Table of Content

25 August 2021, Volume 0 Issue 8

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Automatic power line extraction algorithm in complex scene

ZHAO Yanfeng, HU Yaogai, WANG Xianpei, ZHAO Le

2021, 0(8):  1-6.  doi:10.13474/j.cnki.11-2246.2021.0231

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End-to-end power line extraction from aerial images in complex scenes is the key to power line detection by UAVs. In this paper, an automatic power line extraction algorithm based on improved Mask R-CNN is proposed by analyzing the problems existing in the realization of power line instance segmentation based on deep learning. First of all, according to the linear characteristic of power line, this paper puts forward a kind of improved Mask R linear IoU calculation method, a CNN original IoU calculation, improve the performance of power line extraction. Then the improved network on the power line data set for training, power line crude extraction results. Finally through a line marshalling fitting method, the result of the crude extract clustering fitting, to solve the problem of power line breakage and misdetection. Experimental results show that the proposed method can accurately extract the complete power lines from UAV aerial images with complex environment.

Aerial LiDAR building point-cloud progressive extraction algorithm

GAO Zhimei, WANG Jingxue, SHEN Zhaoyu

2021, 0(8):  7-13,36.  doi:10.13474/j.cnki.11-2246.2021.0232

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Aiming at the problem that is easily affected by adjacent vegetation, a building point-cloud progressive extraction algorithm is proposed in this paper for airborne LiDAR. Firstly, the ground point-clouds and the non-ground point-clouds are distinguished by using the cloth simulation filter. Next, the initial building point-clouds are extracted by using Otsu to get threshold to segment the non-ground point-clouds on the basis. Then, DBSCAN is used to eliminate outlier noise points on the initial building point-clouds through the connectivity of the point-cloud. Finally, the edge of the building is obtained through the Alpha Shape algorithm. The experimental selectes three sets of LiDAR point-cloud dates of different type of urban building provided by the ISPRS official website. The result shows that the algorithm of this paper can achieve the extraction of airborne LiDAR building point-cloud better.

Scene classification of high-resolution remote sensing image based on multi-kernel SVM using features extracted from LDCNN

GENG Wanxuan, ZHOU Weixun, JIN Shuanggen

2021, 0(8):  14-21.  doi:10.13474/j.cnki.11-2246.2021.0233

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Due to the problem that the feature dimension of convolutional neural network is high and the single-layer feature cannot accurately express the complex semantic information of high-resolution remote sensing image, a scene classification method of the low dimension of convolutional neural network (LDCNN) based on multi-kernel SVM is proposed in this paper. Firstly, the pre-trained convolutional neural network is modified into a low-dimensional network structure. Then, different high-level features extracted from the low-dimensional network is performed to find the corresponding optimal kernel function via SVM classification using different kernel functions, and these multiple optimal kernel functions are fused into a new composite kernel. Finally, multi-kernel SVM classification is carried out. Experimental results show that the proposed method has low feature dimension, and can combine the advantages of features extracted from each layer via multi-kernel SVM, thus achieving more than 99% classification accuracy on two benchmark datasets. In addition, the experiment also proves that this method has strong transfer learning ability.

Ground penetrating radar data reconstruction combined with regularized K-SVD and Hampel filter

YAN Kun, ZHANG Zhihua, YAN Luchun

2021, 0(8):  22-27.  doi:10.13474/j.cnki.11-2246.2021.0234

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To alleviate the energy difference between the GPR data caused by topographic relief, and ensure the accuracy of the GPR image interpretation and recognition, this paper proposes a GPR data reconstruction method combining regularized K-SVD dictionary learning and Hampel filtering algorithm. In the experiment, regularized K-SVD dictionary learning is used to carry out the energy balance of GPR signals, Hampel filtering algorithm is used to eliminate the outliers of the balanced signals, and two-dimensional visualization of the balanced signals is carried out, so as to complete the image reconstruction of the GPR. The comparison experiment shows that this method can not only balance the original GPR signal, but also the balanced signal is more in line with the GPR signal propagation law, which can guarantee the quality of the trace data signal, and the reconstructed image is better, which has a good practical value in the GPR image reconstruction.

