Table of Content

25 March 2019, Volume 0 Issue 3

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GPS coordinates transformation based on convolutional neural network

CUI Fang, ZHAO Shuxu

2019, 0(3):  1-5.  doi:10.13474/j.cnki.11-2246.2019.0067

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The GPS coordinate conversion method is crucial for GPS space location system.In the past,many methods have been proposed to convert GPS coordinates,but the effect is not very significant.The reason is that most of the models have model errors and projection errors.In view of the shortcomings of the current methods,this paper proposes a GPS coordinate transformation based on convolution neural network (CNN) by using the advantages of deep learning on unstructured data processing method.This method transforms GPS data into unstructured image data and uses these unstructured image data as the input layer of CNN to train the GPS coordinate transformation model so as to minimize the requirement of data preprocessing and to learn from the data without supervision out of effective features.Experimental results show that this method has higher conversion accuracy than the traditional coordinate transformation method.

Position domain dual-frequency carrier smoothed code filter with colored noise

LUO Fei, CHANG Guobin, CHEN Chao

2019, 0(3):  6-10,60.  doi:10.13474/j.cnki.11-2246.2019.0068

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Carrier smoothing code algorithm is an effective data processing technology in global navigation satellite system,which has been widely used in many high-precision real-time applications.In the traditional algorithms,the colored noise of the time-differenced carrier phase is neglected.In order to resolve this issue,a range domain and position domain dual-frequency carrier smoothed code algorithm under the condition of colored noise with the finite impulse response in the recursive least-squares theory framework are proposed.Firstly,the conventional dual-frequency carrier smoothed code algorithm is introduced.Based on this,the algorithms of range domain and position domain carrier smoothed code in the recursive least-squares theory as well as the influence of colored noise are given.A real GPS experiment was made to test the validity of new algorithm.Experiment results indicate the carrier smooth code algorithm is able to improve the precision of pseudo-range observations.Compared with the conventional algorithm,both the smoothing accuracy of range domain filtering and position domain filtering are improved,the accuracy of 3-dimensional positioning error is improved.At the same time,it shows that the colored noise of the time-differenced carrier phase has a certain influence on the smoothing accuracy.

Characteristic analysis and correction of BeiDou satellite-induced code bias

ZHU Shaolin, YUE Dongjie, CHEN Jian, TANG Tongxu, ZHANG Yuan

2019, 0(3):  11-15,26.  doi:10.13474/j.cnki.11-2246.2019.0069

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There are systematic errors on BeiDou code pseudorange measurements because of the influence of satellite-induced errors which are called satellite-induced biases.The IGSO and MEO satellites can establish the correction model by the relationship between code bias and elevation,but the GEO satellite is difficult to establish the correction model because of the small change of elevation.In this contribution,with the analysis of characteristics of GEO satellite-inducedcode bias,a method of correcting is proposed based on singular spectrum ananlysis (SSA),and the correction effect is verified by the experiment of single point positioning (SPP) of ionosphere-free combination.The results show that after correction,the accuracy of GEO MP observation improves 39.9%,17.9% and 29.4% respectively in N,E and U,and the MW observation improves 41.3%.Correcting IGSO and MEO code bias with the traditional correction model has little influence on SPP,while correcting GEO and IGSO pseudo range errors with the singular spectrum analysis method improves the accuracy of SPP by 11.1% and 21.1% respectively in the plane and elevation direction.

An improved ORB-SLAM algorithm for feature extraction

ZHANG Liangqiao, CHEN Guoliang, XU Xiaodong, LIAN Dajun, WANG Rui

2019, 0(3):  16-20.  doi:10.13474/j.cnki.11-2246.2019.0070

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Aiming at the problem of poor real-time performance and trajectory drift in visual SLAM positioning in complex indoor environments,this paper proposes an ORB-SLAM algorithm based on image feature detection extraction method.The algorithm improves the efficiency and accuracy of image feature detection and matching in the front-end,introduces a closed-loop detection strategy to optimize camera pose trajectory,and improves positioning accuracy.The SIFT,SURF and ORB of different feature extraction algorithms are compared and analyzed in different sources.The robot motion trajectory is estimated by this algorithm.The relative pose error from the real trajectory is 0.144 8 m.Experiments show that the proposed method is feasible and robustness.

