Table of Content

25 December 2022, Volume 0 Issue 12

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The analysis of object-oriented fine modeling

LI Jiajun

2022, 0(12):  1-6.  doi:10.13474/j.cnki.11-2246.2022.0348

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In this paper, the idea of object-oriented fine modeling is proposed by using the technology of photo and point cloud fusion, and practices and explores a landscape sketch from three stages:data acquisition, data processing and model production. Through comparison, the advantages and disadvantages of data obtained by different types of sensors in the model results are analyzed. Finally use the point cloud and photo fusion modeling technology, the problem of rough geometry and poor texture of the real scene model is solved. It provides reference basic data for small-scale planning.

Augmented visualization analysis for 3D geological models based on visual cues and variable combinations

LI Zhihong, ZHU Qing, WU Xuequn, GUO Yongxin

2022, 0(12):  7-13.  doi:10.13474/j.cnki.11-2246.2022.0349

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Visualization and visual analytics can improve the human perception of data. However, the visualization of 3D geological models is hindered by environmental elements such as the ground surface, which interrupts visual clues of the underground local space. The irregular geometric characteristics of 3D geological models also increase the difficulty of interactive analysis, and make it difficult for users to perceive and analyze the spatial and attribute characteristics of geological elements and inter-elements. In order to solve this problem, this paper proposes an augmented visualization analysis method for characteristics information of 3D geological models. This paper focuses on the combinations of multiple visual variables and monocular visual cues to achieve enhanced expression of key information and quantitative analysis of 3D geological models. The area geological units of a bridge and a tunnel in Sichuan-Tibet railway are selected for case study. The experiment results show that, compared with the existing 3D grid scale visualization analysis methods, the proposed method improves the analysis accuracy and efficiency by 13.63% and 29.32%, respectively. According to the statistical analysis of the participant survey, the proposed method also greatly improves the visualization effect and interaction experience. The proposed method can perceive and analyze the key characteristics information in complex 3D geological models more efficiently.

Realize building monomerization of 3D model based on deep learning

WANG Wenna, ZHANG Gong, WU Kan, WANG Rui, QI Lizhuang

2022, 0(12):  14-18,23.  doi:10.13474/j.cnki.11-2246.2022.0350

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The oblique photography 3D modeling technology can quickly obtain the real 3D model of the target area, but the model under this mechanism is a continuous triangulated irregular network(TIN), which makes it impossible to analyze specific geographic objects. In this paper, two methods of object-oriented image analysis and deep learning semantic segmentation are used to extract buildings and comparative analysis. The result shows that semantic segmentation method can effectively extract the buildings in the digital orthophotos corresponding to the tilt model. By post-processing the extraction results and giving the vector data the basic attributes of the building, the vector datas are used to realize the building monomerization and publish 3D models and data services, which can more effectively use the oblique photography model to show the geographical space and the building information.

Application of close to photogrammetry and BIM technology in component level 3D real scene construction of endangered ethnic buildings

CAI Jun, JIANG Wei, WEN Riqiang, FENG Shengfeng

2022, 0(12):  19-23.  doi:10.13474/j.cnki.11-2246.2022.0351

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In order to improve and perfect the 3D real scene of traditional villages so as to achieve the purpose of inheriting and protecting the endangered ethnic buildings in traditional villages. Relying on the component level 3D real scene project of traditional villages in Guangxi, this paper uses the oblique photogrammetry to build the urban level 3D real scene of traditional villages, and uses the close photogrammetry and BIM to build the component level 3D real scene model of highly endangered ethnic buildings. The component level 3D real model map of traditional villages is a combination of oblique photography model and close photogrammetric model. According to the relevant information of the endangered ethnic buildings, including the appearance characteristics of the components, size information, endangered level, age and geographical location, this paper uses BIM technology to carry out parametric modeling, coding and warehousing, forming a searchable 3D real model database.

