Table of Content

25 May 2020, Volume 0 Issue 5

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Review of the development of global marine remote sensing satellite

WANG Wenjie, JIA Dongning, XU Jiali, CHU Hongkui, DONG Xiaorui

2020, 0(5):  1-6.  doi:10.13474/j.cnki.11-2246.2020.0134

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With the world attention of the marine resource growing, more and more countries are beginning to develop marine remote sensing satellite technology, providing services for marine monitoring, marine shipping, marine environment, marine military and marine economy. Through the statistical analysis of global marine remote sensing satellite information and its related parameters, it can help us to grasp the development trend of marine remote sensing satellites in the future. According to the analysis results, the marine remote sensing satellite is developing in the direction of multi-load, high-resolution and full coverage,and it poses new challenges to the launch conditions of the satellites and the loads they carry.As the types of loads increase and the transmission rate improves,the generated satellite data appears multi-source heterogeneity and the amount of data increases dramatically. So, only by establishing large satellite data centers and forming an integrated supporting system can we provide better services for all fields of the marine.

Application status and prospect on water resources investigation and monitoring by satellite remote sensing

JIN Jianwen, LI Guoyuan, SUN Wei, YANG Xiongdan, CHANG Xiaotao, LIU Ke, LIU Yao

2020, 0(5):  7-10.  doi:10.13474/j.cnki.11-2246.2020.0135

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Aiming at the limitations of traditional water resources survey and monitoring methods, such as low efficiency, high cost and difficulty, it is of great significance to carry out survey and monitoring of water resources based on satellite remote sensing.Meantime, it plays an important role in maintaining the red line of water resources utilization, guarding green mountains and clear water and building ecological civilization.This paper combs relevant research results and introduces the specific content of satellite remote sensing in water resources investigation and monitoring, and focuses on the application status of satellite remote sensing in water location, area, water level, water storage, runoff, water quality, etc. Finally, the existing problems in the current application are analyzed and the future work is prospected.

Research and application of virtual geographic environment in smart city

ZHANG Xinwen, ZHANG Chunxiao

2020, 0(5):  11-15,30.  doi:10.13474/j.cnki.11-2246.2020.0136

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Smart city is the updated version of digital city. The dynamic implementation of its management services is closely related to the virtual geographical environment. Firstly, the overview of virtual geographic environment is summarized. Then, the key technologies of the virtual geographic environment in smart city is concluded, and 3D dynamic simulation, actual interaction, multi-agent, and the characters digital twin and scope of their application are analyzed. Then the research status and challenges of virtual geographical environment in smart city are analyzed from the perspective of application. Finally, the prospects in the new era of artificial intelligence and VR of the virtual geographic environment in the real-time display, efficient algorithm and actual interaction are concluded.

Remote sensing image change detection algorithm based on random forest

LIU Xia, GUO Yanan

2020, 0(5):  16-20.  doi:10.13474/j.cnki.11-2246.2020.0137

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Random forest is an emerging and highly flexible machine learning algorithm with good stability in prediction and classification, and the performance of the algorithm is better than many single predictors. In view of this, a remote forest image change detection algorithm for random forests is proposed. The entropy rate method is used to superpixel segmentation of remote sensing images to obtain optimal segmentation results. A remote forest image change detection model based on random forest is constructed. The extracted Gabor features and spectral features are used as model inputs for training and prediction, and the decision tree voting is used as the final change detection result. The experimental results show that the random forest change detection model constructed in this paper is significantly lower than other algorithms in the missed detection rate and false detection rate, and the overall correct rate is the highest, and the algorithm time is also significantly better than other algorithms.

Geometric misalignment repair and seamless stitching in DOM

ZHANG Chunsen, REN Li, GUO Bingxuan, REN Qisheng

2020, 0(5):  21-24.  doi:10.13474/j.cnki.11-2246.2020.0138

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Aiming at the geometric misalignment and image mosaic problems in the production of digital orthophoto (DOM), combined with the occlusion detection method and the image registration method based on the TPS thin-plate spline model, the geometric misalignment of the image is repaired and seamlessly spliced. The repair of the geometrically misaligned area is divided into the inner side and the outer side according to the acquired three-dimensional characteristic line. The inner side is repaired by orthorectification. The outer side is selected as an unobstructed image for image registration and then filled. The algorithm is verified by the real over-the-horizon geometric misalignment image. The results show that the method used in this paper can effectively avoid the “bilateral” phenomenon caused by the occlusion image while repairing the geometrical misalignment of the viaduct area, and guarantee the local orthomorphic after the repair. Seamless stitching of images and original orthophotos.