Real-time stitching of unmanned vehicle images based on GA-SIFT algorithm

WANG Yan, QI Meng

2021, 0(8):  28-32,47.  doi:10.13474/j.cnki.11-2246.2021.0235

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In order to realize the real-time splicing of unmanned aerial vehicle images, the key technologies in aerial image stitching of an unmanned aerial vehicle are deeply researched in this paper. To solve the problem of time-consuming in the process of feature point matching, an image mosaic algorithm based on genetic algorithm optimization is proposed. Firstly, the SIFT algorithm is used to extract the feature points of the image. In the process of feature point matching, the Euclidean distance is used as the similarity measurement, and the genetic algorithm is used to optimize algorithm. Then the RANSAC algorithm is used to remove the mismatched points to complete image stitching. Experiments show that GA-SITF algorithm greatly reduces the matching time, which is proportional to the number of feature points, and at the same time improves the matching accuracy, thereby improving the real-time and robustness of image stitching.

Point cloud filtering algorithm based on windowing and terrain slope in densely-vegetated area

MA Tao, YANG Xiaoming, YAN Yueguan, YAN Dongchuan

2021, 0(8):  33-36.  doi:10.13474/j.cnki.11-2246.2021.0236

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The three-dimensional laser scanner obtains the point cloud data of the classic landform, which needs to be filtered to remove the ground vegetation. Because the point cloud is dense or occluded in densely-vegetated areas, the ground points are very few, and the terrain surface cannot be fitted. This part of the vegetation points is difficult to remove. Aiming at the characteristics of the point cloud data of densely-vegetated areas, this paper proposes a point cloud filtering algorithm for densely-vegetated areas based on windowing and terrain slope. It is considered that the higher point of the two adjacent points of the elevation difference caused by non-terrain slope is non-ground point. The test results show that this algorithm can well remove low vegetation points in densely-vegetated areas, retain real ground points, and improve the processing accuracy of point cloud filtering in densely-vegetated areas.

Analysis of the difference between landscape surface area and vertical projection area in the Hengduan Mountains: a case study of Yajiang county

LIU Xingyu, ZHOU Guangsheng, Lü Xiaomin, REN Hongrui

2021, 0(8):  37-41.  doi:10.13474/j.cnki.11-2246.2021.0237

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The topography of the Hengduan Mountains is complex. When vertical projection area is used to represent landscape surface area for quantitative calculations, large errors will occur. Taking Yajiang county in the middle of the Hengduan Mountains as an example, the landscape surface area of each land use type in Yajiang county is calculated by the geological significance of the surface roughness based on DEM data and surface cover product data sets. And the difference between landscape surface area and vertical projection area is analyzed. The results show that the differences between surface area and projected area in Yajiang county positively correlate with the DEM resolution, and negatively correlate with altitude. The main factor affecting the differences between the surface area and the projected area is the slope. As the slope increases, the differences and the growth rate of the differences also increase. The differences between surface area and projected area are diverse because of the different land use types.

Spatial sampling of population based on multi-source information and deep learning feature extraction

CHUN Jin, ZHANG Xinchang, GUO Haijing, ZHANG Jianguo, JIN Shicheng

2021, 0(8):  42-47.  doi:10.13474/j.cnki.11-2246.2021.0238

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Population sampling survey is a means to estimate the population of a region through population samples. Due to the spatial difference of population distribution, the traditional sampling survey theory is difficult to meet the growing demand of spatial sampling. The research on reasonable and efficient population spatial sampling survey method is of great significance to population statistics, human activities and urban problems. This paper proposes a population spatial sampling method based on multi-source information and deep learning feature extraction. Firstly, we use quadtree segmentation for stratified sampling with the help of impervious surface information, initially select the survey samples that may have population distribution.Secondly, we estimate building density of sample by convolution neural network that is a common model of deep learning to assist in the final sample selection and survey scheme formulation. The results show that this method can effectively screen the sampling areas closely related to population distribution, eliminate a large number of useless samples, improve the efficiency of population survey and save a lot of survey costs.