Research on automatic hole repair method based on 3D modeling of UAV tilt photography

XIE Wenjun, ZHANG Jialiang

2022, 0(12):  24-28,34.  doi:10.13474/j.cnki.11-2246.2022.0352

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Aiming at the problem of holes in the process of constructing real 3D scene by tilt photogrammetry, this paper looks for a method that can realize the automatic repair of holes. Through the compiled boundary shrinkage method processing program and using the spatial three processing results of tilt photogrammetry, the automatic hole repair of real 3D model is realized. Through the actual 3D modeling project of UAV tilt photography, the hole repair test is adopted to verify that the automatic hole repair method is feasible, and the model still has high a ContextCapture Centeruracy after hole repair.

A method of simplification of 3D model based on CityGML

NI Xiaodong, LIANG Junda, WU Longxiang, LIU Muyang

2022, 0(12):  29-34.  doi:10.13474/j.cnki.11-2246.2022.0353

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3D real scene should meet the needs of managing natural resources, society and economics, which puts forward making basic geographic information products entitize. The simplification of 3D model is the key link of the transformation. Based on the experience of existing methods, this paper proposes a simplification method for 3D model based on CityGML. Based on two-dimensional vector of the solid profile of the figure vertex coordinates and elevation information, build polygons for walls, roof, etc. Combine the polygons into a simple three-dimensional expression. Then Texture map with Render to Texture technology (RTT), build 3D model for each two-dimensional vector by refactoring semantics and LOD levels based on CityGML. This method can successfully make 3D model entitize which occupies a small capacity, and meets various application demands of 3D real scene.

Image measurement technique for building deformation monitoring

WEI Yi, XU Yebo, ZHANG Wei, XIE Shaomin, WANG Jimin

2022, 0(12):  35-41.  doi:10.13474/j.cnki.11-2246.2022.0354

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This paper designs a new set of algorithms to locate centers of artificial marks pictured from long distance in an outdoor environment, and applies it to complete the building deformation monitoring tasks. This paper aims at pixel-level edge positioning and data quality control. It firstly proposes the maximum gradient projection notation to obtain the pixel-level edge of a mark. An improved edge thinning method is then presented and the curvature is introduced for further screening. A novel pixel-level edge positioning process is formed based on the above three steps to achieve a complete and accurate thinning edge and also able to avoid interferences from outdoor condition. A data quality control mechanism is then designed based on the statistical theory after the sub-pixel center localization. Only those localization results which meet the statistical requirement are kept to participate in the final calculation. The negative effects caused by the shaking of the imaging equipment can thus be controlled. Experiments are conducted in various environment with different background and photographic ranges. The results prove the image measurement method presented in this paper shows its advantage in stable and accurate localization capability, fast processing speed, low requirement for imaging equipment, and strong adaption to outdoor environment. Using a mainstream SLR camera with a standard lens, its positioning accuracy is less than 3.5 mm within 200-meter photographic range and therefore can be used in real building deformation monitoring scenarios.

Visual SLAM algorithm based on improved CoHOG

YU Yao, SUN Xinzhu, GUO Junyang, CHEN Mengyuan

2022, 0(12):  42-50.  doi:10.13474/j.cnki.11-2246.2022.0355

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The mobile robot has a large amount of calculation, long running time and low accuracy of matching in the closed-loop detection link of SLAM. So this paper improves the CoHOG closed-loop detection algorithm, improves the HOG descriptor in the algorithm to GDF-HOG descriptor, to enhance image characteristics and improve the efficiency of image feature extraction. Before the matching process, GDF-HOG global rough matching is added to reduce the number of visual templates and improve the computational efficiency of the algorithm. After the matching process, region of interest (ROI) position matching is added for testing to reduce false positives of closed-loop detection and improve accuracy.Finally, the closed-loop detection algorithm proposed in this paper is combined with RatSLAM, and tested in open data sets and real environments. The test results show that the proposed algorithm has advantages in the accuracy of closed-loop detection and adaptability to the environment.