Implementation and accuracy evaluation of ICESat-2 ATL08 denoising algorithms

CAO Bincai, FANG Yong, JIANG Zhenzhi, GAO Li, HU Haiyan

2020, 0(5):  25-30.  doi:10.13474/j.cnki.11-2246.2020.0139

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According to the characteristics of photon counting laser point cloud, this paper studies and implements the point cloud denoising algorithm in ICESat-2 ATL08 technical document and carries out the accuracy evaluation. Firstly, the total number of points in the neighborhood of the target point is calculated point by point as the local density value. Since the signal is usually more concentrated than the noise in the spatial distribution, the density histogram often exhibits the double peak characteristic of noise on the left and the signal on the right. Then, initial parameters of noise and signal Gaussian function are calculated by peak calculation and distance judgment, and Gaussian fit and expectation-maximization algorithm are adopted for fitting two exact waveform position. Finally, the intersection position of the double Gaussian function is taken as the denoising threshold. The points smaller than the threshold are marked as noise, and the points greater than the threshold are signals. The experimental results of MABEL data show that when the data exhibits typical bimodal distribution characteristics, the algorithm has excellent denoising effect, and the accuracy is better than 98%. When the data does not meet the bimodal characteristics, the effect becomes worse.

Feature extraction of building point clouds based on Morse theory

LI Hongmei, ZHANG Chunkang, ZHANG Xia, LUO Zhu

2020, 0(5):  31-35,42.  doi:10.13474/j.cnki.11-2246.2020.0140

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Aiming at the problems of traditional feature extraction algorithms, such as cross disorder, discontinuity and lack of topological relationship, this paper proposes a point cloud feature extraction algorithm based on Morse theory. Firstly,the Morse function index of the vertices on the 3D surface model is defined. Secondly, the adjacent point comparison method is used to extract the feature points automatically. Finally, aiming at the problem that the duality of Morse-Smale complex has no practical significance in building topology features, a single complex topology model extraction and simplification algorithm is proposed. The experimental results show that the algorithm can obtain clear, continuous and complete building feature lines and realize the complete segmentation of the building model surface. On the premise of ensuring the topological consistency of building feature lines, the simplified algorithm can obtain different levels of building topology features, which provides a guarantee for the reconstruction and visualization of building models.

Remote sensing image semantic segmentation supported by deep convolutional neural networks

XIE Meng, LIU Wei, LI Erzhu, YANG Mengyuan, WANG Xiaotan

2020, 0(5):  36-42.  doi:10.13474/j.cnki.11-2246.2020.0141

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Aiming at the problem of category imbalance and insufficient utilization of context information in high-score remote sensing image semantic segmentation, this paper proposes an optimized DeeplabV3 + algorithm. Firstly, the data imbalance problem is solved by modifying the cross-entropy loss function. Secondly, it replace the ASPP module with Vortex Pooling to improve the context information. Then it use multi-scale input to make full use of the multi-scale information of the image. And then it use the voting strategy for feature fusion to improve the accuracy of image segmentation. Finally, morphology is used for post-processing to eliminate stitching marks and noise. Train on the CCF contest dataset and compare it with other classic semantic segmentation algorithms. The experimental results show that the algorithm in this paper makes full use of contextual information, effectively reduces misclassification, makes segmentation boundaries more accurate, and captures linear targets more effectively. The MIoU on the entire test image can reach 85.21%, which is significantly better than the SegNet and U-Net algorithms.

Wavelet coefficients segmentation for locally adaptive threshold image denoising method

LI Yali, ZHANG Songlin, HAN Jie

2020, 0(5):  43-46,122.  doi:10.13474/j.cnki.11-2246.2020.0142

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Aiming at the problem that the square local window of the adaptive wavelet threshold denoising can not well adapt to the edge features of the wavelet coefficients, a new image segmentation-based method is proposed. In this method, multi-scale wavelet decomposition is firstly performed on the noisy image. Then, the different scale wavelet coefficients are segmented by using the SLIC superpixel segmentation technology with which some local blocks with similar statistical characteristics will be obtained. BayesShrink thresholds of the wavelet coefficients in every irregular block are estimated and soft threshold shrinkage is utilized. Finally, a denoised image is acquired by the inverse wavelet transform. In this paper, three standard test images and a hyperspectral image are tested. The experimental results show that the proposed method can better adapt to the edge features of the wavelet coefficients, and can not only get better visual effects, but also achieve a higher level of numerical indicators.