Extraction and analysis of feature elements of micro-topography in southern margin of Dinosaur Valley

LUO Weidong, GAN Shu, YUAN Xiping, GAO Sha

2021, 0(8):  48-54.  doi:10.13474/j.cnki.11-2246.2021.0239

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Topographic feature information is an important basis in geoscience research. It is used to describe the overall appearance of topographic transformation and determines the basic landform and topographic features. This paper qims at the research on the extraction and analysis of topographic features of the annular micro-topography on the southern edge of Lufeng Dinosaur Valley. Firstly, the drone survey technology is used to obtain the image data of the survey area, and the 0.5 m resolution DOM data and point cloud data of the survey area are constructed through image data processing. Based on the Terra solid software platform, the filter rules are built to classify the point cloud data, dilute and compress, extract the ground points in the survey area, and use the ground point data as the basic data to construct DEM data with a resolution of 2 m in the survey area. Then, by superimposing the maximum value extraction and positive and negative terrain extraction in ArcGIS spatial analysis, the extraction and analysis of terrain feature points are completed; combined with the hydrological analysis in ArcGIS and the combination of plane curvature and slope type, the extraction and analysis of terrain feature lines are completed. Finally, an object-oriented method is used by eCognition9.0 to realize the extraction of terrain features. The test results show that: ① The best analysis window for extracting saddle points is 11×11; ② The ridge-valley line is extracted by saddle point positions and two methods. Among them, the hydrological analysis extracts the ridge line that is more detailed and the overall coherence. It is prominent and the saddle points that are extracted from the densely distributed ridges on both sides of the mountain and the rugged mountain in the experimental area. It shows that the southern edge of Dinosaur Valley is affected by the subtropical low-latitude plateau monsoon climate as a whole, and the mountain is weathered and eroded to a certain extent; ③ The topography of the southern edge of Dinosaur Valley among the characteristics, bare rock and bare land account for a relatively large area. Combining the dry and wet climate characteristics of the field and the relatively low vegetation actually is surveyed, which shows to a certain extent that the surface soil in this area is loose, and the attention should be paid to ecological problems caused by soil erosion.

Matching method for road networks considering geometric features and topological continuity

QIN Yuluo, SONG Weidong, ZHANG Zaiyan, SUN Xiaorong

2021, 0(8):  55-60.  doi:10.13474/j.cnki.11-2246.2021.0240

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The existing road network matching methods still need some human intervention and control, and do not achieve automatic matching. Moreover, for the data with certain scale differences, there may be some mismatches in the matching results, due to the influence of unrelated road objects. In view of the above problems, this paper proposes a hierarchical matching strategy from rough matching to fine matching considering geometric features and topological continuity. In the rough matching stage, the short side median Hausdorff distance is used to calculate the similarity of the matching objects, and then the nearest neighbor analysis results of the end points of the road network arc segment are used as the matching threshold to determine whether the matching object is the same name entity. In the fine matching stage, the discrete entities with the same name in the evaluation results of the rough matching stage are constructed as a complete road stroke, that is, the false matching is eliminated and the missing matching is added by tracking. The proposed algorithm is verified by the road networks with different scales in Sucheng district. Experimental results show that the algorithm has good matching effect, which is conducive to the realization of matching automation.

Recent progress of the three-dimensional coordinate datum modernization in the United States

XU Wei, Lü Zhiping, LI Linyang, KUANG Yingcai, WANG Fangchao, YANG Kaichun

2021, 0(8):  61-64,92.  doi:10.13474/j.cnki.11-2246.2021.0241

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With the development of geodetic technology and the increasing demand for high-precision reference system, the National Geodetic Survey(NGS) plans to modernize the National Space Reference System (NSRS). This paper mainly introduces the reason of using plate fixed reference frame, and summarizes the basic strategy and characteristics of the three-dimensional coordinate datum modernization according to the blueprint for 2022. Comparing with the existing NAD83, the new datum is mainly improved as follows: ① Adopting the strategy of “plate fixed”, the number of plate reference frames is increased from 3 to 4. ② The reference frame mainly relies on active control points(CORS), and passive control will be reduced to secondary access. ③ The intra-frame velocity model(IFVM) will be provided. In addition, the Euler pole and IFVM need to be further determined.

