Table of Content

25 March 2020, Volume 0 Issue 3

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Aircraft target recognition based on saliency detection and feature matching

OUYANG Huan, FAN Dazhao, GUO Jing, DAI Yazhen

2020, 0(3):  1-6.  doi:10.13474/j.cnki.11-2246.2020.0067

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According to the difference of visual saliency between target and background together with the morphological characteristics of the aircrafts, this paper proposes a novel aircraft target recognition algorithm based on saliency detection. The algorithm first detects the saliency of the pre-processed remote sensing image and eliminates the influence of shadow for the region of interest extraction. Distinguish the region of interest based on the morphological characteristics of the aircrafts, and then achieve aircraft target recognition. Finally, calculates the aircraft fuselage length, wingspan and relative moments. Afterwards, the aircraft type discrimination can be achieved via feature matching. Extensive experiments show that the algorithm has accurate feature extraction results and high target recognition accuracy.

Monocular vision coordinate transfer method with IMU aiding

GUO Ruonan, JIANG Junxiang, NIU Xiaoji, SHI Junbo

2020, 0(3):  7-11.  doi:10.13474/j.cnki.11-2246.2020.0068

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Aiming at the scene that GNSS RTK can not provide coordinates due to signal occlusion or difficult station erection during pipeline measurement, this paper proposes a monocular vision coordinate transfer method with IMU aiding. Firstly,the camera is set up at two known RTK points to capture imagesand the IMU data is collected simultaneously. Then extracting and matching image features, restoring relative rotation, transition and scale. Finally triangulating the point to be measured, the coordinate of the point in the camera coordinate system of the real scale can be obtained. Referring to the initial alignment method of the IMU static base, projection of gravity vector and the optical center vector between the cameras in the geographic coordinate system and the camera coordinate system can be used to solve the rotation matrix between the two coordinate systems, and further obtain the the three-dimensional coordinates of the point to be measured in the geographic coordinate system. Compared with other measurement methods, the method is flexible and convenient, the device is light, and the operation is simple. And we can obtain any coordinate in the camera field of view with a single measurement.The experimental results show that the error average of the horizontal coordinate is 0.12 m, and the error average of the elevation is 0.2 m.

Automatic extraction of small mountain river information and width based on China-made GF-1 satellites remote sensing images

XUE Yuan, LI Dan, WU Baosheng, FU Xudong

2020, 0(3):  12-16.  doi:10.13474/j.cnki.11-2246.2020.0069

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Extraction of high-resolution geomorphic information from remote sensing images is a key technology for supporting the research of mountain rivers. In this research, we propose a DEM-aided approach based on object-based image analysis and improved decision tree classification for water information extraction and present a method for automatic extraction of small river width. We used the 1421 km² area of upstream of Huangfuchuan River Basin on the Loess Plateau, China, as a case study area. The China-made GF-1 satellite images and the DEM data are implemented as the secondary data source. The results show that the proposed method has a total accuracy as 89.5%. For extremely small rivers with width ranging from 0 to 10 meters, the error of river width extraction by our method is 18.54%. The extraction error of small rivers whose width ranging from 10 to 30 meters is 12.07%.

Cloud detection for remote sensing images using improved U-Net

ZHANG Yonghong, CAI Pengyan, TAO Runzhe, WANG Jiangeng, TIAN Wei

2020, 0(3):  17-20,34.  doi:10.13474/j.cnki.11-2246.2020.0070

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An improved U-Net model is proposed to solve the problem that missing detection of fragmentary clouds and thin clouds when U-Net is applied to detect clouds, and applied to cloud detection of FY-4A data. Firstly, the cloud inspection product of the National Meteorological Satellite Center is used to generate binary cloud label. Secondly, the encoder of U-Net is combined with residual block to share parameters and avoid degradation of deep network. Finally, the dense block is integrated into the decoder to connect the shallow features with the deep features, which is conducive to acquiring new features and improving the utilization rate of features. The experimental results show that the IOU and Dice coefficients of the model on the test set are 91.5% and 95.2% respectively, which can detect thin clouds and a large number of broken clouds well, and the effect is obviously better than that of the U-Net model.

Chlorophyll hyperspectral inversion with PRO-4SAIL and BP neural networks

GUO Yunkai, XU Min, ZHANG Xiaojiong, LIU Yuling

2020, 0(3):  21-24.  doi:10.13474/j.cnki.11-2246.2020.0071

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In view of the problems of over-fitting and low prediction accuracy of chlorophyll inversion by the PRO-4SAIL radiation transfer model coupled with BP neural network, there are some problems.In this paper, measured hyperspectral data and simulated spectral data in the research area are used as data sources, and some measured sample data are added to the training set composed of simulated sample data to build the BP neural network chlorophyll inversion model, and the model verification and accuracy evaluation are carried out with additional measured data.The results show that the training concentration can solve the over-fitting problem of chlorophyll inversion model by adding a small amount of measured data, improve the accuracy of chlorophyll content prediction, and accurately invert the vegetation information of roadways, which can be applied to the remote sensing monitoring and evaluation of roadways environment.