Method for SNPP-VⅡRS nighttime lights images denoising

ZHONG Liang, LIU Xiaosheng, YANG Peng

2019, 0(3):  21-26.  doi:10.13474/j.cnki.11-2246.2019.0071

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The high precision nighttime lights data can effectively reflect the characteristics of human space activities.The traditional SNPP-VⅡRS nighttime lights images denoising method is easy to ignore the newly added or disappeared effective light,and has not dealt with the light outliers.With the passage of time,the denoising error will gradually increase.Therefore,this paper proposes to filter the outliers and background noise of SNPP-VⅡRS nighttime lights images using a combination of median filtering and low threshold denoising,and the correlation between the total amount of nighttime light after denoising and GDP is analyzed and the accuracy is verified.Experimental results show that the correlation between the total amount of nighttime light collected by median filtering and low threshold denoising and GDP is superior to the traditional method,and the precision of the brightness estimated by the model established by this method is higher,reflecting that the method has a higher denoising precision.

Aircraft target recognition in remote sensing image combined saliency map with deep learning

LIU Xiangyun, GONG Zhihui, JIN Fei, YANG Guang, FAN Weikang

2019, 0(3):  27-31.  doi:10.13474/j.cnki.11-2246.2019.0072

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In order to identify the aircraft target in high resolution remote sensing image accurately and quickly,a kind of aircraft target recognition algorithm combined the saliency map with the deep belief networks is proposed.First,the salient object in the image is extracted by use of histogram-based contrast method;Second,the candidate target is located by locating connected region;Then the color moment,Hu invariant moments,Tamura texture features and the edge direction histogram of candidate target is extracted.Last,the normalized feature is applied to deep belief networks to recognize the target.Experimental results show that the detection rate of the algorithm is 98.46% and the false alarm rate is 5.20%.Multi-feature provides more information than single-feature,and the ability of target recognition and anti-interference is improved.

Adaptive fuzzy threshold method wavelet denoising of GF-2 satellite image

ZHANG Yuhang, YANG Wunian, REN Jintong, DENG Xiaoyu

2019, 0(3):  32-35.  doi:10.13474/j.cnki.11-2246.2019.0073

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GF-2 satellite images provide abundant image information,and the releasing of high-resolution image data has broken the long-term dependence of China's high resolution data on land observation.However,the image can be disturbed in the process of transmission and preservation,and if the area of interest is polluted,the image information in the region cannot be fully used.In order to solve the difficult problem of the GF-2 remote sensing image denoising,this paper adopts adaptive fuzzy threshold denoising methods,which is based on various scales noise variance adaptive fuzzy threshold function of nonlinear processing,restructuring as a new wavelet coefficients,the denoised image is obtained by inverse transformation of the wavelet.Compared with average filtering,gaussian smoothing filter,median filter,filtering,wavelet threshold denoising and Birge-Massart strategy denoising threshold value method,the results show that the adaptive fuzzy threshold denoising method is fully combined with hard and soft threshold processing method that both retains the image details and makes the image more smooth.The image that is denoised by this method can preserve overall information,the denoising effect is highly desirable.

Multi-source image fusion building 3D model unobstructed texture automatic mapping method

LI Zhicheng, WANG Weixi, LI Xiaoming, BIAN Yufan, QIAN Jianguo, TANG Shengjun

2019, 0(3):  36-40.  doi:10.13474/j.cnki.11-2246.2019.0074

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The application of tilt photogrammetry in the construction of digital city is introduced in this paper.In view of the occlusion problem of texture map in the current 3D reconstruction process based on oblique photogrammetry,the geometric principle of texture occlusion is explored in detail,and the high-altitude tilt photography of joint fixed-wing aircraft is proposed to design the unobstructed image optimization algorithm for the 3D model of the building,by which the high-precision unshielded texture automatic map can be realized and verified through experiments.