High-precision navigation and positioning method with limited error divergence algorithm under closed environment

WANG Xiaojing, TANG Chao, WANG Yong, HOU Haiqian, YANG Xiaofei

2021, 0(8):  65-68,73.  doi:10.13474/j.cnki.11-2246.2021.0242

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The navigation accuracy of navigation and positioning devices based on GNSS system is limited in closed or blocked environment. Therefore, improving indoor positioning accuracy and getting rid of GNSS dependence is a current research hotspot. Aiming at this problem, this paper studies the LiDAR+IMU+DMI multi-source sensor navigation and positioning technology. By bringing the LiDAR control target data into the Kalman filter equation, the error state vector of the IMU+DMI combination is calculated, and the error dispersion is limited, so as to obtain the high-precision position of the device. This technology can make the mobile measuring equipment completely get rid of the dependence on GNSS signal, realize the accurate positioning of the mobile measuring equipment in underground closed space, and facilitate the detection of underground space. Experiments on a subway in Wuhan show that the proposed algorithm is suitable for high precision navigation and positioning of mobile measuring equipment without GNSS signal in underground and indoor enclosed environment.

Application of static leveling automatic measurement technology in subway tunnel structure monitoring

LIU Xinyu, WANG Yong, TANG Chao

2021, 0(8):  69-73.  doi:10.13474/j.cnki.11-2246.2021.0243

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At present, the settlement of subway tunnel structure is mainly measured manually by leveling instrument.This monitoring method not only has low work efficiency, consumes a lot of manpower and material resources, but also can not achieve all-weather monitoring. Traditional manual monitoring can not meet the real-time monitoring requirements during subway operation.To solve this problem, this paper introduces the automatic static leveling measurement technology, through the deployment of static leveling gauges on the subway tunnel track bed, real-time monitoring point data is obtained from the remote control terminal, realizing the whole process monitoring during the construction of the tunnel structure protection area, and provides guarantee for the safety of the tunnel structure during the construction period. This article analyzes the actual engineering application cases and the monitoring results in the project. The results show that this technology realizes the automatic leveling of subway tunnels and provides technical support for the safety of subway operations.

Analysis on the deformation law of the cross-river shield tunnel of Wuhan metro line 4 in flood season

ZHAO Lifeng, TANG Chao, WANG Li, WANG Yong

2021, 0(8):  74-77.  doi:10.13474/j.cnki.11-2246.2021.0244

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In this paper, based on the engineering background of the intensive monitoring of the Wuhan metro line 4 cross-river tunnel during the flood season in 2020, the project analyzes the ring-by-ring monitoring data of the entire section of the cross-river tunnel by applying the ring-by-ring monitoring data measured by the three dimensional laser shield structure and determines the key monitoring intervals. Three round-by-ring encrypted monitoring data discussions in key monitoring intervals illustrate the trend of convergence changes caused by the continuous rise of the water level of the Yangtze River. Combined with the distribution of manual monitoring points and data characteristics, it shows that there are many blind areas in traditional manual monitoring. When we focus on absolute position changes, which makes the tunnel structure relative changes in morphology to be ignored. The cross-river tunnel is located in a complex geographical and geological environment, and the three dimensional laser ring-by-ring monitoring in flood season provides an effective guarantee for the safe operation of the tunnel.

