Table of Content

25 January 2022, Volume 0 Issue 1

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Classification of building group patterns using graph residual neural network

ZHANG Ziqiang, LIU Tao, DU Ping, SUO Xuhong, YANG Guolin

2022, 0(1):  1-7.  doi:10.13474/j.cnki.11-2246.2022.0001

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Buildings are important features in the city, the analysis of building group patterns is of great significance in many fields such as map generalization, navigation, municipal planning and so on. Traditional methods for the recognition of building group patterns can be roughly divided into two categories:rule-based methods and machine-learning methods which require a lot of manual processing. In recent years, deep learning, especially the graph convolution neural network's emerging that does not require prior manual processing and can improve the automation degree of the analysis of building group patterns. Traditional graph convolutional neural network model is prone to degradation when training deep networks, which makes it difficult to extract deep features. To solve this problem, a graph residual neural network (GResNet) model is proposed for the classification of building group patterns. Firstly, the roads and rivers are used as constraints, and the K-means method is used to cluster the buildings. Secondly, many indices are used to compute Bertin's visual variables. In each building group, the centroids of the buildings are taken as nodes, and the minimum spanning tree is used to generate edges connecting nodes, after that, the graph representation for building group is constructed. Finally, the building graphs are taken as the input of the proposed GResNet model, and two building group patterns are obtained, namely, regular groups and irregular groups. Experiment results confirm that the proposed model can solve the degradation problem of the traditional graph convolutional neural network model, and obtain higher accuracy.

A method of urban facility hot spot recognition considering attribute characteristics

KANG Lei, LIU Haiyan, CHENG Weiying, CHEN Xiaohui, LI Jing

2022, 0(1):  8-14.  doi:10.13474/j.cnki.11-2246.2022.0002

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Studying the hot spot distribution of urban facilities is of great significance to grasp the current urban form. Traditional facility hot spot recognition methods tend to ignore the feature scale of facilities, focus on regional research, and lack a method system for accurately extracting facility hot spots. To solve the above problems, this paper proposed a method of hot spot recognition considering attribute characteristics,and takes the residential facilities in Beijing as an example. Firstly, the attribute values of facilities are used as weights to estimate the density value surface generated by weighted kernel density estimation, and the extreme points are extracted by using the extreme point detection model. Then use Getis-Ord G_i^* statistics for spatial autocorrelation analysis to generate statistically significant hot spots, and select extreme points to obtain hotspots. The experimental analysis shows that the method can accurately and effectively identify the hot spots of the facilities and make a reasonable classification, providing a diversified perspective for the research on the spatial layout of urban facilities.

Construction of ecological security pattern based on ecological importance assessment and minimum cumulative resistance model in Chongqing city

TAO Peifeng, LI Ping, DING Yi, LIU Jian, YANG Guangpu, XIAO He

2022, 0(1):  15-20,38.  doi:10.13474/j.cnki.11-2246.2022.0003

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The construction of ecological security pattern is an important way to ensure the stable operation of ecosystem and realize regional ecological security. This article takes Chongqing as an example, evaluates the ecological importance of Chongqing based on its ecological service functions and ecological sensitivity, and takes high-level areas of ecological importance and nature reserves as the ecological source. Six resistance factors, including elevation, slope, land use type,distance from road,distance from waterbodyand night light index, are selected from the ecological background and ecological stress to construct the ecological resistance surface of typical mountain animals, and the minimum cumulative resistance model (MCR) is used to simulate the potential ecological corridors, and then the urban ecological security pattern is constructed. The research shows that the ecological source area of Chongqing is 30 751.11 km², accounting for 37.32% of the total area of Chongqing, which is mainly distributed in the mountain forest land in the northeast and southeast of Chongqing. The identified 73 potential ecological corridors and 138 ecological nodes are superposed with ecological sources, and combining with the landscape pattern of Chongqing, a multi-level ecological security pattern of "two regions, three belts, four cores, multiple corridors and multiple points" was constructed, which provided scientific reference for ecological protection and restoration work in Chongqing.

Research on positioning of civil aviation aircraft based multi-sensor

WANG Mingjia, CHEN Haoxiang

2022, 0(1):  21-25.  doi:10.13474/j.cnki.11-2246.2022.0004

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In order to obtain the high-precision position of the civil aviation aircraft before landing, this paper discusses a multi-sensor-based high-precision positioning method for the civil aviation aircraft. During the flight of the aircraft, the onboard data logger will record the GPS receiver, radio altimeter, inertial navigation system and other sensor data during the entire flight; after the aircraft lands, use the radio altimeter data and GPS data for position difference, and then Further optimization using inertial navigation data can greatly improve the positioning accuracy before landing. The results show that the positioning accuracy is greatly improved two kilometers before the entrance of the airport runway, and the vertical positioning accuracy can reach the meter level, which can meet the needs of subsequent investigations.