Simplification of building polygon based on adjacent five-point method

LI Lili, LI Chengming, LU Xiaoping, YIN Yong, WU Pengda

2019, 0(3):  41-45.  doi:10.13474/j.cnki.11-2246.2019.0075

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According to the fact that the traditional building simplify algorithm can not accurately maintain the details of the local geometric characteristics of buildings,introducing a sharp convex angle and other issues,a building polygon simplification method is proposed based on the adjacent five points in this paper.By defining the adjacent five points on the boundary of the polygon as the basic processing unit,the basic unit is divided into 4 types:Z parallel,Z non-parallel,U parallel and U non-parallel,to simplify progressively,and sharpen the corners generated during the reduction process taking into account the angular constraints.Experiments are conducted with the polygon data of a 1:10 000 actual building in a certain area.The results show that the proposed algorithm can avoid sharp corners as much as possible on the basis of maintaining the basic geometry features of the building,and results are more in line with human visual perception.

Above-ground biomass estimation of provincial scattered grassland based on Google Earth Engine and machine learning

XIU Xiaomin, ZHOU Shufang, CHEN Qian, MENG Jihua, DONG Wenquan, YANG Guangbin, LI Xiaosong

2019, 0(3):  46-52,75.  doi:10.13474/j.cnki.11-2246.2019.0076

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Estimating above-ground biomass of grassland in large areas is of great significance for grassland resource utilization,management and global carbon cycle research.In order to pursue efficient and rapid estimation of above-ground biomass of provincial scattered grassland,this study selected Anhui province as the research area,built the relationship between Landsat8 OLI,auxiliary data and measured above-ground biomass data through machine learning and Google Earth Engine (GEE) platform.The main results showed that the model which constructed by spectral information,terrain factors and machine learning had obvious advantages,the estimated accuracy was more than 65%.The classification and regression tree (CART) model R² was 0.57,the estimated accuracy was 68.60%.Support vector machine (SVM) model R² was 0.59,the estimated accuracy was 75.74%.The GEE platform has rich and available data,it can complete pre-processing and calculation analysis efficiently.The combination of GEE and ground survey data has the potential to estimate above-ground biomass of scattered grassland on a national scale.

An improved mean-valued method of adaptive median filter

SHUAI Murong, LIAO Xiuying, CHENG Hui, XIE Yiwen, YANG Pengfei

2019, 0(3):  53-56,90.  doi:10.13474/j.cnki.11-2246.2019.0077

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To deal with the deficiency in terms of de-noising and preserving image details of the adaptive median filter,an improved mean-valued method of adaptive median filtering (IMAMF) is proposed.The algorithm adopts the way of extending edge of the image,so that all the pixels of the original image can be detected by noise detection factor and filtering under the adaptive window.When noise and signal are detected,the noise threshold is increased.If the pixels with noise are corrected,the new average filter value is output.Otherwise,the signal point is output with the original gray value.In order to verify the feasibility of the algorithm,five different algorithms are used for simulation analysis.From the subjective and objective angles of different algorithms for comparative analysis,the experimental results show that the algorithm can not only effectively filter out salt and pepper noise in the range of 10% to 90%,but also can better preserve the details and edge information of the original image.Obviously,the new method has better properties.

Geo-positioning of domestic satellite images with reference image using total least squares adjustment

PAN Xuechen, JIANG Ting, YU Anzhu, WANG Xin

2019, 0(3):  57-60.  doi:10.13474/j.cnki.11-2246.2019.0078

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Considering the lack of ground control data of domestic remote sensing images,a method of using reference image data geo-positioning to increase accuracy of geo-positioning was proposed.Meanwhile,considering random errors in coefficient matrix of observation equation for image points,the total least squares was introduced to achieve a more reasonable result.The experimental results of ZY-3 and TH-1 images indicated the feasibility and availability of proposed method.