On-orbit geometry calibration of microsatellite area-array images based on attitude linearity error

WANG Lang, YOU Hongjian, WANG Huixian

2020, 0(3):  25-28.  doi:10.13474/j.cnki.11-2246.2020.0072

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The microsatellite has low accuracy of attitude and position measuring equipment, due to the limitations of platform volume, weight and energy, which results in large direct positioning error. Through the calibration of the constant angular error of the multi-view images in the Songshan area, we found that the system error of attitude angle varies linearly with time. This paper proposes an on-orbit geometry calibration model based on two-dimensional direction angle of detector and offset matrix with attitude linearity error to improve the positioning accuracy. Compared with the traditional constant angular model, this paper considers the law of linear variation of attitude angle system with time. The experimental results show that after the internal and external orientation elements are calibrated, the positioning accuracy of the satellite is increased from tens of kilometers to less than ten meters. The proposed calibration model effectively eliminates the system error of attitude angle varying linearly with time compared with the traditional constant angular model.

Generative adversarial networks for hyperspectral image classification

ZHANG Pengqiang, LIU Bing, YU Xuchu, TAN Xiong, YANG Fan, ZHOU Zenghua

2020, 0(3):  29-34.  doi:10.13474/j.cnki.11-2246.2020.0073

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In order to improve the classification accuracy of hyperspectral images, a novel hyperspectral image classification method based on generative adversarial network is proposed. The proposed generative adversarial network consists of generator, discriminator and classifier, in which the generator is used to approximate the data distribution of hyperspectral samples and generate specific categories of samples. The discriminator is a binary classifier to determine whether the input samples are real data. And the classifier is used to classify the input samples. The parameters of generator, discriminator and classifier are updated sequentially by back propagation algorithm to minimize the loss function, so as to achieve the goal of training the network. Generators and discriminators can approximate the sample distribution of hyperspectral images to assist the training of the classifier. Therefore, they can effectively improve the classification accuracy of hyperspectral images. Pavia University and Salinas hyperspectral data sets are used for classification experiments respectively. The experimental results show that the proposed classification method can effectively improve the classification accuracy of hyperspectral images with only small samples.

Monitoring of 3D deformation of target by ground-based synthetic aperture radar

JIANG Liubing, YANG Kai, CHE Li

2020, 0(3):  35-38,68.  doi:10.13474/j.cnki.11-2246.2020.0074

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Deformation monitoring is an important way of early warning before the calamity accidents happen, such as variouslarge-scale building collapse, bridge collapse, landslide and others. Ground-based interferometric synthetic aperture radar has obvious advantages and been widely used in various methods of deformation monitoring. Aiming at the problem that GB-SAR can only measure one-dimensional deformation of targets, the concept of parallel synthetic aperture radar is proposed. Based on the two-dimensional displacement obtained by multi-aperture interferometry and integrated the target displacement date monitored by parallel radar, the three-dimensional displacement information of the target is obtained by accurately calculation, which can reflect the real displacement of target, which is of great significance for the monitoring and diagnosis of the structural performance of the building.

Height time series change of China coastal GNSS stations using CEEMD

LIU Hao, ZHOU Dongxu, WANG Panlong, ZHANG Huayi, WANG Yongkang, JIANG Chuanling

2020, 0(3):  39-43,77.  doi:10.13474/j.cnki.11-2246.2020.0075

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The height time series data of six GNSS reference stations (2010—2018) in coastal areas of China are processed and analyzed by using the complete empirical mode decomposition method (CEEMD). The results show that:CEEMD has certain advantages in the analysis of height time series, which can accurately decompose the period of the week, month, season and year in the height timing of each GNSS station, and the annual movement is the main contribution, the short-period change of the height time series of each station is closely related to the tidal change cycle. The ground subsidence of coastal GNSS stations has both regional consistency and inter-regional differences,the DBJO and DZJJ stations in the East China Sea showed a trend of decreasing first and then rising,the NZUH and NWZU stations in South China Sea District showed a downward trend, and the BZMW in the Bohai Sea area showed an upward trend, while the BLHT stations in the same area showed a significant downward trend.