Multi-source remote sensing image flood disaster information extraction and change analysis based on improved U-Net network

CHE Zijie, GAO Fei, WU Zhaofu, LI Zhenxuan

2022, 0(1):  26-32.  doi:10.13474/j.cnki.11-2246.2022.0005

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Information extraction and change analysis based on remote sensing images is an important method for detecting changes on the earth's surface, and it has a wide range of applications in urban planning, environmental monitoring, disaster assessment. SAR can penetrate clouds to achieve ground observation during floods, but side-view imaging will cause overlaps and shadows along with terrain undulations. DEM can provide elevation information of ground points, reflecting the undulations of the terrain, but cannot provide surface information. In order to achieve high-precision and high-efficiency extraction of disaster information for the disaster area and degree of the flood area, this paper proposes a change detection method based on U-Net fusion of multi-source remote sensing images. Experimental results show that disaster flood information with high spatial resolution can be extracted efficiently by the method performed in this paper.

Dynamic changes of main stream water area in the Yangtze River from Sentinel-1 remote sensing data

YAN Xiaqing, JIN Shuanggen, HUANG Minmin

2022, 0(1):  33-38.  doi:10.13474/j.cnki.11-2246.2022.0006

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This paper uses Sentinel-1 data to obtain the monthly water area of Shanghai-Yibin section from 2016 to 2020, and analyzes its annual and inter annual changes. The results show that:①Monthly variation rules is that January to May water surface variations are relatively stable, and the water area in June to August has gradually increased and is peak in July. It's falling slightly in September, and gradually decreases to stability after reaching the peak in October. ②Seasonal variation rules is that the waters in winter is the smallest area, the summer water area is the largest, It shows a significant seasonal difference in summer and winter. ③Endevelopment rules is that the trend in the water area after 2016 where the water area is relatively stable in 2017-2019, and is growing in 2020. In terms of segmentation, the water area is downstream with time to change from time to time, the range of which is biger than the middle's, and the middle's is biger than the upstream's, the upstream changes are relatively stable, and the downstream is more remarkable. ④It is prone to flooding, which mainly is distributed in a mid-range reaches, and it is necessary to pay attention to monitoring warning.

Estimating fractional woody/herbaceous cover based on multiple spatial data and air-ground co-sampling: taking East Asian steppe as an example

LIU Xu, ZHANG Ning, XU Xiaotian, AN Chao, XU Shixiang, LI Cheng

2022, 0(1):  39-43,55.  doi:10.13474/j.cnki.11-2246.2022.0007

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Fractional vegetation cover is the comprehensive description of vegetation growth, which is a base index for researching the interaction between global change and vegetation patterns. In this paper, we propose an approach for estimating fractional woody and herbaceous cover using multiple spatial datasets and air-ground co-sampling in East Asian steppe. Here are main conclusions:the accuracy of the estimation can be improved within the approach. The results of model evaluation show that the model is more robust when estimating woody cover. This method can response to sparse woody plants and be used for understanding the patterns and dynamics of vegetation cover in large grasslands.

Quantitative inversion of soil heavy metal Cd based on ensemble empirical mode decomposition

GUO Yunkai, CAO Xiao, XIE Xiaofeng, ZHANG Siai, XIE Qiong

2022, 0(1):  44-49.  doi:10.13474/j.cnki.11-2246.2022.0008

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In view of the lack of accuracy of the model for hyperspectral quantitative inversion of soil heavy metal content, this paper introduces the time-frequency analysis method seting ensemble empirical mode decomposition(EEMD) from the perspective of time-frequency space, and explores the application of EEMD method in hyperspectral quantitative inversion of soil heavy metal content.The EEMD method is used to decompose soil hyperspectral to obtain intrinsic mode function (IMF) components with different frequencies. By analyzing the correlation between IMF components and heavy metal content, characteristic spectra are extracted to construct an EEMD-SVM quantitative inversion model.The results show that the EEMD method can effectively extract the weak information in the soil spectrum.The determination coefficient R² of the EEMD-SVM model is 0.920 3, which is significantly higher than that of the SVM model based on the first-order differential processing of spectral data (0.786 6).It is explained that EEMD can be used as a new method of spectral treatment in the field of quantitative introspection of soil heavy metals.