Planar point cloud denoising using the methodology of fusion of principal component analysis and local neighborhood

CHEN Jianhua

2020, 0(5):  47-50,68.  doi:10.13474/j.cnki.11-2246.2020.0143

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Large hydraulic structures are very important infrastructures of the nation. It has become a research hotspot to realize the deformation monitoring using laser scanning technique. Buildings are with many planar structure characteristics, and in order to remove the noise efficiently from the point cloud of planar structures, the methodology combining principal component analysis and local neighborhood is proposed. Firstly, the global noise is eliminated using principal component analysis, and the local noise is detected and removed by considering its local neighborhood. The methodology is verified by the measured data and the results demonstrate that the proposed methodology has the advantages of high-efficiency and feasibility, which is of high application value.

Local structure based line segment matching for wide-baseline images

YAN Shaohua, CHEN Min, ZHAO Yitao, TAN Guihong, ZHAO Xi

2020, 0(5):  51-54.  doi:10.13474/j.cnki.11-2246.2020.0144

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Aiming at the problem that the variation of wide haseline image view makes it difficult to obtain the raliable matching results by the exisiting linear feature matching methods. A local structure constraint based robust line segment matching method is proposed in this paper for wide-baseline images with viewpoint change. Firstly, extract the line segment in images and grouped according to the rules. Secondly, viewpoint invariant feature region is constructed based on the geometric relationship between line segments, a feature descriptor is computed for each feature region and initial matches are generated by measuring feature descriptor similarity. Then, an outlier elimination method is designed by exploring the relationship of feature region vertices coordinates of the initial matches. Finally, a line segment matching expansion step is proposed to improve matching performance. The experimental results demonstrate that the proposed method performs better than traditional methods for wide-baseline images with large viewpoint change in terms of a large number of correct matches and matching precision.

Color point cloud classification of mine surface

CAI Lailiang, SONG Deyun, WEI Fengyuan, XUE Yuan, SHU Qianjin

2020, 0(5):  55-58.  doi:10.13474/j.cnki.11-2246.2020.0145

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Taking the color 3D laser point cloud data of the mining area as the research object, a fast automatic classification and target extraction method for the point cloud of the mining area is proposed. Firstly, the H value in HSV space is calculated according to the RGB value of color point cloud. According to the difference of H value among different objects, the points of ground point and non ground point are extracted according to the prior value of ground object color. Then, the extracted points are clustered and calculated. Using the significant difference in spatial distribution of all kinds of ground object point clouds, layered cross-section projection is adopted, and the ratio of length to width of the minimum bounding box of projection points is used In this paper. Finally the RIEGL vz-1000 scanner is used as the experimental object to verify the feasibility and practicability of this algorithm.

Deformation field extraction and simulation of Changning earthquake based on D-InSAR

YU Xiangwei, XUE Dongjian, WANG Haifang

2020, 0(5):  59-63.  doi:10.13474/j.cnki.11-2246.2020.0146

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On June 19, 2019, the Ms6.0 earthquake occurred in Changning County, Sichuan Province. The seismic coseismic deformation field was extracted and the focal mechanism was inverted. It is of great significance for the analysis of earthquake rupture and guiding disaster relief. Two-track differential interference processing is used to cover the two scenes of Sentinel-1A image in the area affected by Changning earthquake. Based on the research on key technologies and image features of D-InSAR, the processing methods and parameters are configured to extract the coseismic deformation field of the earthquake. The Okada model and forward modeling are used to invert and simulate the geometric parameters and deformation fields of the seismogenic fault. The results show that the deformation field of Changning earthquake is irregular elliptical shape controlled by the northwest-oriented secondary fault. The characteristics of the two sides of the fault are obviously different. The lower left side of the fault is the subsidence area, and the upper right side is the uplift area. The maximum line of sight of the two is the maximum line of sight. The deformation is 8 and 6 cm, respectively. The motion of the fault is mainly left-lateral strike-slip, the average sliding distance is about 0.38 m, and the average sliding angle is about 55°. The positive simulated deformation field is consistent with the observation results, which proves that the observation results are more reliable and improve the observation accuracy of the low coherence deformation zone.