Optimization of ground-based SAR data and analysis of disaster body area early warning and prediction

LIU Yuxi, YANG Fengyun, QIN Hongnan

2022, 0(12):  51-56,96.  doi:10.13474/j.cnki.11-2246.2022.0356

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Aiming at the problems that it is difficult to identify the ground-based SAR abnormal data, the development characteristics and laws of potential landslide mass are not obvious, and it is difficult to estimate the critical sliding area, this paper introduces the processing method of ground-based SAR deformation data based on the landslide data of a mine in Gansu province. The abnormal deformation data are effectively identified, screened and eliminated by Matlab software, and distinguished by color differences, which further highlights the evolution law of potential disaster body area in different stages. Based on the principle of ground-based radar monitoring, a polygon area estimation method is proposed. This method can estimate the area of potentially hazardous areas. Study on velocity reciprocal curve group with unequal period treatment, it is found that the inverse square method of velocity can further amplify the characteristic trend. The early warning result is accurate and the prediction effect is good through this early warning and prediction method, which provides a new idea for realizing the early warning and prediction of mine landslide.

Analysis of evapotranspiration estimation and its spatial-temporal characteristics: taking Zhanghe irrigation district as an example

ZHANG Di, WEI Zheng, FENG Tianquan, CHEN Zumei, WANG Fengjing, HUANG Kui

2022, 0(12):  57-63.  doi:10.13474/j.cnki.11-2246.2022.0357

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Regional scale accurate inversion of evaporation for water cycle, climate change, scientific irriga-tion and drought and flood monitoring research has important scientific significance, this article taka Zhanghe irrigation district as typical irrigation area, builds the SEBS model of remote sensing evaporation, verifies the accuracy of re-mote sensing evaporation, the temporal and spatial law of evaporation is analyzed. The results show that:① the average correlation coefficients between ET observation values and simulated values at zhongxiang, jingmen and tuanlin stations from 2009 to 2018 are 0.86, 0.84 and 0.83 respectively, and RMSE valu-es are 0.61, 0.67 and 0.62 mm/d respectively. The interannual variation of ET observed and simulated values is less than 10%, the correlation coefficient ranges from 0.7 to 0.9, RMSE ranges from 0.4 to 0.8 mm/d, and standard deviation ratio ranges from 0.8 to 1.5. ② The average value of ET in the study area from 2009 to 2018 is 427.34 mm, and ET shows an overall upward trend.③ The time series of ET and precipitation at annual, seasonal and monthly scales are consistent. ET is higher in northeast and southwest and lower in west at multiple time scales. The research results can better present the high spatio-temporal heterogeneity of ET and the spatial differences of ET between years. This study will provide scientific basis for the development and management of water resources and scientific irrigation in Zhanghe irrigation district.

Precision analysis of aerial photogrammetry assisted by BeiDou PPK technology

WANG Jing, WANG Zhaoyang, ZHANG Feng, ZHAO Xianren, GU Xianghui, JI Cheng

2022, 0(12):  64-69.  doi:10.13474/j.cnki.11-2246.2022.0358

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Due to the limitation of network signal and baseline length, the commonly used GPS real-time kinematics (RTK) technology cannot be applied to UAV aerial photogrammetry in areas such as the Arctic and Antarctic, offshore islands or reefs. Moreover, GPS is not our autonomous satellite navigation system, and cannot ensure permanent safety and reliability. To solve these problems, this article explores the use of our self-built BDS-3 to assist UAV photogrammetry through dynamic post-processing (PPK) technology. Taking DJI Phantom 4 RTK UAV as an example, the paper carries out PPK process of UAV POS data with BDS-3, GPS and BDS-3+GPS combined observation values. Then it analyzes the effects of different navigation satellite sources on the horizontal and elevation precision of UAV aerial photogrammetry in the absence of ground control points. The results show that after PPK calculation of the UAV POS data with BDS, GPS and BDS+GPS combination, the horizontal positioning precision is improved from decimeter level to centimeter level, and the elevation precision is improved from meter level to decimeter level or even centimeter level, which is equivalent to that of setting five ground control points. UAV aerial photogrammetry assisted by BDS PPK technology is able to meet the accuracy requirements of 1:500 scale aerial triangulation encryption precision in plain area.