Analysis of intelligent identification algorithm for shield tunnel cracks based on high-definition industrial camera

LI Zihao, TANG Chao

2021, 0(8):  83-87,101.  doi:10.13474/j.cnki.11-2246.2021.0246

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Cracks have always been the key detection object of tunnel diseases, but it can only be found by the naked eye and then recorded through the traditional manual inspection. The accuracy and efficiency of manual identification completely depend on personal experience judgment, without the assistance of information technology, so the identification accuracy of operation efficiency needs to be improved. In order to solve the above problems, with the help of high-definition industrial camera imaging by high resolution, fast acquisition speed and other characteristics, the high-definition industrial camera is deployed on the rail car to obtain the tunnel surface crack disease information, which greatly improves the efficiency of tunnel crack recognition, and improves the recognition accuracy by 0.2 mm. At the same time, the optimized cascade R-CNN algorithm is integrated to train tunnel crack samples under supervision. At the same time, we develop a set of crack disease identification route from hardware data acquisition, data processing software and data management platform, which really broke the technical barriers of slow identification, low accuracy, relying on experience and difficult management.

Research and application of automatic detection of rail fastener damage

HOU Haiqian, TANG Chao, ZHAO Lifeng, ZHANG Hao

2021, 0(8):  88-92.  doi:10.13474/j.cnki.11-2246.2021.0247

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The traditional fastener inspection basically adopts manual inspection method, which not only has the disadvantages of low work efficiency and high labor intensity, but also has the disadvantages of many human factors interference and low inspection sampling rate. To solve these problems, this paper proposes a method for detecting damage and loosening of rail fasteners based on a line structure light sensor, and develops an intelligent monitoring system for rail fasteners to realize detecting damage automatically. Finally, the research results are applied to the detection of rail fasteners in a subway section of Xuzhou city, and the method is verified with feasibility and accuracy, which provides a new method for the inspection of subway track fasteners.

Study on space distribution and correlation of shield tunnel diseases in urban rail transit

XU Pengyu, TANG Chao, WANG Li

2021, 0(8):  93-96,110.  doi:10.13474/j.cnki.11-2246.2021.0248

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The urban rail transit in China has entered a period of equal emphasis on construction and maintenance. With the increase of the service life of subway tunnel, the variety of tunnel diseases has been increased, and it shows a trend of gradual aggravation. Based on three-dimensional laser ring-by-ring monitoring, the spatial distribution characteristics and autocorrelation of the damage in the tunnel are studied. It is the premise of tunnel disease prevention and control to master the operating state and disease development trend of subway tunnel. Ring-by-ring 3D laser measurement data of a subway tunnel are used to analyze the spatial distribution characteristics of the disease such as dislocation, falling blocks, cracks, lining split along the route. Also, this paper analyzes the relationship between the disease and the surrounding geological environment. The self-correlation between diseases is studied by using gray correlation analysis algorithm which provides a quantitative analysis method for understanding the development trend of tunnel diseases and the coupling relationship between the diseases. The research in this paper provides an effective basis for understanding the spatial distribution of tunnel diseases, predicting the occurrence and treatment of tunnel diseases, and providing a strong guarantee for the safe operation of the subway.

Point cloud data processing based on helical laser scanning system

DONG Zhinan, SHI Peihao, GAO Han

2021, 0(8):  97-101.  doi:10.13474/j.cnki.11-2246.2021.0249

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Due to the advantages of high speed, flexibility and high resolution, helical laser scanners have been widely used in subway tunnel detection systems. However, existing data processing schemes have large synchronization error and low rate of data utilization. We propose a method to improve the accuracy of localization and make full use of the point cloud data. The starting point of the uniform motion of the car is calibrated, and the navigation speed is updated only when exceeding the upper limit, which is determined by the noise of the tunnel road. Meanwhile, the 360° panorama used for disease monitoring is firstly generated from point cloud data to improve the user interaction. Results show that the positioning error is 4.2 mm in 50 m, which is superior to the existing schemes. The generated panorama provides a new developing direction for disease monitoring in subway tunnels.

