision geographic information acquisition will be taken as an important strategic task for basic surveying and mapping. The relevant achievements will provide a better spatial reference for economic and social development and integrated management of natural resources. Based on the progress of acquiring high-precision geographic information, this paper analyzes the demand situation and the role of improving the basic surveying and mapping service capabilities of high-precision geographic information products, as well as the problems encountered in the process of acquiring and providing high-precision geographic information. The suggestions for improving the ability to acquire high-precision geographic information and provide products are also proposed.

Teaching reformation of GIS major for physical geography field practice

WU Xiaofang, ZHONG Xiaolan, XIE Gangsheng, HE Zhengyong

2021, 0(6):  147-151.  doi:10.13474/j.cnki.11-2246.2021.0194

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Based on analyzing the shortcomings of traditional physical geography field practice, the management platform of physical geography field practice is developed with the technologies of GIS, RS and 3D visualization in this paper according to the guidance of the Ministry of Education on strengthening the reform of practice teaching and promoting the construction of practice information. The platform implements the integration of multi-source heterogeneous data, one-stop management of practice, route planning, expression of thematic map and three-dimensional virtual practice, etc. The platform provides a new way of information management and virtual simulation for physical geography field practice, which has strong practicability and promotional value.

Reform of cartography course teaching content in the era of big data

LIU Huimin, DENG Min, LIU Baoju, CHEN Jie

2021, 0(6):  152-155,165.  doi:10.13474/j.cnki.11-2246.2021.0195

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Combined with the development of big data and map application, this paper analyzes the teaching content of cartography course in the era of big data, including the differences of reference system of multi-source geographic information, the visualization of multi-type geographic information, the representation of multi-scale maps, the various needs of map users. In view of these new requirements, the main ideas of curriculum reform are put forward by considering the theoretical and practical objectives of cartography. Especially, this reform involves the mathematics foundation of cartography, map visualization technology, map generalization and map analysis. Moreover, the new coordinate systems, multi-dimensional dynamic visualization, multi-scale representations and pan-information-based map theory are added as the main knowledge points. Correspondingly, these new contents are assigned in the experimental teaching of the course.

The application of time series regression prediction model in automated monitoring

LIU Jianjun, WANG Jiawei, CHEN Kun, HAN Sanqi

2021, 0(6):  156-158.  doi:10.13474/j.cnki.11-2246.2021.0196

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In the process of slope automation monitoring, because of the interruption of transmission signal, equipment failure, power supply interruption and sensor replacement, the phenomenon of missing monitoring data will inevitably occur. The lack of monitoring data brings uncertain factors to the subsequent slope stability analysis and prediction, which makes the analysis results deviate. This paper aims at the phenomenon of missing dynamic monitoring, the time series regression prediction model is used to fill in the monitoring data of slope with different missing data rates. The absolute error and root mean square error between the filling value and the real value are used to judge the filling effect of different missing data rates. It is concluded that the model has good effect on missing data with missing rate less than 10%, and has certain practice.

Fusion application based on 3D laser scanning data and tilting photogrammetry data of UAV

LIU Baohua, WANG Zhi, SONG Yunji

2021, 0(6):  159-162,165.  doi:10.13474/j.cnki.11-2246.2021.0197

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In the acquisition of 3D real scene data of buildings, ground 3D laser scanning and UAV tilt measurement are frequently used technical means. The data types obtained by the two means are different, and the display effect and accuracy of space are also different, especially in obtaining the top and near ground data of buildings. This paper studies the processing of the top data of buildings and the near ground 3D laser scanning data are processed, and the point cloud and model data are transformed and matched. The methods of field survey and internal processing are introduced by data acquisition of a ancient gate, and the fusion accuracy is analyzed and discussed.

A method for converting a BIM model coordinate system to an engineering coordinate system

HAN Feiluo

2021, 0(6):  163-165.  doi:10.13474/j.cnki.11-2246.2021.0198

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Under the circumstance that engineering surveying technology cannot break through the existing development mode, the emergence of BIM technology makes the development of surveying technology change qualItatively. BIM model contains a large amount of measurement information, but due to the randomness of the selected axis network position during modeling, the coordinate system transformation is also needed after the data of the model feature points are read. Based on the characteristics of BIM technology and the research on the traditional coordinate system conversion method, this paper develops a method for converting the BIM model coordinate system to the engineering coordinate system.