High-precision pose estimation method for close range sequence images of cultural relic objects

HU Chunmei, XIA Guofang, ZHANG Xu, LIU Xi, WANG Wei, WEI Lixia

2022, 0(1):  50-55.  doi:10.13474/j.cnki.11-2246.2022.0009

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Aiming at the problem of pose estimation in 3D texture reconstruction of cultural relic image, this paper proposes a high-precision pose estimation method based on 3D data-driven and adjustment. Firstly, the accurate homonymous features are obtained through image feature extraction, matching and false matching point elimination. Then the high-precision pose relative relationship of the first pair of images is established, and the relative pose of the subsequent images is determined by combining the two-dimensional index driven by the 3D point data of the first pair of images. Finally, the high-precision image pose parameters are determined by beam adjustment and LM algorithm. The experimental results show that this method has certain advantages in determining the pose speed and pose accuracy, which lays the foundation for the subsequent generation of dense point cloud.

Performance analysis of BDS-2 precise point positioning augmented by BDS-3 within the Asia-Pacific region

MA Huilin, WU Wentan, WU Xiuli

2022, 0(1):  56-60.  doi:10.13474/j.cnki.11-2246.2022.0010

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BDS-2 satellite navigation system is mainly composed of GEO and IGSO constellation satellites. The geometric structure of the whole constellation changes slowly, which leads to a long convergence time when it is applied to precise point positioning(PPP). The construction of BDS-3 satellite navigation system will help to alleviate the above problems and obtain better positioning effect. In order to explore the enhancement effect of BDS-3 on BDS-2 PPP, this paper selects the 3 d observation data of 10 iGMAS stations located in the Asia-Pacific region, and first analyzes the support of three IGS analysis centers for BDS-3 precise products. Then, the positioning performance of static mode and simulated kinematic mode is analyzed. The results show that:①There are 9 BDS-3 satellites in the Asia-Pacific region can be observed. ②After applying BDS-3, the convergence time of static PPP is reduced by 40%, and the converged accuracy is improved by 46.5%. The convergence time of simulated dynamic PPP is reduced by 42.8%, and the accuracy is improved by 45.7%.

Response mechanism of terrestrial water storage to cumulative precipitation in Yunnan based on GPS vertical displacement

XIAO Jiahao, ZHANG Shuangxi, WEI Yu, CAI Jianfeng, HONG Min

2022, 0(1):  61-65.  doi:10.13474/j.cnki.11-2246.2022.0011

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Based on the global positioning system (GPS) vertical deformation data from CMONOC, the terrestrial water load deformation of six basins in Yunnan are calculated by principal component analysis, the correlation analysis and cross-wavelet analysis with precipitation show that the change of terrestrial water storage(TWS) has a lag of 1.5~2.25 months in the semi-annual cycle and 3~6 months in the annual cycle relative to rainfall in each basin. There is a significant negative correlation between TWS and cumulative precipitation due to the superposition of lags on different period. The days of cumulative precipitation in the six basins are different, ranging from 47 to 109 days. Based on the result, a response mechanism of terrestrial water storage to cumulative precipitation in Yunnan is proposed.

Accuracy evaluation of multi-GNSS broadcast ionospheric model

LIU Jialong, JIA Xiaolin, TAO Qingrui, FU Junsheng, ZHANG Fen

2022, 0(1):  66-71,78.  doi:10.13474/j.cnki.11-2246.2022.0012

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Ionospheric error is one of the main error sources for navigation and positioning, and broadcast ionospheric models provide a simple and effective method for single-frequency users to correct ionospheric delays. In this paper, the GIM product provided by CODE is used as the benchmark for evaluation, and the accuracy of four major broadcast ionospheric models is evaluated in various aspects, aiming to provide reference for subsequent model improvement and application. The results show that:the correction rate of each model is higher in the northern hemisphere than in the southern hemisphere, and the daytime correction rate is higher than that in the night. The NeQuick model has an average service performance in the middle and low latitudes, but is significantly higher than the BDSK8 and GPSK8 models in the high latitudes, and the correction rate is about 5% higher than that of the BDGIM model.The BDSK8/GPSK8/BDGIM model has the highest correction accuracy in the middle and low latitudes, and the correction in the high latitude band is The accuracy of BDSK8/GPSK8/BDGIM model is the highest in middle and low latitudes, and the correction rate of high latitude band is slightly worse. BDGIM model performs better than other models in general, and the global range correction rate can reach 76.91%.