Allan variance simplification algorithm based on RWTLS

ZHOU Xiaomin, LIU Haiying, ZHANG Junjie

2020, 0(3):  44-47,82.  doi:10.13474/j.cnki.11-2246.2020.0076

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Now,Allan variance is the most widely used method for random error identification. Allan variance can effectively separate random errors in the navigation process. But Allan variance also has its own limitations. Allan variance calculation inefficient when dealing with the high-volume. Allan variance is affected by the gross error. This article put forward the solution of simplified Allan variance algorithm. First, a simplified Allan variance algorithm which can both reduce thecalculation burden and keep the accuracy of the results is proposed.Then taking advantage of robust weighted overall least-squares (RWTLS) iterative algorithm of the model of simplified Allan variance identification results are poor resistance fitting processing. Finally with optical fiber type inertial measurement unit (IMU) as the analysis object, experiment scheme to verify this simplified Allan variance is designed.

A space-time visualization analysis method for urban public bicycles connecting to the subway

GAO Zhiwen, ZHANG Xuedong, XU Zhijie, ZHANG Jianqin, SHEN Zhaomu, GUO Xiaogang, YANG Ming

2020, 0(3):  48-55.  doi:10.13474/j.cnki.11-2246.2020.0077

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Public bicycle is an important connection method for urban rail transit. In order to show the time and space characteristics of public bicycle connection subway travel more clearly and intuitively, this paper proposes a time-space visual analysis method for public bicycle rental point to connect passenger traffic. The method firstly preprocesses and analyzes the IC card data of subway passenger flow and public bicycle, and analyzes the time series similarity between the two. Then, through the time cluster analysis of subway passenger flow, three types of travel day are obtained. Respectively, feature visualization and spatial information visualization for the correlation calculation results of each type of travel day, to achieve a comprehensive analysis of the time and space characteristics of public bicycle access subway travel. Finally, the method is used to Xuanwumen subway station in Xicheng District, Beijing, a time-space visual analysis of the public bicycle connection subway travel within a reasonable range of the station was carried out. The results show that the visual analysis of the integration of subway passenger flow and public bicycle IC card data can more comprehensively and dynamically grasp the spatial and temporal distribution of urban public bicycle connection subway travel. This method can be used for the planning of public bicycle rental points at urban rail transit stations and construction provides a quantitative basis.

Study on the influence of scale change on the relationship between urban ecological environment and human activities

CHENG Penggen, YUE Chen, WEI Xiaojian, ZHOU Jiangwen

2020, 0(3):  56-63.  doi:10.13474/j.cnki.11-2246.2020.0078

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In view of the research on the impact of spatial scale on urban ecological environment and human activities, this paper takes Nanchang City as the research area and divides three grid scales of 300×300, 500×500 and 700×700. Using the remote sensing ecological index RSEI (target vector) to quantify the urban ecological environment quality, combined with POI points, Weibo check-in points and road network data (feature vectors), the random forest regression model is used to analyze the fitting effect between the two scales. The results show that: ①RSEI and POI points, Weibo check-in points and road network have strong negative correlation at three scales; and the negative correlation is RSEI and Weibo check-in point data, and the worst is RSEI and road network data. ②The random forest regression model at 300×300 scale has the best fitting effect. As the scale becomes larger, the effect of the fit will get worse. ③Regardless of the scale change, the standardized residuals fitted by random forest regression show a normal distribution; and as the scale becomes larger, the randomness of the standardized residuals space distribution also increases. The random forest regression model provides an effective way for the relationship between urban ecological environment and human activities, and provides a scientific basis and reference for urban ecological civilization construction.

Fast calculation of large-scale global illumination optimized by multi-level storage strategy

QI Shuang, YU Guangji

2020, 0(3):  64-68.  doi:10.13474/j.cnki.11-2246.2020.0079

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Aiming at the problem of large amount of global illumination calculation for large-scale complex scene rendering, an improved voxel cone tracking global illumination algorithm based on multi-level resolution texture storage structure is proposed. Firstly, a multi-level texture storage structure based on human visual characteristics to efficiently store lighting information is used. And then, in the direct lighting calculation, combined with the characteristics of the storage result, a combination of GPU hardware acceleration of hybrid storage and software acceleration of discarded uncontributed nodes is used to further improve lighting rendering efficiency. Finally, the cone wave filter is improved based on the multi-level texture and the adaptive combination of closed body nodes to achieve efficient calculation of global illumination. The experimental results show that, the improved algorithm reduces the amount of lighting calculations, reduces the system memory footprint, and achieves a scene lighting rendering effect similar to the classic algorithm, thereby verifying its effectiveness in large-scale lighting calculations.