Cloud detection method of FY-2G satellite images based on random forest

FU Hualian, FENG Jie, LI Jun, LIU Jun

2019, 0(3):  61-66.  doi:10.13474/j.cnki.11-2246.2019.0079

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According to the principle of cloud detection in remote sensing images,a method based on the random forest was proposed in this paper and applied to FY-2G images.Combining the cloud inspection product of the National Meteorological Satellite Center (NSMC) for accuracy testing of the algorithm,the accuracy test of the cloud detection shows that the Probability of Detection (POD) is 88.32%,the minimum False Alarm Rate (FAR) is 9.36%,and the Critical Success Index (CSI) is 80.14%.The results show that the method can improve the accuracy of cloud detection effectively,and identify the partial misjudgment in NSMC correctly.

Research on break-through error simulated estimation of underground traverse with gyro observation in an immersed tunnel

MA Ji, SHI Zhen, ZHANG Xuewei

2019, 0(3):  67-70,102.  doi:10.13474/j.cnki.11-2246.2019.0080

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The mutual compensation of random errors is often neglected in traditional analytical method of break-through error estimation for underground traverse with gyro observation,and it leads to an overestimation of the error.Based on Monte Carlo random simulation technology,a break-through error estimation method is proposed.The method is tested on an equivalent mock-up network of the tunnels associated with the Hong Kong-Zhuhai-Macau Bridge.The results prove that the proposed method could effectively estimate break-through error,and has a good application effect for underground traverse with gyro observation.

The determination of building inclining state based on subregional regression model

CHEN Meng, DU Zhixing, ZHANG Tao

2019, 0(3):  71-75.  doi:10.13474/j.cnki.11-2246.2019.0081

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According to the complicated structures of the city high-rise buildings and the difficulty of setting up instruments externally,this paper puts forward subregional regression model to determine building inclining state through fitting surface of foundation settlement.The monitoring points were equably distributed on the building foundation,whose settlement was measured periodically.Fitting each block of foundation settlement,the local deformation features were obtained.According to the features,the deformation regions were divided.Finally,the oblique angle and direction of buildings were calculated through the normal vector of fitting surface.Compared with traditional tilt observation methods,results show that subregional regression model can meet the actual engineering requirements and it has better precision and feasibility than regression plane model.

Application of new FMCW ground-based SAR and three-dimensional laser scanner in dam deformation monitoring

LIU Longlong, ZHANG Jixian, WANG Shijie, ZHAO Zheng

2019, 0(3):  76-80.  doi:10.13474/j.cnki.11-2246.2019.0082

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In order to solve the disadvantages of traditional dam deformation monitoring method,including only getting point deformation information,high monitoring costs and significant environmental impact,this study introduces a new monitoring technology for ground based synthetic aperture radar (GBSAR).The low visibility of radar data can be solved by the combination of high-precision two-dimensional deformation map obtained by Fast-GBSAR and DEM generated by three-dimensional laser scanner.Through monitoring of a domestic dam and in-depth analysis of deformation reasons using this technology,we propose that the tide in the reservoir area has a cyclical effect on the horizontal deformation of the dam.The result indicates that the high-precision dam deformation information can be obtained by Fast-GBSAR.In this study,a three-dimensional monitoring method with intuitive,efficient and high-precision is established,combined with three-dimensional visualization technology,and it provides reliable support for dam deformation monitoring.

Research on ontology driven map symbol sharing method

ZHOU Haixia, HUO Liang, ZHU Jie, HU Xiao, FAN Longfei

2019, 0(3):  81-85.  doi:10.13474/j.cnki.11-2246.2019.0083

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Aiming at the incompatibility between the map symbol model and the heterogeneous map symbol resources,it is difficult to realize the integration and interoperability of multi-source heterogeneous map symbols under the network environment.This paper proposes a map symbol conceptual model based on the ontology.By defining the classes,attributes,relationships and constraints of symbols,the model realizes the formal expression of symbolic concepts and relationships and the construction of symbol ontology.On this basis,based on the SOA software architecture idea,a map symbol distributed sharing framework structure based on Web service is established to realize cross-platform calling of symbols.Based on the cross-platform calls between XML Web Services map symbols and ArcEngine,the feasibility experiment of this symbols sharing method is carried out.The results show that the proposed method can realize the flexible and open integration and interoperability of multi-source heterogeneous map symbols under the network environment,and effectively preserve the semantic information of map symbols.