LSTM geomagnetic positioning algorithm based on Attention mechanism in underground coal mine

YANG Yong, CUI Lizhen, GUO Qianqian, XUE Zhonghao

2022, 0(1):  72-78.  doi:10.13474/j.cnki.11-2246.2022.0013

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Aiming at the problem that the use of radio frequency signals for underground personnel positioning is greatly affected by the environment, this paper proposes an LSTM geomagnetic positioning algorithm based on the Attention mechanism. The mine smart phone is used to acquire underground geomagnetic data in the way of continuous acquisition of paths. By analyzing the characteristics of spatial difference and time stability of the geomagnetic signal changes in underground roadways, a geomagnetic fingerprint database oriented to the underground topology is established. The Attention mechanism is introduced into the LSTM model to enable which can be trained and given different weights according to the correlation between the geomagnetic sequence and the position; the geomagnetic data collected in real time downhole is input into the model for position estimation. The experimental results show that learning the mapping relationship between the geomagnetic sequence and the corresponding position through the neural network LSTM can effectively improve the positioning accuracy.

An improved MMF subsidence prediction model based on the Markov chain and its application

ZHAO Yahong, WNAG Weina, JIANG Peihua, LI Jiahui

2022, 0(1):  79-83.  doi:10.13474/j.cnki.11-2246.2022.0014

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Aiming at the complex and random characteristics of foundation settlement mechanism, an improved MMF settlement prediction model based on Markov chain theory is established. Firstly, the MMF model is fitted by CurveExpert software with some measured data. Then, according to the relative error predicted by the MMF model, the state interval is divided according to Markov theory, and the probability matrix of state transition is constructed to predict the state of the next settlement, thus the MMF prediction value improved based on Markov chain is obtained. Finally, the model is applied to the settlement prediction of shenzhen Binhai road municipal engineering soft soil subgrade, and the prediction accuracy of the model is analyzed. The results show that the prediction accuracy of the MMF model based on Markov chain is significantly higher than the MMF model. The modeling method is reasonable and can be used for similar engineering prediction.

A comprehensive geospatial data crowdsourcing task recommendation method

ZHANG Yuhang, ZHOU Xiaoguang, HOU Dongyang

2022, 0(1):  84-88.  doi:10.13474/j.cnki.11-2246.2022.0015

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Lack of data and volunteers in underdeveloped areas is the bottleneck that restricts global mapping task. In order to solve this problem, we propose a comprehensive geospatial data crowdsourcing task recommendation method to improve the effectiveness of limited volunteers' contributions. In this method, the research area is divided to several task areas using grids, the spatial preference is computed using triangular kernel and temporal preference is computed using exponential time forgetting rate, and TF-IDF is used to compute the semantic preferences of users. The spatio-temporal-semantics comprehensive preference is calculated using the multiplication rule. The initial task-user recommendation list can be obtained based on the spatio-temporal-semantics comprehensive preference. In order to improve the quality of the contribution data, the user reputationis introduce to our recommendation model, and the latent factor model is used to predict the user's reputation for each task area. The initial recommendation list is reordered according to the user's reputation. In order to verify the effectiveness of the method, we choose Islamabad (the capital of Pakistan) as research area because it is an underdeveloped areas with a certain data foundation. The user and crowdsourced data of Islamabad collected by the OpenStreetMap platform are used as the experiment data. The crowdsourced data is randomly divided into training and test set according to 8:2 ratio. The experimental results show that the proposed method in this paper can not only improve the acceptance rate of recommended tasks, but also can impove the quality of the contributions to some extent.

Comprehensive assessment of geological environment in the Beijing- Tianjin-Hebei region based on multiple index system