Comparison of measurement methods and accuracy evaluation of shallow gully in the Yuanmou Dry-Hot valley

ZHAO Yakai, DENG Qingchun, LIU Hui, YANG Haiqing, YANG Feng, WANG Yumeng

2022, 0(12):  70-76,83.  doi:10.13474/j.cnki.11-2246.2022.0359

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In order to explore the accuracy of different measurement methods to obtain shallow gully data, taking the shallow gully in the Dry+Hot valley area of Yuanmou as an example, the shallow gully data is obtained by various measurement methods such as RTK, 3D laser scanning, close-range photogrammetry and other measurement methods, DEM is established and the morphological parameters of the shallow gully are extracted, and the difference between the DEM is established after the close-range photogrammetry is obtained in different ways after obtaining the marker coordinates, and the accuracy of the shallow gully cross section is obtained by comparing and analyzing different measurement methods. The results show that the DEM established by RTK with low density point data is coarser and only reflects the general trend of the gully margin. The DEM elevation measured by the close-range photogrammetry RTK method is lower than the DEM elevation obtained by the close-range photogram total station. The shallow gully morphological parameters extracted by the 3D laser scanner and the close-range photogrammetry total station are more accurate. The cross-section close-range photogrammetry total station measurement and the measured cross section coincidence is higher compared with the shallow gully cross section. The analysis shows that the close-range photogrammetry total station method, as a shallow gully measurement method, has great advantages in terms of accuracy and efficiency.

Refined DEM generation based on fusion of laser point cloud and image point cloud

DAI Huayi, LI Shoujun, ZHANG Ziwei, YANG Fanlin, MAO Donghai, CHEN Xiang

2022, 0(12):  77-83.  doi:10.13474/j.cnki.11-2246.2022.0360

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In view of the problem that the ground laser scanning and UAV aerial photography technology is difficult to obtain the complete point cloud data of the area to be measured due to factors such as field angle limitation or occlusion in actual field measurement, based on the classical ICP algorithm, this paper proposes a fusion method of laser point cloud and image point cloud considering the elevation difference and point cloud density, divides the point cloud into blocks by differential digital elevation model, selects the fusion range based on the point cloud density, and registers the segmented image point cloud to the holes and sparse areas of the laser point cloud. The method in this paper can improve the fusion effect of laser point cloud and image point cloud, keep the precision of laser point cloud and retain more detailed features, and realize the high-quality fusion of laser point cloud and image point cloud.

Vertical accuracy evaluation of DEM data based on ICESat-2 ATLAS

DING Xiameng, ZHANG Jixian, GUO Jing, ZHANG He, CHANG Yaru

2022, 0(12):  84-90.  doi:10.13474/j.cnki.11-2246.2022.0361

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In order to investigate the elevation accuracy of three open source DEM data, ASTER GDEMV3、SRTM1 DEM and AW3D30 DEM. In this paper, high precision ICESat-2 ATLAS altimetry data is used as reference data, comparative evaluation of elevation accuracy of DEM using GIS statistical analysis, error correlation analysis and mathematical statistics.The results show that:①The quality of AW3D30 is the most stable; SRTM1 DEM has the highest accuracy in the plains; the accuracy in the highland mountains is AW3D30 DEM, ASTER GDEMV3, and SRTM1 DEM in descending order.②The elevation accuracy of DEM data is influenced by the surface coverage and is closely related to the topographic factors. The performance of DEM data elevation accuracy in the two study areas with the same surface coverage is not consistent, SRTM has the best performance under the plain surface coverage with an average error of 3.15 m, and AW3D30 DEM has the best performance under the mountainous surface coverage with an average error of 7.61 m.③The influence of slope on the elevation accuracy of DEM data is large, and the elevation error of three kinds of DEM data in two study areas increases with the increase of slope; the influence of slope direction on the elevation accuracy of DEM data is small, and no obvious pattern is found.