Implementation of real-time horizontal displacement monitoring for Android devices

OUYANG Chenhao, HUANG Yongshuai, LIU Guanlan, SHI Junbo

2019, 0(3):  86-90.  doi:10.13474/j.cnki.11-2246.2019.0084

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Horizontal displacement monitoring plays an important role in rail transit engineering.With the development of mobile Internet and smart devices,especially their applications in horizontal displacement monitoring,real-time monitoring data retrieval and data security issues become increasingly important.In this paper,a real-time horizontal displacement monitoring mobile application for Android device is introduced.With bluetooth and network communication functions built in Android device,the monitoring equipment,the Android device and the monitoring information service platform are connected together,which ensures real-time monitoring data retrieval.On the other hand,embedding with data encryption algorithm ensures the data security.Applying the developed software in practical rail transit projects shows that the software can collect and process monitoring data in real time which improves the monitoring efficiency.By encrypting monitoring data,the data security issue can also be resolved.

S-100 hydrographic geospatial data model review

LUO Jianan, WAN Xiaoxia, SUN Dongli, WU Jin, XU Weiguo, LIU Liwen, DUAN Jing

2019, 0(3):  91-97,112.  doi:10.13474/j.cnki.11-2246.2019.0085

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The aim of this review is to fully understand the current development status,existing problems and the next research focus of the S-100 hydrographic geospatial data model.By collecting and sorting out the domestic and foreign research documents and technical materials related to the S-100,the S-100 research is divided into three stages according to the time series.This paper expounds and analyzes the research results in the theoretical research stage and the applied research stage,and puts forward seven key research directions in the innovative research stage.

An automatic calibration method for vector map plane accuracy based on SSW point cloud

QIANG Xinlin, LI Guangwei, WANG Liuzhao, ZHANG Weihong

2019, 0(3):  98-102.  doi:10.13474/j.cnki.11-2246.2019.0086

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Routine calibration of vector maps is based on sampling and field measurement,with much workload and low automation.To solve this problem,automatic calibration method for vector map plane accuracy based on SSW laser point cloud data is presented.First of all,the vehicle laser scanner is used to obtain the high precision point cloud data on both sides of the road.The point cloud data is filtered,transformed coordinate and verified accuracy.Secondly,based on multi-feature recognition algorithm,SWDY software is used to extract point cloud feature points.Finally,the nearest neighbor method is used to search the same class of featured points and line,the mean square error of matched points and line is calculated.This method is used to verify plane accuracy of vector map with 1:1000 measuring scale in Xinghua city.The experimental results show that 201 of the 205 feature features of the point cloud data are successfully matched.The overall error of the vector map is 0.26 m,and the acquisition and leakage and the obvious error in the vector map can be found.The method can reduce the field workload of existing detection methods,increase the quantity of testing sample,and lower human disturbance factors in the process of detection,which effectively improve the reliability and efficiency of detection.

Climate response of NDVI index on Qinling Mountains in 25 years

CHEN Xiaoning, JIANG Haochen

2019, 0(3):  103-107.  doi:10.13474/j.cnki.11-2246.2019.0087

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Using vegetation index and four meteorological stations'air temperature,precipitation data of the research area in 1982 to 2006,the paper researches vegetation index,the temperature and precipitation change tendency of qinling region in shaanxi,analyzes the correlation between vegetation index and the temperature or precipitation.Using the vegetation type data analysize the related degree between different vegetation types of NDVI and different climate factors.The results show that from 1982 to 2006,the research area average annual temperature is an obvious rise,rise up to 2.1℃,the annual total rainfall of every 10 years down about 72 mm,NDVI in qinling region increases slightly.Overall,the correlation between the changes of vegetation index and temperature in the middle region is the largest,decreasing on both sides and the correlation between rainfall is minimum in the middle,increment on both sides.Temperature has the greatest influence on orchard and economic forest,precipitation has the greatest impact on broad-leaved forests.The temperature is the main factors influencing the changes of vegetation index in the region.