WANG Zhiyi, GUO Xuefei, YU Yang, WANG Na

2022, 0(1):  89-95,104.  doi:10.13474/j.cnki.11-2246.2022.0016

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Geological environment quality is an important factor affecting regional planning and construction. At present, the single evaluation index system is unable to evaluate the geological environment quality in the multi-geomorphic area reasonably and effectively. In order to study the evaluation method of regional geological environment quality suitable for multiple geomorphologic types, a multi-geological environment quality evaluation system based on two geomorphological types is established. The weight of evaluation indexes are obtained and the evaluation model of geological environment quality is established by using AHP and comprehensive index method. The evaluation of geological environment quality of the Beijing-Tianjin-Hebei urban agglomeration is carried out by means of spatial analysis technology. The results show that the spatial distribution of geological environment quality in Beijing-Tianjin-Hebei region is quite different. The distribution of geological environment quality in plain area is significantly affected by land subsidence, groundwater overexploitation and groundwater pollution. The distribution of geological environment quality in mountainous areas is obviously affected by active faults, topographic conditions and geological hazards. It is concluded that the evaluation of geological environment quality based on the multi-index evaluation system can reduce the interaction between the main evaluation indexes of geological environment quality of different geomorphological types, and the evaluation results can reflect the distribution characteristics of regional geological environment quality more reasonably and accurately.

Key technical problems on quality inspection of the land cover achievement of the natural resources survey and monitoring

CHEN Haipeng, ZHANG Li, LI Miao, XIE Wenjun, QIU Bo

2022, 0(1):  96-99.  doi:10.13474/j.cnki.11-2246.2022.0017

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As an important spatial data in the unified natural resources survey and monitoring system, the land cover achievement will play a fundamental supporting role for all kinds of natural resource survey and monitoring projects. Hence, data quality of the land cover achievement will be related to the correctness and reliability for the statistics, analysis and evaluation results of various natural resources. According to the practice of quality control of major survey and mapping projects, to ensure the quality of the final achievement, it is important to formulate scientific, reasonable and unified quality evaluation criterion for the achievement, and conducts comprehensive, efficient and accurate data quality inspection on the achievement. This paper analyzes current situation of quality inspection and evaluation for the land cover achievement in some typical ongoing natural resources survey and monitoring projects, such as the geographical conditions monitoring project and the national land survey. Furthermore, this paper discusses uses quantitative index evaluation method for the quality evaluation criterion, using latest intelligent remote sensing image information extraction technologies for quality inspection of the classification accuracy, and uses latest remote and enhanced field verification method for the field quality inspection of the land cover achievement, which can provide technical references for quality control of the unified natural resources survey and monitoring.

Underwater structure safety assessment of estuary sluice based on 3D sonar point cloud

FENG Lu, LI Yan, XI Siyuan, ZHENG Xiaodong

2022, 0(1):  100-104.  doi:10.13474/j.cnki.11-2246.2022.0018

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The estuarine sluice underwater structure safety has a great significance on the safeties of the sluice engineering, the river course and surrounding residents. In the low-visibility water environment, the traditional safety detection method of underwater structures based on artificial diving is very inefficient. In order to improve the efficiency, 3D scanning sonars have been widely applied on the safety evaluation of important underwater structures. In this paper, the BlueView BV5000 3D scanning sonar is used for the underwater structure safety evaluation of the estuary sluice on Suzhou River. Based on the measured data, the underwater structure safety is evaluated by using the processed 3D sonar point cloud after data filtering and splicing. The sonar evaluation results verified with manual inspection prove the advantages of 3D scanning sonar in underwater structure safety assessment, and further provide the data basis for subsequent maintenance.

Multi-source remote sensing monitoring and prediction of urban expansion in typical coastal zone: a case study of Qingdao

LI Peng, LI Chu'an, YANG Jimei, LI Zhenhong, WANG Houjie

2022, 0(1):  105-109.  doi:10.13474/j.cnki.11-2246.2022.0019

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In this paper, DMSP-OLS and NPP-VIRS nighttime light as well as Landsat multi-spectral remote sensing images are utilized for quantitative analysis of built-up area, urban boundary shape and extension trend in Qingdao over the past 25 years. Combined with the land use classification, road network, POI, DEM and multi-source driving factors and CA-Markov model, land use classification in Qingdao in 2027 is simulated and predicted. The results show that in the past 25 years, the expansion of built-up areas in Qingdao is mainly extensional, and the other urban areas generally expand along the direction of Jiaozhou Bay, and converge to the main urban area of Qingdao, and the construction land in the main urban area develops to the northwest. This paper verifies the applicability of nighttime light remote sensing in monitoring and predicting typical coastal urban expansion, which is expected to provide an important reference for the management and decision-making of urbanization development process.