Design and implementation of laser SLAM accuracy test field

YANG Xiaotian, LI Guangyun, XIANG Fengzhuo, WANG Li, LUO Haolong

2020, 0(5):  64-68.  doi:10.13474/j.cnki.11-2246.2020.0147

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SLAM systems have been widely used in the fields of robotics, autonomous driving, and mobile measurement, but the current system accuracy test methods are not perfect. Aiming at the actual needs of SLAM system accuracy testing, a method for establishing a SLAM high-precision test field is proposed. Firstly a three-dimensional control network is established. Then three-dimensional laser scanning technology is used to collect environmental information. Finally a high-quality 3D point cloud feature library for SLAM system accuracy test is constructed. The experimental results show that the established 3D point cloud feature library contains rich feature information, has real geographic coordinates, and has an accuracy of mm level, which can better meet the needs of SLAM accuracy testing.

Estimate of BDS satellite real-time clock offset

RAO Pengwen, MAO Ya

2020, 0(5):  69-72,100.  doi:10.13474/j.cnki.11-2246.2020.0148

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With the rapid development of high-tech such as unmanned driving, real-time precise single point positioning has attracted more and more attention in the field of GNSS. It is of great practical significance to study the acquisition of real-time satellite clock error and the accuracy of real-time positioning. In order to study the influence of coupling BDS satellite orbit and clock error products on positioning accuracy, different precision orbit products are used to acquire satellite clock error in real-time. It studies the correlation between satellite clock offset and orbit error as well as the ability of satellite clock offset to absorb orbit error. The results show that the satellite clock offset can absorb 95% of the orbital error in radial and partial tangential error, and some extent compensate for the positioning error caused by the orbital error. Using coupled satellite orbit and clock difference products, the positioning accuracy of a single BDS system can reach decimeter-level positioning results.

A method for travel safety analysis supported by user GPS trajectory data

ZHANG Yong, ZHU Daming, FENG Yu, DAI Decheng

2020, 0(5):  73-79.  doi:10.13474/j.cnki.11-2246.2020.0149

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Security is one of the important factors in every trip, traditional methods are mostly based on human or video collaboration to complete security monitoring, and there is no way to measure travel by trajectory data. With the technological improvement of positioning and tracking systems, the continuous development and popularization of GPS satellite positioning technology makes it possible to collect and use GPS data points on car navigation devices and handheld GPS devices.This paper proposes a method for evaluating security based on user GPS trajectory data, and uses trajectory data between dormitory and laboratory in the campus as the research object to verify the effectiveness of the method. Research shows that the user trajectory off the safety trajectory obtains a lower safety score. Conversely, if the user trajectory is very similar to the safety trajectory, a high safety score is obtained. This method is very efficient in verifying whether the user trajectory is similar to the safety trajectory or not, and at the same time, the form of the trajectory data reflects the user’s travel safety.

Application of mean shift model in anomalous station detection of crustal deformation analysis

FAN Chengcheng, ZHANG Jun, LEI Qiankun, WU Yu, HUANG Kangyu

2020, 0(5):  80-84.  doi:10.13474/j.cnki.11-2246.2020.0150

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In the analysis of crustal movement and deformation, it is generally believed that mass movement is featured by rigid motion, and the status of the block is considered as remarkably stable. However, due to local tectonic movement of the block and the gross error, abnormal movement will be observed from a few survey station. Only by removing these abnormal stations can the reasonable analysis results of the long-term movement trend and motion law of the crust in the study area be obtained. For a long time, the most common way to screen station is to see if the difference value between the posterior estimate of the residual standard deviation and residual error is beyond some limiting value. This method fails to eliminate abnormal stations efficiently. This paper proposes to use the mean shift model to eliminate the anomaly stations, and compare it with the quasi calibration method and the traditional residual-standard-deviation-based simple LS estimation method. The fitting analysis result of the recent velocity field data of GPS observation of China’s tectonic environment monitoring network in the Circum-Bohai-sea area shows that the iterative processusing the mean drift amount can not only screen the stations robustly, but also avoid the impact raised by selection inaccuracy of Quasi-Accurate-Observationand is able to obtain a higher velocity field fitting accuracy compared with the quasi-calibration method.