A high precision automatic pricking control point method based on DOM and DEM

WANG Mingming, WANG Jia, FENG Zhongke, SHEN Chaoyong

2019, 0(3):  108-112.  doi:10.13474/j.cnki.11-2246.2019.0088

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Referring to the basic geographic data updating requirements,in order to eliminate the field work in laying control points,reduce the office workload in pricking points and improve the precision and density of control points,this paper presents a method based on existing DOM and DEM data by using IPS and auxiliary software to realize high-precision automatic pricking control points.Clipping the existing DOM according to specific matching requirements,loading the DOM and the images into IPS at the same time to match tie points,calculating the object space coordinates of the matched points according to DOM graphic reference,tie points image coordinates,TFW file and DEM.Removing the error points through adjustment detection and visual inspection,then changing the attribute of the matched points to complete the work of pricking control points.After that,we can continue processing in IPS to complete the steps of aerial triangulation,geographic information product production etc.,or export and convert them into other software format for subsequent processing.

A nowcasting method based on satellite remote sensing

LIU Jia

2019, 0(3):  113-115,119.  doi:10.13474/j.cnki.11-2246.2019.0089

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MCS (mesoscale convective system) is the main reason of formation strong convective weather.The main problem of existing tracking and forecasting algorithms is unphysical split and merger of cloud clusters within the life cycle of MCS.To address this problem,FCC (forecasting convective cells) method is proposed.Displacement of the geometrical centroid is utilized to forecast the movement of convective cells in FCC algorithm using FY-2 satellite data.Case studies show that convective cells are forecasted efficiently in different phases of MCS lifecycle including genesis,maturity and dissipation using FCC algorithm.Moreover,contingency tables method applied to various case studies show that proposed algorithm efficiently and accurately.

Urban water body information extraction base on the multi-temporal contour shadow difference

OU Jianbin, LUO Wenfei, LIU Chang

2019, 0(3):  116-119.  doi:10.13474/j.cnki.11-2246.2019.0090

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How to solve the problem of water and shadow mixing in urban area is important but difficult.However,the difference between the position and shape of the shadow contour at different time provide a potential way to solve this problem.The objective of this study is to propose a method of urban water body information extraction base on the multi-temporal shadow contour difference (WMSD).Two remote sensing images of GF-1 and Landsat 8 were used to test this propose method in Tianhe District,Guangzhou.At the same time,we used some methods of NDWI,MNDWI and SWI to extract water information in this same area,and carried out precision comparative analysis.Study results show that the classification accuracy of WMSD is over 88%,and compared with NDWI,SWI and MNDWI methods,the accuracy of WMSD increase by 8.50%,9.50% and 4.67% respectively,which proves that the WMSD method can solve the problem of the confusion between the shadow and the water extraction information,and can be a feasible method for the extraction of urban water body by remote sensing information.

A method of extracting water boundary using hyper spectral pixel decomposition technique

ZHOU Wei, GUAN Hongjun, TONG Jun

2019, 0(3):  120-123,140.  doi:10.13474/j.cnki.11-2246.2019.0091

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A water boundary extraction method based on hyper spectral mixed pixel decomposition is proposed in this paper to solve the problem of precision loss caused by water boundary mixed pixel.The method which is combined with the spectral characteristics of the hyper spectral images obtains the mixed pixels of the water boundary with weakening the impact of many factors on the pixel boundary recognition to reduce the computation amount of the mixed pixel decomposition.The precision of the boundary definition of water body can be significantly improved by approaching the true boundary of the water body with the high precision decomposition of mixed pixel and the segmentation of water boundary pixel.The experimental results show that the accuracy of the method is better than that of the water index method,which is slightly better than the support vector machine.The overall accuracy of this method is 93.86%,and the Kappa coefficient is 0.87.

Research on key technologies of acquisition of airborne LiDAR point cloud data and high-precision DEM

YANG Huishan, LEI Lizhen

2019, 0(3):  124-127.  doi:10.13474/j.cnki.11-2246.2019.0092

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This paper introduces the general technical route based on the airborne LiDAR point cloud data acquisition and high-precision DEM construction in Guangdong Province.For solving the difficulties,the paper researched some key technologies and solutions from five aspects:equipment selection,point cloud density design,data obtained method in mountainous areas covered densely,point cloud data classification and combination algorithm,and blank area processing.Research of this paper will be beneficial for the design and implementation of similar projects.