Fusion of UAV image and LiDAR point cloud to study the detection technology of mountain surface cover landscape characteristics

GAO Sha, YUAN Xiping, GAN Shu, YANG Minglong, YUAN Xinyue, LUO Weidong

2022, 0(1):  110-115.  doi:10.13474/j.cnki.11-2246.2022.0020

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Airborne LiDAR data can accurately provide three-dimensional spatial location information of objects, and UAV high-resolution image has rich color information and texture information. By integrating the advantages of two kinds of data expression, data integration and fusion are carried out. Aiming at the matrix landscape of the most widely distributed vegetation cover type in mountainous areas, this paper proposes to construct visible vegetation index (VDVI) and then carry out the research on the typical vegetation feature extraction of the fusion spectral information point cloud data based on this technology. In order to verify the accuracy of the method, three data sources are constructed and the mountain is carried out in turn. The experiment of vegetation extraction in the area. The qualitative and quantitative analysis of the experimental results shows that the vegetation coverage rate of the fusion spectral point cloud data is 56.8%, which is closer to the reference value of 58.2% than the other two data types. The credibility is relatively high, the effect is better, the vegetation patch contour is clearer, and it is more suitable for the target object vegetation feature extraction, so that the advantages of the fusion image information point cloud data classification can be reflected. The feasibility of this classification method for mountain vegetation feature extraction is discussed.

Effect of high-resolution image fusion algorithm on the classification precision of land utilization in coastal wetland

GAO Yu, HU Zhaoling, FAN Ru

2022, 0(1):  116-120.  doi:10.13474/j.cnki.11-2246.2022.0021

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Aiming at the problem that the fusion algorithm has a significant impact on the accuracy of image classification, this paper chooses the coastal wetland of Lianyungang Liezi Estuary coastal zone as the research area, and GF-1 satellite image is used as data source. Three fusion algorithms, Gram-Schmidt, PCA and Brovey are used to fuse images. After that, on the eCognition software platform, based on the object-oriented multi-scale segmentation technology, the image is classified by random forest algorithm, and evaluate the accuracy of the classification result. Experimental results show that the image quality after Gram-Schmidt fusion algorithm is the best, and the classification accuracy of Gram-Schmidt algorithm is the highest; Brovey fusion algorithm has good spectral fidelity for vegetation and water body,after changing the band combination, the classification accuracy of Brovey algorithm is obviously improved; the accuracy of PCA algorithm is the lowest among the three fusion algorithms.

Application of air ground multi-data mutual auxiliary fusion technology in reconstruction of large-scale ancient buildings

SUN Baoyan, ZHOU Xin, QIN Yucheng, WEI Longhua, GE Guanghao

2022, 0(1):  121-127,132.  doi:10.13474/j.cnki.11-2246.2022.0022

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In view of the characteristics of the large-scale ancient buildings, such as narrow and high single building, flexible decorative components, single modeling technology is difficult to establish a comprehensive electronic file of the three-dimensional model of the large-scale ancient buildings. In this paper, Yueling "Xiaoyi Kefeng" memorial archway in Yueling village, Guanyang county, northern Guangxi is taken as the research object, and a three-dimensional model reconstruction method based on air ground multi-data mutual auxiliary fusion is proposed. With the help of oblique photography and three-dimensional laser scanning, and the ground close range multi-perspective photography as the auxiliary collection scheme, a complete and fine three-dimensional model electronic file of large-scale ancient architectural relics is reconstructed, and the data processing fusion deviation verification, model integrity analysis and accuracy evaluation before and after data fusion is completed. This method can provide a new idea for the establishment of large-scale ancient building archives, and has a wide application prospect in the development of cultural relics protection.

Application of generated high-precision DEM in key reservoir region of Henan province based on airborne LiDAR

GAO Shengchao, GAO Yantao, WANG Wenjie

2022, 0(1):  128-132.  doi:10.13474/j.cnki.11-2246.2022.0023

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This paper takes seven reservoirs in Henan province as research objects to obtain the image-free LiDAR cloud data and orthophotomy data in the reservoir region. A total of 47 sorties are flown with a total area of 950 km², the reservoir protection line of 2442 km and the management line of 1886 km.This paper discusses the selection of equipment, setting of flight parameters, equipment checking, filtering of point cloud data, point cloud refinishing, accuracy checking and other links.The results show that the method has the advantages of high accuracy and low cost compared with traditional methods.The method provides a new way to obtain data for delimitation and fine management of reservoir region boundaries.