Application of local mean decomposition and singular value decomposition in noise reduction of GNSS station coordinate time series signal

QIU Xiaomeng, WANG Fengwei, ZHOU Shijian, ZOU Shilin

2020, 0(5):  85-89.  doi:10.13474/j.cnki.11-2246.2020.0151

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In order to effectively extract useful information from coordinate time series of GNSS station, and reduce noise interference, this paper proposes a signal denoising method that combining local mean decomposition with singular value decomposition. Experiments were carried out using measured coordinate time series of five stations. Firstly, the coordinate time series is decomposed into a series of PF components and residuals by local mean decomposition, and then the continuous mean square error method is used to determine the boundary between the high frequency component and the low frequency component. Keep the low-frequency components unchanged, and use the singular value decomposition method to denoise and reconstruct the high-frequency components. Finally, the reconstructed high-frequency components and low-frequency components are superimposed to obtain the final de-noising coordinate time series, and the noise reduction effect is compared and analyzed. The results show that compared with the simple singular value decomposition, the local mean decomposition combined with singular value decomposition can adaptively select the appropriate number of singular values for signal reconstruction, which improves the noise reduction effect.

Analysis of influence of emergency environment anchor deployment on positioning accuracy

YANG Deng, WANG Jian, WANG Minmin, ZHANG Yalei

2020, 0(5):  90-94.  doi:10.13474/j.cnki.11-2246.2020.0152

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In the disaster environment, this paper research the UWB positioning accuracy about the relative location between UWB anchor and tag, different antenna direction, different height of anchor deployment, different number of anchor and different deployment network types. The experimental results show that: the height of the anchor has no obvious influence on the two-dimensional positioning accuracy of UWB; the closer the tag is to the anchors’ network center, the higher the positioning accuracy; higher positioning accuracy when the antenna is oriented vertically; the greater the number of anchors, the higher the positioning accuracy; rectangular mesh type has higher accuracy in common mesh types. Therefore, the UWB anchor can be set up, in the emergency environment, according to the plan of “the positioning area as a center, the antenna is vertical, the number of anchors is as large as possible, and the rectangular network type”. The sub-optimal positioning accuracy will be got in the shortest time and the guidance for feasible anchor deployment for UWB emergency positioning will be obtained.

Building facade window model construction of vehicle point cloud data

FAN Huilong, LI Yongqiang, YANG Qingke, LI Pengpeng, LIU Yakun, ZHAO Shangbin

2020, 0(5):  95-100.  doi:10.13474/j.cnki.11-2246.2020.0153

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Using vehicle LiDAR data to build window model is a hard work. First, the RANSAC algorithm is used to detect and separate the main wall of the building facade, and the Windows on the main wall are clustered based on empty ideas. Then, the dynamic elliptic convex hull algorithm is used to detect the boundary contour points of windows. The obtained window boundary points are segmented by RANSAC algorithm, and the linear fitting and corner point restoration are carried out by using the robust global least squares algorithm. Finally, the window model construction is completed by combining the geometric features of the Windows. The experimental results show that this method can accurately and effectively construct window models in building facades.

Urban fire hazard assessment based on multi-source spatiotemporal data

ZHAO Xiaoxu

2020, 0(5):  101-106.  doi:10.13474/j.cnki.11-2246.2020.0154

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The fire risk assessment at the city level mainly includes fire hazard, fire harmfulness, and fire emergency response capability. This article selects fire hazard assessment for targeted research. In the era of big data, causal relationships could be replaced with correlation. Thus, multi-source data is used for weighing and scoring the evaluation indicators in order to obtain a spatiotemporal distribution of fire danger in the urban area of Fuzhou. First, address analysis of the fire alarm records in the past few years is performed using the AMap API tool, and nearly 10 000 fire alarm locations are spatially assigned mapping the spatial distribution of historical fires in Fuzhou. Furthermore, multi-source and heterogeneous data, such as the structure of urban land use, property of land use development, and thermal map of population distribution, is further integrated to explore its correlation with the spatial distribution of historical fires. Finally, taking Fuzhou as an example, the results of dynamic fire risk assessment are formed, and the fire risk assessment method with sufficient mathematical support is developed, which provides strong support for urban fire control planning.

Application of superpixels in multipolar SAR data classification: taking ALOS PALSAR as an example

LIANG Xueping, XUE Dongjian, JIA Shichao

2020, 0(5):  107-110.  doi:10.13474/j.cnki.11-2246.2020.0155

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In view of the proposed polarization synthetic aperture radar data classification method is difficult to obtain both the boundary and adjacent information of the ground, and in order to reduce the consumption time of image processing, a super-pixel generation algorithm-inear iterative clustering method is introduced, and the geoclassification of the advanced earth observation satellite SAR multipolar data in Japan is studied. Based on the border area of Pengzhou and Shifang city in Sichuan Province, the paper uses Pauli decomposition to generate RGB false color images and filter them, and then uses linear iterative clustering method to generate superpixels on this basis, and finally uses the support vector machine classification method to select polarization entropy reasonably, The polarization features such as anisotropy and average scattering angle are combined as classification parameters to compare and analyze the classification results of pixel-based and hyper-pixel-based polarization SAR images. Experiments show that the use of superpixels is better than other pixel-based classification methods, the overall accuracy of superpixel classification is 95.23% and the Kappa coefficient is 92.58%.