Design of landslide monitoring cloud platform based on cloud computing technology:taking Jingyang as an example

WANG Yipeng, ZHANG Yongzhi, ZHAO Chaoying, LI Yulei, ZHANG Tengfei

2019, 0(3):  128-132,136.  doi:10.13474/j.cnki.11-2246.2019.0093

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This paper analyzed and discussed the software architecture and key technology of the landslide disaster monitoring cloud platform,based on the data processing and related theory and tecnology.The software architecture of landslide monitoring cloud platform and detailed function module in the core layer of Jingyang county landslide in Shaanxi province was employed as an example.The paltform also reserved the application programming interface to users.In addition,this paper also analyzed the advantages and disadvantages of the landslide monitoring cloud platform,providing certain research and reference value for the future designing and implementation of other geological disaster monitoring cloud platform.

The new method of inclination deformation monitoring of tower building

WANG Na, DUAN Longfei, XU Weidong, WANG Zhiyi

2019, 0(3):  133-136.  doi:10.13474/j.cnki.11-2246.2019.0094

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With the greatly increasing of the tower building from place to place,the potential risk caused by the deformation of the tower building has been taken more and more attention.In view of limitations and inefficiency of the traditional methods,this paper puts forward the new method of inclination monitoring of tower building based on point cloud data generated by 3D laser scanner.Firstly,we need to capture point cloud of target object using two set of different 3D laser scanner.Secondly using the point cloud to build tower building ground surface model.Thirdly,generating central point along the axis direction and filtering the correct point group.At last,calculating the offset and amount of inclination with high accuracy of target object.In addition,we also program to realize the output of calculation result just by one key.It turns out that the angle error between the new method and traditional method is separately 0.005° and 0.001°.The amount of inclination is separately 0.000 05 and 0.000 1 m.This method could not only quickly obtain offset variation characteristics of target object and part of them,but also could provide the foundation data model for the construction,maintenance and reconstruction of them.

Research on 3D scan debris reconstruction by using artificial fish algorithm

LIU Ensheng, CHENG Xiaojun, HUANG Yuhua

2019, 0(3):  137-140.  doi:10.13474/j.cnki.11-2246.2019.0095

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Previous approaches for reconstructing fragments rely mainly on a single characteristic and thus may cause accumulative errors.In this paper,we present a global optimal matching method for 3D fragments by using artificial fish school algorithm.The proposed method first extracts multi-featured elements from the point cloud of the fragments.Combined with texture and expert knowledge,rough set theory is then applied to classify multiple types of fragments.The artificial fish school algorithm is subsequently adopted to achieve optimal matching results.Results indicate that the proposed method is powerful,robust,and independent of initial position.The proposed method can be a new efficient tool for the global matching of fragments.

Analysis on spatial-temporal change monitoring of urban resilience

MAO Weiqing, XIA Lanfang

2019, 0(3):  141-144.  doi:10.13474/j.cnki.11-2246.2019.0096

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Based on the achievements of the geographical conditions census,this paper adopts a method of spatial-temporal change monitoring to evaluate urban resiliences and provides technical support for the construction of resilient urban.Firstly,this paper studies the integration of multi-source heterogeneous spatial-temporal geographic data,and establishes resilience database of urban space.Then,using the advanced technologies such as GIS,DSM and remote sensing image recognition,the basic urban resilience is studied from space dimension and time dimension.And then,the urban high-risk storage distribution and monitoring methods are taken as an example to monitor the urban resilience in special area.Finally,from the time dimension,the change monitoring of urban resilience is studied.In conclusion,the method described in this paper will greatly enhance the ability of geographic information to resilience urban construction.