A vulnerability detection method for airborne LiDAR data

LI Haolin, LI Chong, WANG Hui, SHE Yi

2022, 0(1):  133-138.  doi:10.13474/j.cnki.11-2246.2022.0024

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Airborne LiDAR equipment is susceptible to terrain undulations, flight heights, specular reflections and other factors, which leads to holes in LiDAR data. Moreover, if the holes are not detected or processed, it will seriously affect the production and application of LiDAR data. In view of this, this paper uses the position and attribute information of the point cloud, based on the equal-scale shrinkage and point cloud rasterization algorithm to detect the vulnerability areas in the airborne LiDAR data, and then supports the quality detection of the LiDAR data and the supplementary scanning of the vulnerability areas. Experimental results show that the vulnerability area detected by this method is complete and accurate, and the proportional reduction algorithm reduces the influence of terrain fluctuations on the vulnerability detection accuracy compared to the equivalent reduction algorithm, which is more scientific and reasonable.

Assessment of forest ecosystem service value accounting in priority area of biodiversity protection in Anji county of geography census

ZUO Shilei, JIN Shanshan, GU Xiaoqin

2022, 0(1):  139-144.  doi:10.13474/j.cnki.11-2246.2022.0025

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Forest ecosystem provides human beings with ecosystem services and biodiversity which is one of the most key factor of restricting ecosystem services.Taking the priority area of biodiversity conservation in Anji county as a pilot area, this paper analyzes the connotation and accounting system of ecosystem service value at home and abroad. For calculation of the key difficulties and problems, in order to reasonable accounting system, operational model, data access and parameter settings science for the principle,it builds to applie to Anji county of forest ecosystem service value accounting theory methods, implementation of biodiversity conservation priorities in Anji county area ecosystem service value of quantitative calculation of space. The results show that the total value of forest ecosystem services in the biodiversity priority areas in Anji county in 2018 is 6.537 billion yuan, and the value of forest ecosystem services per hectare is above 80 000 yuan.

The application of geodetic surveying time system in APP encryption

LI Cunwen, HAO Bo, DENG Xuefeng, WANG Ningtao, ZHU Rui, WANG Ruyi, ZHU Qi

2022, 0(1):  145-148.  doi:10.13474/j.cnki.11-2246.2022.0026

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Information security is related to the vital interests of developers and users. How to encrypt software or application program is particularly important. In this paper, a combined encryption method based on MD5 and Julian day is proposed by using geodetic time system. Firstly, the unique ID of APP machine is obtained, and then the validity period of app is calculated by combining Julian day. Secondly, the user name is salted, and finally the information is extracted MD5 algorithm is used to calculate the password, and the specific encryption process is given. This method not only realizes the effective encryption of app, but also can finely control the service life, which greatly protects the rights and interests of developers and users.

Measurement and positioning precise calculate method for automatic guidance system of active articulated shield machine

DONG Weidong, GUO Hao, LUO Haibo, MA Quanming

2022, 0(1):  149-154,158.  doi:10.13474/j.cnki.11-2246.2022.0027

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The active articulated shield machine is widely used in curved tunnel excavation. The precise calculation of its shield posture is the core function of the automatic guidance system of the shield machine, and it is also the premise and foundation for the real-time deviation correction of the shield machine in shield construction. The current situation of shield machine automatic guidance system providers at home and abroad keeping their own shield machine positioning calculation principles and methods secret has brought great difficulties to shield machine positioning manual review and shield construction. Based on the study of two domestic shield machines and the prism method automatic guidance system of the Japanese calculus workshop, a precise positioning calculation method for the active articulated shield machine is proposed by using the principles of solid geometry and spatial projection transformation, and the detailed calculation formula is given. Through the calculation and comparison of multiple sets of positioning coordinate data of multiple shield machines in different tunnel lines, the correctness of the precise calculation method of shield posture is verified.

High-precision road map making method and key technology

XU Jie, HOU Fei, CAO Guanghang

2022, 0(1):  155-158.  doi:10.13474/j.cnki.11-2246.2022.0028

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This paper describes a high-precision road map acquisition method based on multi-source data such as vehicle-borne mobile mapping system and oblique photogrammetry system, and makes in-depth research on key technologies. Zibo intelligent network test base, the first test section of intelligent network expressway based on automatic driving in China, is taken as an example to carry out multi-source data acquisition such as laser point cloud, panoramic photo, tilt image and high-precision road map elements acquisition. This method is based on the automatic extraction of road 3D vector elements, supplemented by manual collection and compilation, and BeiDou data is tested in the data difference calculation. The example shows that this method is feasible and reliable, effectively improves the high-precision road map acquisition mode, reduces the labor intensity, ensures personal safety, and improves the operation efficiency, which is of great reference value for the production of high-precision road map.