Road entity fusion method based on multiple similarity features

ZHOU Xiuhua, LI Naiqiang

2021, 0(8):  102-105,157.  doi:10.13474/j.cnki.11-2246.2021.0250

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With the acceleration of the pace of urban construction and the expansion of the application field of basic geographic information, the national economic construction and people’s life have an increasing demand for basic geographic information, which also puts forward higher requirements for the current situation and update frequency of basic geographic information. Therefore, it is of great significance to study the geographic information data fusion technology with different accuracy and different sources. Road entity is an important basic geographic information, especially railway, expressway, national and provincial road, urban trunk road. This paper focuses on the road entity, studies the differences between data, establishes automatic matching evaluation index, and builds homonymous matching, change detection and incremental updating model based on FME platform, realizes the automatic updating and fusion of road entity, and shortens the updating cycle of road entity Period. The second round of the 13th five year plan basic surveying and mapping update project uses this technology to complete the integration of important road entities. Through analysis and verification, it proves the feasibility and accuracy of the technology, and provides technical support for the construction of new basic surveying and mapping system.

Generative adversarial network super-resolution reconstruction for single remote sensing image

HAN Zhisheng, SUN Pichuan, TANG Chao

2021, 0(8):  106-110.  doi:10.13474/j.cnki.11-2246.2021.0251

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The process of using low resolution (LR) images to predict the corresponding high resolution (HR) images is called image super-resolutions, which aims to get a clear image. With the vigorous development of artificial intelligence, image super-resolution reconstruction has more and more applications in many fields such as medical treatment and remote sensing. This article learns to use the deep learning model of generative adversarial networks (GAN) to perform single-image super-reconstruction. Compared with traditional methods, this model proposes a new perceptual loss function, including an adversarial loss and a content loss. The adversarial loss distinguishes the generated image from the actual high-resolution image by training the discriminator network structure, while content loss uses the pre-trained VGG19 network model to calculate the perceived similarity of image features, rather than the similarity in pixel space. The experiment proves that the introduction of generative adversarial network into single-image super-resolution, MOS score is higher than traditional methods. This article will focus on the principles, effects, and applications of SR and GAN.

High-precision and fast detection for the shape of ice pipe in super-large speed skating area

CHEN Limin, FAN Tingli

2021, 0(8):  111-114.  doi:10.13474/j.cnki.11-2246.2021.0252

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The National Speed Skating Oval is the world’s first super-large ice surface cooled by carbon dioxide, covering an area of about 12 000 square meters. The high-precision installation of the ice pipe is very important. The traditional measurement method evaluates the overall situation of drainage through 30% spot check and discrete sampling check. Three-dimensional laser point cloud data can extract the spatial location information of each tube, and detect the installation of refrigeration tube more comprehensively. In this paper, a three-dimensional laser operation method based on multi-target ball prism is proposed, and two new algorithms are proposed, the warpage detection method and the parallelism detection method of the tube. This method provides an important basis for the construction, operation and maintenance of the National Speed Skating Oval. This method can be used as a reference for specific building construction detection.

The key technology of large-scale channel reality 3D modeling

WEN Guanghua, OU Yanghui, CHEN Guang

2021, 0(8):  115-118,143.  doi:10.13474/j.cnki.11-2246.2021.0253

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The traditional channel surveying and mapping information management and fusion technology is insufficient, and it is difficult to fully reflect the impact of the natural geographical environment, facilities and buildings on the water safety. Aiming at the problem of damage and missing of the reality 3D model of waterway, this paper introduces a multi-scale level set image segmentation method, that automatically initialized with the buffer image of hole, so as to obtain the accurate channel water area range by fast iterative segmentation, and further restrict the reality 3D model reconstruction and model singleization. This method is verified in the construction task of reality 3D channel map of Wangjiatan demonstration section of Yangtze River in Changshou District, Chongqing. Compared with the traditional model repairing and singleization method, the experimental results show that the technical method proposed in this paper is effective, which significantly improves the optimization efficiency of reality 3D model of waterway, and supports the safety management of waterway operation.