Method of handling suspended ground objects in tilt photography real scene model

WANG Zheqi, XU Liuhua, YU Zhiqiang

2020, 0(5):  111-114.  doi:10.13474/j.cnki.11-2246.2020.0156

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In order to better solve the excessive dependence of the traditional tilting photography real scene model on the three-dimensional editing environment, a real scene model suspended ground object processing technology based on oblique photography triangle network analysis is proposed. The technical method reduces the dimensionality of the three-dimensional triangular network, analyzes the radiation characteristics of the edge on the two-dimensional triangular network node after dimension reduction, and quickly locates the edge point of the feature, and combines the cluster analysis algorithm and the minimum convex edge extraction technology. The rapid positioning and elimination of the boundary of suspended objects is realized. The suspended objects such as vegetation are selected as the research object. It is verified that the technical method has good applicability to dealing with the suspended photographic real scence model, and can greatly reduce the requirements of the three-dimensional environment and the data processing difficulty in the processing of the oblique photography real-world model.

Analysis of virtual grid technology impact on dynamic positioning of network RTK

LI Lihong, SHI Junbo, OUYANG Chenhao

2020, 0(5):  115-118.  doi:10.13474/j.cnki.11-2246.2020.0157

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For the consideration of RTK users of large concurrent networks, the virtual grid technology has been gradually generalized in the upgrade of BeiDou ground-based augmentation system. This paper first introduces the principle of virtual grid technology, and takes the Qianxun BDS ground-based augmentation system as an example to study the implementation procedures and details of virtual grid technology. Meanwhile, the rule of the Qianxun BDS ground-based augmentation system virtual grids’ distribution in April 2018 and June 2019 is analyzed in this paper. Then, for the dynamic positioning application, the influence of virtual grid point switching on dynamic positioning is studied. The results show that the effect of virtual grid point switching on dynamic positioning is in the centimeter level, which can be neglected for vehicle dynamic applications. This paper has reference significance for the large concurrency and dynamic application of BDS ground-based augmentation system in the future.

Deformation monitoring of Wanshou temple tower based on 3D laser scanning

YANG Yonglin, YANG Chao, PAN Dongfeng, ZHU Haixiong, MA Tao, ZHAO Yanjun, WANG Shuangyu

2020, 0(5):  119-122.  doi:10.13474/j.cnki.11-2246.2020.0158

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Aiming at the problem that adopting traditional measurement approaches to monitor the deformation with respect to ancient tower site is with complex process and low precision, this paper use 3D laser scanning method to perform the deformation monitoring while propose a slope calculation algorithm based on least squares principle. The method tirstly extracts the contour point cloud of each layer with respect to the tower first, then fits the center of each layer according to the principle of least squares, conducting linear fitting to extract the central axis of the tower, and finally calculates the tilt amount of the tower. Taking the deformation monitoring of Wanshou temple tower in Xi’an as an example, the experimental results show that the proposed algorithm can quickly calculate the inclination of the tower and improve the working efficiency in contrast to the traditional monitoring methods.

Application of revit on house property survey and mapping

QIU Feng

2020, 0(5):  123-126.  doi:10.13474/j.cnki.11-2246.2020.0159

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With the development of surveying and mapping theory and new technologies and instruments, house property surveying technology is also constantly evolving.In recent years, owing to the great support of the national policy,these have brought great innovation and advancement to the traditional informatization mapping.The Autodesk company is offering BIM solutions under the banner of Revit,which can be widely found in building design. However, it is still shortage of the study on measuring the area on drawings quickly in the market.This paper makes detailed discussion on house property surveying by Revit and gives a practical instance about exporting walls median-line.