Analysis on the construction of surveying and mapping big data center under structural reform on supply side: a case of geospatial big data center in Shaanxi province

YANG Hongshan, BAI Mu, LI Junfeng

2022, 0(1):  159-163.  doi:10.13474/j.cnki.11-2246.2022.0029

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Under the requirements of high-quality development, there are several supply-side problems, such as decentralized IT infrastructure, "isolated" data resources and production capacity bottlenecks. The geospatial big data center in Shaanxi promotes the supply side structural reform of surveying and mapping through three stages of work. Firstly, IT infrastructure construction and upgrading realizes intensive utilization and flexible allocation. Then, data resource transformation and sharing makes sure big data analysis and open interconnection. Thirdly, industrial chain upgrading and efficient supply aims to on-demand renewal and service. The utilization rate of hardware resources of the big data center is close to 99%. The big data center has played an important role in improving quality and efficiency in geography national condition monitor, national GNSS reference station network adjustment, the third national land resource survey, etc.

Wuhan pilot mid-term practice and thinking of national new fundamental surveying and mapping construction

XIAO Jianhua, LI Pengpeng, LI Haiting, CHEN Kai, CAO Wentao, CHEN Tao

2022, 0(1):  164-167.  doi:10.13474/j.cnki.11-2246.2022.0030

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Wuhan officially became the first pilot city for national new fundamental surveying and mapping construction approved by the Ministry of Natural Resources in January 2019. After two years of exploration and construction, the Wuhan pilot focused on the goals and tasks and carried out the physical transformation and upgrading of the basic geographic database. In terms of transformation and upgrading of product system, technical system, organization management system and standard system, Wuhan pilot has initially formed phased results that can be used for reference throughout the country. With the continuous deepening of pilot construction, the ideological understanding of new fundamental surveying and mapping in various regions and units is gradually improving. Some key issues and difficulties still require in-depth thinking, joint research, and consensus formation in the next stage of construction work for the whole country and the entire industry, so as to promote the comprehensive construction of the country's new fundamental surveying and mapping system with high quality.

Design and practices of experiential teaching mode oriented for training of new engineering talents in geomatics

LI Jun, ZHANG Chengye, DAI Huayang, CHEN Wei, YAN Yueguan, DU Shouhang, ZHAO Hengqian

2022, 0(1):  168-172,176.  doi:10.13474/j.cnki.11-2246.2022.0031

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From its early focus on surveying and mapping, geomatics has developed to uidely serve the national economy in all walks of life. At the stage when the engineering education is shifting to the construction of new engineering disciplines, the traditional teaching mode can no longer meet the requirements for training new engineering talents in geomatics. This article designs the training mode of new engineering talents for geomatics, with imparting objective knowledge as the core, reshaping the content and form of activities for teachers, students and knowledge, forming a five-stage experiential teaching mode embedded by teacher designing, student experiencing, and teacher-student interaction. It is applied to the course teaching of geomatics in our university, and the teaching practice is carried out on four types of knowledge contents:conceptual, law, relational and comprehensive application. The practice shows that this teaching mode has the value of popularizing and is helpful for students to understand the knowledge deeply and improve their ability.

Construction and practice of GNSS undergraduate training system which contains “prospective, innovative and practical characteristics”

HUANG Guanwen, ZHANG Qin, WANG Li, ZHANG Shuangcheng, QU Wei, LI Xin, WANG Le, LI Xiaofei

2022, 0(1):  173-176.  doi:10.13474/j.cnki.11-2246.2022.0032

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With the construction and promotion of Chinese BDS project, GNSS problems become more professional, informational and intelligent. Solving complex navigation problems has gone beyond the field of single curriculum knowledge. And students need to have innovative capabilities such as exploration frontiers, cognitive discovery, practical application. So it is urgent to cultivate innovative talents in satellite navigation. According to the characteristics of satellite navigation innovative personnel training, the paper puts forward and constructs a GNSS undergraduate training system which contains prospective, innovative and practical characteristics. The system is based on the characteristics of the college's geologic industry; inspire students' cutting-edge thinking in teaching; combines disaster application to drive applicationinnovation in competition; based on BDS laboratory and school enterprises to carry out innovative and entrepreneurial training in practice.After more than ten years of teaching practice, it has cultivated a group of satellite navigation innovative talents with distinct characteristics and outstanding practical ability in the industry, which good teaching results have been achieved, and have certain promotion and application value.