Application of RGB-D SLAM technology for indoor high-precision 3D mapping

FAN Junlin, XIAO Bin, TU Liping, HU Quanyi, SHI Xianjie, WEI Shuangfeng

2021, 0(8):  119-122.  doi:10.13474/j.cnki.11-2246.2021.0254

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High-precision 3D mapping is an important support for indoor 3D mapping. 3D mapping based on 3D LiDAR scanning technology is costly, requires the advance arrangement of targets, is prone to incomplete data in complex indoor environments, takes a long time to model 3D reconstruction based on image sequences, and is susceptible to a variety of factors. To address these problems, this paper applies RGB-D SLAM technology to indoor high-precision 3D mapping. By combining the depth camera with SLAM technology, the camera poses are calculated and 3D spatial information is recovered to obtain indoor 3D point cloud models, and the dense point cloud accuracy is evaluated with the actual measurement of the target object as the benchmark. The experimental results show that the method can quickly obtain high-precision 3D point cloud models with low cost and high efficiency, which can well meet the application requirements.

Key technology of dynamic high-precision construction measurement in National Speed Skating Oval and its application

LI Jiulin, XU Hao, TANG Chao

2021, 0(8):  123-128,165.  doi:10.13474/j.cnki.11-2246.2021.0255

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The irregularity, diversity, complexity and large scale of the building structure of the National Speed Skating Oval bring great difficulty to the construction measurement. The research and application of dynamic high-precision measurement technology is an important foundation to realize the high-precision lap of various professions and links in the construction process. The key technology of dynamic and high-precision construction measurement in National Speed Skating Oval has solved the technical problem of the difficulty of synchronous tensioning of large-span saddle-shaped cable net under the non-uniform force. It makes a breakthrough in the key technology of precast, installation and control precision measurement of extra-large special-shaped flexible structure roof, and realizes the transformation of precision engineering measurement from “static to dynamic” and “discrete to continuous”. A new model driven method for measuring the apparent morphology of a multi-purpose high-density netted tube is developed. It solves the problem of long distance continuous floor elevation measurement with ultra-high precision in blocked or closed environment. It effectively guides the construction operation and provided a guarantee for the development of the 2022 Winter Olympic Games speed skating project.

Using FME and VBA to extract the elevation data of airport grid

LI Chengpeng, YANG Yuanxin, ZHANG Yunming

2021, 0(8):  129-134.  doi:10.13474/j.cnki.11-2246.2021.0256

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The ground of the point cloud classification after get point cloud data currently in LAS cannot completely applied to design software for design calculation. Through the screening of the proposed technical scheme, the method of using the data processing function of FME Workbench combined with VBA programming to provide the plane data of external grid is proposed. In the FME Workbench, the ground point cloud data is used to construct TIN, the grid elevation data is extracted from TIN by point-by-point interpolation method, the contour line is generated, the corresponding graphic processing and the output of results are achieved, and the effectiveness of the method is demonstrated by the actual calculation examples.

Land use planning framework for China’s large river basins under the new ecological civilization development

WANG Yibo

2021, 0(8):  135-139.  doi:10.13474/j.cnki.11-2246.2021.0257

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Based on the analysis of the historical changes in the hydroecological environment management methods for China’s large river basins, this study investigates the new national demands for ecological civilization development, expands the current management framework by designing new water functional zones, adjusting the functional roles for basin units, and highlighting the integrity of the basin, which is to propose the new management framework based on the concept of country-basin-zone-unit-administrative division. The study also designs a set of metrics to measure the status of water ecology, water resources and water environment to clarify the ecoenvironment controling measures and policy implementation methodology in large river basins. The study could be a valuable policy reference for designing large-scale land planning strategy for land use planning in China’s large river basins under the new situation.

Data management of railway tunnel construction based on BIM and spatial big data technology

MIN Shiping, LIN Guoqing

2021, 0(8):  144-149,153.  doi:10.13474/j.cnki.11-2246.2021.0259

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Aiming at the problems of difficult storage of massive heterogeneous data, non-sharing of information, non-intuitive display and insufficient utilization of data value in railway tunnel construction projects, et al, in this paper, BIM and large spatial data technology are used to solve the problems of distributed storage, network sharing, three-dimensional query, intelligent analysis and decision-making of massive heterogeneous data in tunnel construction projects, and to achieve efficient information management of tunnel construction projects.In this paper, the technical scheme of dynamic establishment of BIM three-dimensional model of railway tunnel is proposed, the cloud platform framework of large spatial data for tunnel construction management is designed, and a set of cloud platform for large spatial data management application of railway tunnel construction is developed. Through the successful development and application of the platform, the feasibility of the framework system is verified, and the informationization level of tunnel construction project management is improved.