Ultra-wideband indoor positioning algorithm based on MCS-SCKF

ZHANG Mei, Lü Le, CHEN Wanli, FENG Tao

2022, 0(12):  91-96.  doi:10.13474/j.cnki.11-2246.2022.0362

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Aiming at the nonlinear tracking problem in traditional ultra-wideband (UWB) indoor positioning, this paper proposes a new positioning algorithm based on the current statistical (CS) model and volumetric Kalman filter (CKF). The localization algorithm uses singular value decomposition (SVD) to replace the Cholesky decomposition in the standard CKF algorithm to improve the robustness of the algorithm, constructing a singular value decomposition volumetric Kalman filter (SCKF). The functional form of the test parameters is obtained firstly, and the improved CS model (MCS) is obtained to realize the adaptive adjustment of the model parameters; then the MCS model is introduced into the SCKF filter to realize the adaptive adjustment of the filtering algorithm; finally, the MCS-SCKF algorithm can be used to The UWB positioning system model which is solved to obtain the moving target position. Simulation and experimental results show that the algorithm is superior to CS model-Kalman filter algorithm (CS-KF) and CS model-SCKF algorithm (CS-SCKF), and improves the positioning accuracy of UWB indoor positioning.

Multi-factor LiDAR point cloud segmentation simplification algorithm

SHI Zhiyuan, XU Weiming

2022, 0(12):  97-101.  doi:10.13474/j.cnki.11-2246.2022.0363

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Excessive density of point clouds leads to data redundancy, making it difficult to calculate, store, and display point cloud data. Aiming at the problem of simplifying point clouds in LiDAR terrain scanning, this paper proposes a multi-factor segmentation point cloud simplification method. Firstly, on the basis of improving point cloud organization method, the variation coefficient weighting method is used to synthesize four traditional point cloud feature extraction factors to obtain the final comprehensive evaluation factor. Then feature points and non-feature points are distinguished by the final factor. Secondly, the improved octree is used to divide all the points into subsets based on their location and the point number, and determination on whether to retain some of the non-feature points are made according to the number of feature points in each subset. This method can evaluate and select the characteristics of the data more comprehensively and objectively to obtain the most representative points, and achieve more precise simplification. The experiment shows that the error of the results of the multi-factor segmentation method is 20% to 50% lower than that of other methods, and the accuracy is 5% to 70% more uniform in the overall test area, which proves that the proposed method is superior.

Estimation and validation of inter-frequency clock bias on GPS/BDS triple signals

ZHANG Gaojian, ZHAO Qile, TAO Jun, GUO Jing, LI Zhen

2022, 0(12):  102-109.  doi:10.13474/j.cnki.11-2246.2022.0364

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In three-frequency GNSS data analysis, a systematic deviation named as inter-frequency clock bias (IFCB) arises due to the inconsistent frequency reference of clock products. Using data from 80 globally MGEX stations and 100 regionally CORS stations in China on day of year 153-160 in 2021, the epoch will be brought in differences of IFGF combinations are formed to realize a estimation of IFCB and analysis of the time-varying characteristics further. Finally, the estimated IFCB is applied to the undifferenced and uncombined PPP. The results show that the IFCB of GPS BLOCK Ⅱ-F with an amplitude up to 14 cm is larger than that of GPS BLOCK Ⅲ and BDS (generally less than 5 cm). For PPP validation, the GPS positioning accuracy has improved significantly with considering IFCB. The phase residuals of GPS/BDS-2/BDS-3-IGSO at the third frequency L5/B2I/B2a are reduced by 59.42%, 24.66%, and 16.00, respectively, and The point accuracy of GPS, BDS-2/BDS-3-IGSO, GPS/BDS-2/BDS-3-IGSO improve by 56.55%, 29.16%, and 20.72% in kinematic mode.