Precision analysis of BIM layout and construction results based on MS60

DENG Mingjing, RAN Dong, YANG Zhongxuan, HUANG Heng, LI Changyi

2019, 0(3):  145-147,162.  doi:10.13474/j.cnki.11-2246.2019.0097

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With the emergence of various special-shaped buildings,the traditional construction lofting methods and detection techniques can not fully meet the construction requirements,so it is necessary to introduce new construction lofting and detection techniques.Based on the project of Chongqing Xiantao Data Valley financial building,this paper uses MS60 BIM lofting and 3D laser scanning technology to explore its high efficiency and reliability in the construction of special-shaped building and the result detection.In this paper,first of all,in the process of construction lofting,by selecting the layout points on the BIM model and using the MS60 scanner to search and track automatically,the process of construction lofting is simplified,and then the surface deviation analysis of the BIM model and the point cloud data is used.The result of construction is analyzed with high precision,which provides a reference for subsequent construction.

Application of high precision scanner in subway tunnel construction

Peter XU, WANG Lei, LU Ronghai, ZHU Shuipeng

2019, 0(3):  148-150.  doi:10.13474/j.cnki.11-2246.2019.0098

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Taking Beijing Metro Line 7 as an example,this paper introduces a new method by using three-dimensional laser scanning technology to measure the present situation of tunnel excavation in the complex geological environment,to determine the overbreak and underbreak of the tunnel,and to monitor the risks of the tunnel construction to prevent the occurrence of tunnel collapse accident,etc.The method can be widely used in tunnel section measurement and other related construction projects in metro and other industries.

Research on illegal mining monitoring based on UAV aerial survey technology

LI Tao, GAO Bo, ZHANG Yuntao, GAO Jiajia

2019, 0(3):  151-154.  doi:10.13474/j.cnki.11-2246.2019.0099

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Due to the wide coverage of rivers and lakes,long lines,large volume,and many problems left over from history,there are many difficulties in using conventional measurement methods.Combining with the practical engineering case,the Sirius UAV aerial survey method,the paper demonstrates the feasibility and effectiveness of the new scheme.The advantages of image-free Sirius UAV in river and lake delimitation and the significance of multi-purpose mapping of high-precision aerial survey results are expounded.It can be used as a reference for similar projects.

A datum feature extraction and deformation analysis method based on normal vector of point cloud

SUN Wenxiao, WANG Jian, JIN Fengxiang, LIANG Zhouyan

2019, 0(3):  155-158,162.  doi:10.13474/j.cnki.11-2246.2019.0100

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In order to solve the problems of the existing difficulty of datum feature extraction and the lack of applicable analysis method of point cloud data in the application of three-dimensional laser scanning technology to the field of deformation monitoring,an efficient method for datum feature extraction and deformation analysis is proposed in this paper based on normal vector of point cloud.Firstly,owing to the local surface fitting obtains directly the geometric features by applying the point cloud model with low time complexity,this paper uses the local planar normal vector determined by the nearest neighbours of meet certain condition and follow the normal vector of the point cloud to detect the datum points.Then,the cubic B-spline curve fitting is performed on the datum points.To this end,elevation of the datum and the inclination angle of the radial point are calculated according to the fitted curve and then the deformation information is analyzed.The proposed approach is verified on real large-scale tank data set captured with terrestrial laser scanner in a chemical plant.The results show that the method could obtain the entire information of the monitor object quickly and comprehensively,and reflect the datum deformation accurately.

Application of precision trigonometric elevation measurement in river-crossing leveling based on autocollimation total station

HAO Dan, WANG Fen

2019, 0(3):  159-162.  doi:10.13474/j.cnki.11-2246.2019.0101

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With the development of fully automatic intelligent total station and the gradual elimination of optical level,precise trigonometric leveling has been widely used in river-crossing elevation transfer.This paper detailed the principle and steps of quadrilateral river-crossing leveling method based on precise trigonometric leveling with fully automatic total station.In addition,this method carried out theoretical derivation and precision analysis of the height difference between river-crossing points obtained by directional observation,and it was proved that this method could be used in the second-class river-crossing leveling under the condition of controlling a certain cross-river distance and taking corresponding measures to eliminate other errors.Finally,an experiment showed that the method could meet the accuracy requirements of second-class river-crossing leveling.