Application of combination model of quadric surfaces and least squares collocation in GPS height anomaly fitting

Lü Jianwei, ZHANG Zhihua, ZHANG Xinxiu, LIU Zuyu

2020, 0(5):  127-129,133.  doi:10.13474/j.cnki.11-2246.2020.0160

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In engineering practice, in order to make the best of GPS elevation data and reduce the dependence on traditional leveling, it is very important to improve the fitting accuracy of GPS height anomaly. Therefore, based on the analysis of the basic principle of quadric surfaces fitting and least squares collocation fitting and the derivation of algorithm process, a new height anomaly fitting method is proposed. According to quadric surfaces fitting, the residual value sequence between the original observation data and the fitting data is calculated, and then the comprehensive error including the quadric surfaces fitting model error is optimized and weakened by using the least squares collocation model. Finally, a new height anomaly is obtained. Through an example, the quadric surfaces fitting method and the least squares collocation method are compared with the new method separetely proposed in this paper. The results show that the fitting prediction accuracy of the new combination method is obviously better than that of the least squares collocation and quadric surfaces fitting.

Method of automatic production for maps of deformed traffic routes

CAI Xianhua, WANG Lang, FU Xiao

2020, 0(5):  130-133.  doi:10.13474/j.cnki.11-2246.2020.0161

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The traffic route maps have become common for the expansion of urban transportation networks. In order to improve the information transmission efficiency and better ensure the clarity and legibility of the graphics, deformed traffic route map has been proposed. In this paper, characteristics of deformed traffic route maps are analyzed and the automatic production processes are summarized. To solve conflicts of map symbols in the production process, a method of compression and deforming for traffic route map is come up with based on station displacement, which is driven by force. A displacement model of forced station in traffic route maps is constructed and a displacement algorithm centered on coordinate axis is designed. It shows in the experiment that the conflicts of map symbols can be settled using this algorithm, which establishes the basis for completely automatic production of deformed traffic maps.

Detection and repair of reference station cycle slip using differential observations among epochs

WANG Li, FAN Yongzhao

2020, 0(5):  134-137,141.  doi:10.13474/j.cnki.11-2246.2020.0162

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Carrier phase observables is the basis of high-precision satellite navigation and positioning and its related applications. The correct resolution of the integer ambiguity is the key to achieve centimeter-level navigation, positioning and nano-level timing. Cycle slip detection and repair will directly affect the performance of integer ambiguity resolution, especially for the core infrastructure of high-precision location service such as CORS (continuous operation of reference station) networks. Ensuring continuous and reliable ambiguity resolution is important to achieve high-precision location service. The reference station receiver has the characteristics of high accuracy, static, and a high sampling frequency (generally 1 Hz), et al. In a short time interval, the errors of ionospheric delay, tropospheric delay, and hardware delay have a strong correlation. Based on the above characteristics, this paper applies the inter-epoch difference method to the reference station cycle slip detection and repair. Refer to the characteristics of the reference station stationary, a cycle slip detection and repair method suitable for the reference station is proposed. This method does not require multi-frequency combination of observations while avoids the influence of pseudorange noise. It has high detection accuracy, and can detect each frequency of a single station separately. In the process of cycle slip repair, It considers the non-integer gross error and removes it. Experiments show that this method can accurately detect and repair the whole week cycle slip of 1 week, and can detect the non-integer gross error with decimal deviation more than 0.1 week.

Product pattern design and key technology of image topographic map

YANG Huishan, LIN Chao, LEI Lizhen, DAI Jiangou

2020, 0(5):  138-141.  doi:10.13474/j.cnki.11-2246.2020.0163

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Using the case for 1:10 000 image topographic map in Guangdong Province, on the basis of investigation, analysis and production test, this paper designs one product pattern of image topographic map, discusses the key technologies such as contours generation, elevation point extraction, vector element selection, annotation,symbolization,and map border decoration.The corresponding production process and technical method are developed, and the product samples are made. These research results have formed a series of technical documents, which can provide reference for the design and scale production of image topographic map.

Development of ability to solve complex engineering problems for engineering college students

XU Xianze, XU Fengqiu

2020, 0(5):  142-145.  doi:10.13474/j.cnki.11-2246.2020.0164

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The development and innovation of surveying and mapping instrumentation is not only an important part in the training of undergraduate engineering talents in the current surveying and mapping informatization phase, but also the basic requirement for solving “complex engineering problems” in the certification of standard engineering education. The comprehensive design training of instrumentation system effectively develops the ability of solving “complex engineering problems” for the engineering college students. With the connotation of “complex engineering problems” in professional certification clarified in this paper, the design method of comprehensive training experiment content for instrumentation system is introduced, the relationship between design tasks and “complex engineering problems” is organized, and the practical curriculum content is optimized based on the class feedback. In this case, the trains for the capacity of solving “complex engineering problems” are realized in practice, which provides the benchmark to formulate the training program for major of surveying and mapping, instrumentation, et al. and meets the requirements of certification standards in engineering education.