Construction and application of distribution cable mobile GIS system supported by GNSS

WANG Yanli, GAO Kaichao, LIU Baoqiang, ZHOU Congwei

2021, 0(8):  150-153.  doi:10.13474/j.cnki.11-2246.2021.0260

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In order to meet the requirements of information and intelligent management of distribution cables, this paper designs and develops a mobile GIS management system for distribution cables based on satellite navigation positioning, mobile internet, geographic information system and other technologies, which solves the technical problems such as fragmentation of cable channel elements, integrated storage of cable well profile data and spatial data, high-precision positioning of mobile devices, et al. The unified management of distribution cable data resources and the fast and accurate positioning of line paths have been achieved. The practical application shows that the mobile GIS management system developed in this paper provides technical support for the planning and design of distribution network, line finding, et al. It improves the efficiency of distribution network emergency repair, and promotes the informationization and scientific process of distribution network planning and design, operation and maintenance management.

Application of GEDO IMS system in the precision measurement of ballast railway

WANG Xiaoming

2021, 0(8):  154-157.  doi:10.13474/j.cnki.11-2246.2021.0261

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Due to the high precision and precision of the ballast railway precision measurement work efficiency, the conventional manual means of measurement accuracy is low, track geometric state measurement instrument measurement speed is slow, so they cannot meet the ramming progress of the ballast railway.This paper introduces the working principle of GEDO IMS system, focuses on the precision and precision of its application to the ballast railway, as well as the comprehensive testing of the combined large machine ramming operation.

Research on land subsidence using time-series InSAR technology in loess fill area

WANG Jianye, LIANG Xiaolong, JIN Xi, BAI Zechao, QI Erheng

2021, 0(8):  158-161.  doi:10.13474/j.cnki.11-2246.2021.0262

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Geotechnical engineering such as “cutting hills and filling ditches to build land” is not uncommon in collapsible loess gully areas. It is a great significance to known the subsidence of the fill area. 56 scenes of TerraSAR-X StripMap mode images were collected from November 2017 to December 2020. The time series InSAR technology is used to monitor the subsidence of a collapsible loess fill foundation project in northern Shaanxi. The subsidence measurement results of 3 benchmarking points are compared to verify the monitoring accuracy of the InSAR results. The results show that the surface of the fill area is dominated by subsidence, and the surface of the excavation area is dominated by uplift. There is a relatively obvious surface subsidence in the study area, which is located in the fill area near the fill-excavation boundary line. The subsidence rate range is -40~-20 mm/a. The maximum subsidence rate is -49.9 mm/a, and the cumulative subsidence is 151.6 mm. the time series InSAR subsidence results are in good agreement with the field leveling results. The error in the vertical subsidence rate is 1.8 mm/a, indicating InSAR technology has good application value in deformation monitoring of collapsible loess fill and excavation area.

The mehod of design and optimization of spatial search engine based on MongoDB

PAN Guofu

2021, 0(8):  162-165.  doi:10.13474/j.cnki.11-2246.2021.0263

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This paper introduces the spatial query capabilities of MongoDB, which is No-SQL database, and proposes an optimization strategy of the spatial query engine for application scenarios with large concurrent services of massive users. According to the characteristics of little change in content in a short time and high similarity of search results in adjacent locations, this strategy uses a gridstrategy to reduce the number of database operations under the premise of equivalent query results, and uses a memory buffer strategy to reduce disk I/O reading and writing times, thereby improving the concurrency and query speed of the service system. Tests results show that under the same hardware facilities, the optimized search engine efficiency is nearly 50 times higher than that of the original system.