Analysis of path optimization algorithm using seagull theory

ZHANG Tao, YANG Xiaofeng, QIN Kun, LI Feifei, LUO Wenshan

2022, 0(12):  110-115.  doi:10.13474/j.cnki.11-2246.2022.0365

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Aiming at the path optimization problem that needs to be solved frequently in GIS spatial analysis, this paper studies a new type of swarm intelligent space path optimization algorithm, called seagull optimization algorithm (SOA). By redefining the representation and update strategy of seagull position, the seagull optimization algorithm is converted from continuous domain to discrete domain, and then the discrete seagull optimization algorithm is established(DSOA). At the same time, in order to make the seagull to jump out of the local optimal value, a random variable factor is introduced. In order to verify the reliability of DSOA, by defining the fitness function and feasible solution space, the discrete seagull optimization algorithm is used to solve the traveling salesman problem(TSP). The results experimental results show that DSOA has good robustness in solving optimal path problems and has strong application potential in spatial analysis.

Geographical detection of the allocation and influencing factors of different healthcare resources: take the main city of Guiyang as an example

LI Wei, DU Fangjuan, RUAN Ou

2022, 0(12):  116-120,125.  doi:10.13474/j.cnki.11-2246.2022.0366

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The healthcare is greatly related to the health and well-being of the residents, but previous studies have more often focused on hospitals, ignoring the other health resources allocation and spatial correlation, such as pharmacies and clinics. This paper takes the main city of Guiyang as an example, field surveys to investigate different medicine systems such as different level public hospitals, private clinics and pharmacies, and researches the variability and factors in the spatial distribution of urban healthcare by using spatial analysis methods, such as kernel density and geographic detector.The results show that, the spatial allocation of healthcare in the main city of Guiyang is characterized by dense inside and sparse outside, forming a spatial structure of "one center, one belt, and multiple points". "One center, one belt" means public medical resources hierarchical agglomeration patterns, especial the different level public hospitals, such as the secondary and tertiary medical institutions, and ‘multiple points’ means the community hospitals, the private clinics and the pharmacies homogeneous distribution patterns. The spatial allocation of health resources is significantly influenced by factors such as residential land use, road density and population density, but there are differences in the influencing factors for different types of health resources.

Automated sample generation strategy for winter crop mapping: a case study in Lanling county

XIAO Fangfang, ZHANG Hongyan, HE Wei, ZHANG Liangpei

2022, 0(12):  121-125.  doi:10.13474/j.cnki.11-2246.2022.0367

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Accurately obtaining the spatial distribution of crops is a prerequisite for crop growth monitoring and yield prediction. At present, automatic acquisition of crop distribution is still a challenge because the processing of remote sensing image is time-consuming and the collection of sufficient training samples is laborious. How to obtain sufficient training samples in an efficient and economical way has become one of the key factors in crop mapping. By combining the phenological characteristics of winter crops with Sentinel-2 time series images, this paper proposes an automated sample generation strategy for winter crop mapping. Firstly, the normalized difference vegetation index (NDVI) time series curves are used to identify winter crops. Secondly, the differences between unknown samples and standard green chlorophyll vegetation index (GCVI) time series curves are calculated through the curve similarity measurement method, so as to assign the correct label to the unknown samples. Finally, the Random Forest model is trained with the obtained samples, which realizes the extraction of winter crops in the study area. In the final accuracy evaluation result, the overall accuracy (OA) is 98.46% and Kappa is 0.973, which shows the effectiveness of this method to realize the quick automatic winter crop mapping.

An improved method for segmentation of supervoxel and regional growing point clouds

HAN Ying, ZHENG Wenwu, ZHAO Sha, TANG Yuran

2022, 0(12):  126-130.  doi:10.13474/j.cnki.11-2246.2022.0368

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Point cloud segmentation is a key processing step for identifying spatial features of geographic scenes, exploring and recording spatial information, and its segmentation accuracy directly affects the effects of subsequent 3D scene reconstruction and feature extraction. Aiming at the instability of traditional region-growing point cloud segmentation algorithms, this paper combines supervoxels and region-growing algorithms to segment point cloud data, and uses the color information of the point cloud itself to further improve the segmentation results. The experimental results show that compared to the traditional region growing and existing segmentation algorithms, combining supervoxels and region growing algorithm proposed in this paper has better effect on point cloud data segmentation, and its accuracy and recall rates are both improved.