Curriculum reform and practice of education in the course of surveying

WANG Haoyu, REN Chao, LIU Lilong, LIANG Yueji, LU Xianjian, DOU Shiqing, GAO Ertao

2020, 0(5):  146-149.  doi:10.13474/j.cnki.11-2246.2020.0165

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The core issue of education reform is the reform of the curriculum. Only when education reform enters the classroom level is the deep water area that has truly entered the education reform. Based on the curriculum reform of surveying, this paper summarizes the continuous construction of the surveying curriculum reform, and proposes and continuously enriches the teaching philosophy of “One Center, Three Education People”. Deepen the reform of teaching resources and construct a long-term “multi-subject, whole process, quantifiable” curriculum development mechanism. Teaching and learning, and the realization of the surveying course teaching “heavy quality, strong ability, multiple openness”.

Construction quality control and disease detection of subway tunnel based on 3D laser scanning technology

SONG Yunji, WANG Zhi

2020, 0(5):  150-154.  doi:10.13474/j.cnki.11-2246.2020.0166

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The 3D laser scanning technology has the characteristics of no contact, high density, high precision and digitization, and can realize the holographic, comprehensive and rapid 3D measurement of subway tunnel. In the civil construction stage, the three-dimensional scanning of the first branch and the second lining of the tunnel can be carried out separately, and the over-underdigging and the second lining limit of the first branch section can be quickly obtained. In the operation stage of the subway tunnel, the mobile three-dimensional laser scanning technology is used to scan the tunnel, which can quickly obtain the holographic data of the tunnel, and can analyze and extract the disease information such as tunnel seepage, crack, pipe piece wrong platform and so on from the point cloud. The 3D laser scanning technology is used to test and apply the construction quality and disease detection of Qingdao subway parts, and its data acquisition process and point cloud analysis are introduced, which provides some reference for the popularization and application of 3D laser scanning technology in subway tunnel.

Application of mobile 3D laser scanning technology in deformation monitoring of subway tunnels

LU Peiqing, TANG Chao

2020, 0(5):  155-157,160.  doi:10.13474/j.cnki.11-2246.2020.0167

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The deformation monitoring of the tunnel structure during the operation phase of the subway ensures the safety of the subway operation. At present, the monitoring of subway tunnels in China mainly uses traditional total station instruments and other equipment for manual measurement. The deformation monitoring points laid by this method are limited, and the monitoring process is slow, which is difficult to reflect completely the overall deformation characteristics of the tunnel structure. In this paper, mobile 3D laser technology is introduced into subway tunnel monitoring. The implementation of the scanning method is used to quickly obtain the complete structural information of the tunnel. The automated post-processing software is used to comprehensively monitor the deformation information of the tunnel structure. Experiments show that the method can achieve rapid, comprehensive and reliable structural monitoring results of metro tunnels under the condition of meeting the monitoring accuracy requirements.

Application of Trimble image scanner SX10 in air raid shelter

LIU Pingli, WANG Chuanxian, ZHANG Hongxiang, LIU Songyuan, QIAO Tianrong

2020, 0(5):  158-160.  doi:10.13474/j.cnki.11-2246.2020.0168

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7401 air defense tunnel was built in Zhengzhou in 1960s and 1970s. It is mainly used to prevent war air strikes. Due to its disrepair, some of the air defense tunnels have collapsed, and there is water seepage in rainy season. Based on the detailed investigation of 7401 air defense tunnel, the position, spatial dimension, slope and damaged area of 7401 air defense tunnel are accurately measured by Trimble SX10 3D scanning system. It provides data basis for 7401 air defense tunnel repair.

A new fusion piling model based GPS,tiltmeter and rangefinder

WEI Changsuan, PENG Zhenzhong, LI Jun

2020, 0(5):  161-164.  doi:10.13474/j.cnki.11-2246.2020.0169

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The traditional piling model applied in projects of building coastal bridges requires the combination of two GPS systems, two tiltmeters or two rangefinders for positioning, which will fail if any device breaks down. This paper proposes a new fusion piling model that combines three GPS systems, two tiltmeters and two rangefinders. When one device breaks down, the problem will be monitored through an intelligent system, and a best choice will be made about the remaining devices to continue positioning. The new model can greatly improve the work efficiency.