BDS single-frequency pseudo-range single point positioning augmented by LEO satellites

SHAO Yinxing, ZHAO Chunmei

2020, 0(3):  69-72.  doi:10.13474/j.cnki.11-2246.2020.0080

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Single-frequency positioning is widely used because of its cost advantages, but it cannot meet the higher accuracy requirements. The effect of enhancing single-frequency positioning accuracy of LEO satellites is explored in this paper. The observation data of BDS and Iridium satellite system are simulated based on the satellite toolkit software, and the joint positioning algorithm of high and low orbit satellites is realized by combining error modeling. The results of observation stations in different latitudes are analyzed, and the results show that when the LEO ratio increases from 5% to 18%, the positioning accuracy improvement ratio increases from 48% to 80%, showing a certain positive correlation; the standard deviation of error decreases more than 50% in U direction, and fluctuates about 10% in E and U direction, showing a general improvement trend. Therefore, the addition of LEO satellites can effectively improve the accuracy of pseudo-range single-point positioning.

Distributed performance evaluation and autonomous time synchronization of navigation constellation

XIN Jie, GUO Rui, LI Xiaojie, WANG Dongxia, ZHANG Zhixue

2020, 0(3):  73-77.  doi:10.13474/j.cnki.11-2246.2020.0081

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As to the autonomous navigation requirements, the paper analyzes the availability of the autonomous time synchronization with relative clock error and on-board atomic clock, verified the coherence between the on-board atomic clock characteristic and autonomous filtering clock result, and estimated the clock prediction peculiarity within/without time reference and inter-satellite message. The results demonstrate that the clock error prediction result will be not available and increase with onboard clock characteristic and filtering parameters when the reference time of ground or other satellite and inter-satellite message are missed, and has fast convergence ability as the satellite receives the time reference information; other satellites can autonomously adjust with some satellite or anchor station as clock reference; when inter-satellite message can be satisfied, the constellation clock error has integrate draft; as to the designed algorithm, the integrate draft can reach 60 m; autonomous time synchronization error based on the onboard absolute clock error is rather stable which does not increase with time, and the relative clock error RMS is 0.6 m.

A new method for short-time prediction of BDS clock difference

CHAI Weijie, HANG Fen, LIU Guoguang

2020, 0(3):  78-82.  doi:10.13474/j.cnki.11-2246.2020.0082

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In order to improve the positioning and timing accuracy of BDS, it is necessary to calculate the satellite clock difference accurately. Considering the influence of random part error in clock difference of BDS, the prediction model of clock difference is established by fitting estimation. The model is solved by two-step minimization method based on fitting estimation. In solving covariance function coefficients, the polynomial fitting coefficients are fitted by model residual. Finally, the results of the model are compared with those of the grey theory model and the normal method of fitting and estimating. The experimental results show that the model is effective and applicable in the short-term prediction and interpolation of the clock difference of BDS.

Accuracy analysis of short baseline calculation for GPS and BDS2, BDS3 fusion data

JIN Jianjian, GAO Chengfa, ZHANG Ruicheng, WANG Bo

2020, 0(3):  83-86,95.  doi:10.13474/j.cnki.11-2246.2020.0083

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On December 27, 2018, BeiDou satellite navigation system officially provided navigation and positioning services to users around the world. The short-baseline solution experiments under different system satellite combinations are carried outusing the self-programming software in this paper. The results show that the short-baseline (5 km) in the small-area region has a positioning accuracy of 3 mm for the BDS2+BDS3 combined positioning plane and 6 mm for the elevation direction. Compared with the single GPS positioning result, the N, E, and U directions are increased by 28.9%, 6.5% and 12.2%, respectively. Compared with the single BDS2 positioning result, the N, E, and U directions are respectively increased 34.0%, 25.1% and 39.6%. GPS, BDS 2, BDS 3 fusion data processing results N, E, U all outward deviations within 5 mm.

Method for extracting urban road regular polygon by using vehicle-mounted LiDAR point cloud data

XIE Hongquan, MEI Xueqin, CAI Dongjian, WANG Yana, LIU Fucheng

2020, 0(3):  87-90.  doi:10.13474/j.cnki.11-2246.2020.0084

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With the development of self-driving high-precision map, it is necessary to extract the road rules accurately and efficiently. This paper takes a city expressway in suzhou city as the research object, obtains the city road point cloud data by using the leica vehicle-borne laser mobile measurement system, observes and understands all kinds of attribute information of the vehicle-borne point cloud data. According to the observation results, the point cloud data height difference, the point cloud gray level difference and the point cloud intensity difference are combined. Finally, the accuracy of the extracted vectorization results is evaluated. The experimental results show that: This method can get good results in extracting regular polygons and can meet the demand of high precision maps.