Matching method of heterologous stereo image pairs based on deep learning

DUAN Yunshan, WU Xianwen, WANG Ruirui, SHI Wei, LI Yiran

2022, 0(12):  131-135.  doi:10.13474/j.cnki.11-2246.2022.0369

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Compared with stereo matching of homologous images, there are great differences in spatial features, field angle and resolution between the heterogenous images acquired by UAV tilt photography and close-range photography, which bring difficulties to image matching. In this paper, the feature points are extracted by using the convolutional neural network based on homography transformation, and the graph neural network with cross-attention mechanism is used to match the feature points in the matching stage. It overcomes the problem of poor matching effect caused by large disparity and distorted transformation between different images. In this paper, Ma jiacitang in Dacheng county, Langfang city, Hebei province is taken as the experimental data, and the matching effect of traditional SURF (accelerated robust feature) algorithm and deep learning algorithm is compared. The results show that the algorithm based on deep learning has a higher matching rate for heterologous images with large perspective differences.

Construction and application of monitoring index for mine ecological restoration

YUE Yongsheng, LUO Zhiyuan, JI Lin

2022, 0(12):  136-140.  doi:10.13474/j.cnki.11-2246.2022.0370

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At present, there is a lack of a complete monitoring index system for the monitoring of mine ecological restoration project effect in China. In order to promote the construction of mine ecological restoration monitoring index system, this research builds a set of scientific evaluation index system of mining ecological restoration results monitoring technology from the basic content of mine ecological restoration monitoring, the aspect such as the selection of monitoring indicators research, innovation from water environment, soil environment, the surface environment and geological environment, ecological restoration comprehensive benefit. The index system is applied in the ecological restoration monitoring of a coal mine in Shenmu city, Shaanxi province, and verified by means of GIS analysis and sample monitoring. On this basis, the overall effect of mine ecological restoration is evaluated. The results show that among the soil environmental indicators, the soil layer thickness index reflecting soil physical properties are better. The surface water pollution of the mining area is less, and there is basically no microbial and organic pollution. The water quality is alkaline, which is consistent with the soil in the mining area. The vegetation cover and habitat quality index in the test area are good. The proportion of subsidence area is small. The comprehensive benefit index of mine ecological restoration in the experimental area is not good.

Road and bridge disease detection system based on UAV

GOU Yongtao, LI Wenbo, DUAN Xuefeng

2022, 0(12):  141-146,169.  doi:10.13474/j.cnki.11-2246.2022.0371

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In view of the problems of low efficiency, high cost, omission in the scope of human detection, and safety of manual operation in bridge disease detection, this paper designs and implements a road and bridge disease detection system based on UAV cruise, which has the functions of autonomous obstacle avoidance, road and bridge disease detection, and autonomous cruise positioning. At the same time, a desktop control system with visual integration function has been developed, which is organically combined with the cloud service platform to make the operation more intuitive and convenient. Monitoring information can be mapped and updated in real time, providing a technical data basis for road and bridge asset management and disease detection.

Automated production solutions from existing topographic maps to geo-entities

ZOU Lei, YNAG Peng, CAO Wentao, XIE Gangsheng

2022, 0(12):  147-152.  doi:10.13474/j.cnki.11-2246.2022.0372

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Presently, new fundamental surveying and mapping are carrying out around the country. Among them, one of the most significant process is producing geo-entities from existing topographic map. This paper introduces the principle and process of transforming topographic maps into geo-entities, and proposes a method to automatically produce geo-entities from existing DWG data and topographic map database. We are carrying out data production experiments on iData software to verify the feasibility of this process. This paper summarizes the requirements of processing methods and statistics the automation efficiency of the whole process. Futhermore, we analyze the factors which may affect the efficiency of automation and operating few methods to improve the efficiency of automation. This paper has certain reference significance for producing geo-entities from the existing topographic maps.

Progress and topical analysis of international coastal zone research in the last 30 years based on knowledge mapping

LIU Xiaoding, TANG Liming, LI Yili, XU Minduan, KANG Xinyi, SUN Duan, LI Yuchen, XIAO Hong, ZHAO Yaolong, CHEN Weilian, Lü Fengtao

2022, 0(12):  153-159.  doi:10.13474/j.cnki.11-2246.2022.0373

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With the accelerated of urbanization, the environmental problems of coastal zone areas are becoming more and more obvious, and the research related to them has become the focus of scholars. Based on the Web of Science database, this paper identifies information such as countries and keywords as the object of study. Application of Citespace's knowledge mapping to sort out the history of coastal zone related research, and to analyse it quantitatively and visually. By concluding the research topics and evolution process in different periods, it helps to improve the research related to the coastal zone and provides reference and reference for future research direction and perspective. As the result shows, more and more researchers are devoting themselves to the study of coastal zones as the specificity of their status is recognised. We have identified the application of big data and cloud computing technologies as well as studies targeting sea level rise at large scales, urban ecology-related studies of coastal zones at medium scales, and LiDAR bathymetry at smaller scales as the main research directions for the future.

Study on geological disaster-prone zoning in Shaoxing city

LUO Guangfei, GONG Yingying, QIAN Chao, XIAO Han, ZHENG Libo, WANG Zhaoyuan, ZHANG Jintao, YE Linghao, LIU Yunbo

2022, 0(12):  160-164,169.  doi:10.13474/j.cnki.11-2246.2022.0374

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In order to quantitatively assess the geological disaster risk, with the help of GIS software, Shaoxing city is divided into grids, and the evaluation index system and index evaluation model of geological disaster risk are constructed in this paper. Through the quantitative evaluation of geological disasters in Shaoxing city, the vulnerability degree of geological disasters in Shaoxing city is finally divided into four grades:high, medium, low and not easy, and the zoning achievement map of the vulnerability of geological disasters in Shaoxing city is drawn. The research results support the "14th five-year plan" of Shaoxing city geological disaster prevention and control, and serve Shaoxing city geological disaster prevention and control management and decision-making.

High-accuracy survey of roller coaster steel structure and data application of local coordinate system

XU Xiaoyu, LIU Quqian

2022, 0(12):  165-169.  doi:10.13474/j.cnki.11-2246.2022.0375

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The conventional method of coordinate decomposition calculation based on manual operation is not efficient and there may be erroneous judgement due to human fallibility in responseing to the gradually increasing construction requirements and the needs of special products application. In this paper, the problem of data correction and qualification evaluation in the dimensional accuracy control for the construction of the complex structures similar to "roller coaster" is effectively solved with the help of automatic coordinate decomposition and redirection, which has accumulated a comprehensive experience of project application in the high-accuracy surveying, inspection and deviation corrections for the similar complex spatial steel structures.

Acquisition, processing and quality analysis of 1-meter spacing point cloud data in the pilot area of national new basic surveying and mapping system construction

ZHU Lei, ZHANG Jie, LI Ran, ZHAO Fei, LIU Yang

2022, 0(12):  170-173.  doi:10.13474/j.cnki.11-2246.2022.0376

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The production of terrain-level geographic scene is one of the important tasks of Shandong pilot project of national new basic surveying and mapping system construction. As the main component of topographic-level geographic scene, DEM is generally produced by airborne LiDAR point cloud data. The surveying mapping institute of the author in is as a pilot area, and uses Leica CityMapper to obtain the point cloud data with aspacing of less than 1 meter, tests the flight quality and point cloud quality, and checks the point cloud vertical and horizontal accuracy. The Gaomi LiDAR project verifies the accuracy and efficiency of Leica the City Mapper, and it provides a technical solution for 1-meter spacing point cloud data acquisition and processing for Shandong land aera, and provides a guarantee for DEM and terrain-level geographic scene production.