Method for rural road verification and its application based on Chinese high resolution remote sensing image

CAI Hongyue, YUAN Shenggu, YANG Ke, WANG Fang, SHENG Guangxiao

2020, 0(3):  91-95.  doi:10.13474/j.cnki.11-2246.2020.0085

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Traditional rural road verification requires manual field spot checks or information collection by GNSS equipment, which has the problems of high cost and low efficiency. Remote sensing images have the advantages of wide imaging range, high timeliness, low cost and can reflect the reality objectively. Compared with traditional methods, introducing remote sensing technology images into rural road verification can complete rural roads verification more objectively, accurately and efficiently. Based on high-resolution remote sensing imagery, combining with rural road remote sensing verification requirements, this paper designs and implements a rural road verification method by using remote sensing image road extraction algorithm. This method has been applied to the rural road verification work based on remote sensing images in some provinces in central China, and the practical application has proved that it can effectively improve the efficiency of remote sensing verification of rural roads.

Consideration and practice of service for natural resource management using surveying mapping and geoinformation technology in Shaanxi province in the new era

YANG Hongshan, YAN Zhenglong, ZHANG Xueping

2020, 0(3):  96-100,122.  doi:10.13474/j.cnki.11-2246.2020.0086

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Aiming at government institutions reform and the assignment of MNR, the author objectively analyzes the situation and problems of natural resources management in China in the new era. Based on technology advantages and focusing on the responsibility, Shaanxi Administration of Surveying Mapping and Geoinformation carries out analysis and preliminary practice of serving natural resource management from different fields, such as surveying and mapping reference system, standard framework analysis and construction, integration of spatio-temporal big data resources, architecture design and verification, government decision-making serving and so on. Meanwhile, SHASG verifies the stability and rationality hybrid storage environment and cloud platform architecture by using massive data processing like DEM/DOM/DSM producing covering nearly 2.8 million km², GNSS data calculation of more than 2100 national reference station network etc., which greatly improve the production and storage efficiency, provide the references for the outposts and industrial units to implement similar projects and give full play to the technology and data advantages of SHASG to better supporting for accurate performance of duties.

Application of new 3D GIS technology in natural resources and real estate information management

SONG Guanfu, LI Shaohua, YAN Yuna, XIE Minghui, TONG Yezhen, LI Kun

2020, 0(3):  101-104,117.  doi:10.13474/j.cnki.11-2246.2020.0087

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In order to realize the integrated management of natural resources and real estate such as mountain, water, forest, field, lake and grass, ministry of natural resources must consider the elements of natural ecology as a whole, which above and below the mountain, on the surface and underground, on land, in the sea, and upstream and downstream of a river basin land, to realize the integration and connection of various natural resources and real estate registration data in the whole national space. However, traditional 2D information technology has inevitable shortcomings in the expression of total factor information, the topological expression of multiple resources and the supervision and analysis of resources. To make up for the shortage of 2D GIS, new 3D GIS technology gradually formed, including data model that can express natural resources and real estate objects in full space, multi-scale, multi-source and heterogeneous 3D data fusion technology, and 3D spatial analysis and calculation technology, and realize the comprehensive management of natural resources and real estate information. On the basis of the new 3D GIS technology, the information management platform of natural resources and real estate is established to recognize the life community of mountains, rivers, forests, fields, lakes and grasses from a new perspective, improve the service capacity of natural resources and real estate management system, and realize the integrated management, use control and decision-making ability of natural resources and real estate information.

A review of 3D modeling methods for different route planning of multi-rotor single-lens UAVs

WANG Yunchuan, DUAN Ping, LI Jia, YAO Yongxiang, CHENG Libo

2020, 0(3):  105-108.  doi:10.13474/j.cnki.11-2246.2020.0088

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The multi-rotor single-lens UAV as the aerial photography equipment is taken to plan three route for the same building, such as “cross-route”, “full route” and “5 times simulation routes”. The UAV operation efficiency, model integrity and ground control point accuracy are reviewed. The experimental results show that: ① The control point has high precision based on the “cross-route”, but the model integrity is poor; ② The precision of control points based on the “full-route” is high, and the model integrity is high; ③ The control point has a slightly lower precision based on “5 times simulation routes” and the model has the best integrity.

Reconstructing building model by using 3D laser point cloud

ZHOU Yigang

2020, 0(3):  109-112.  doi:10.13474/j.cnki.11-2246.2020.0089

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With the improvement of data acquisition ability of 3D laser point cloud, building model reconstruction and elevation mapping based on 3D laser point cloud has become a common practice in engineering applications. 3D laser point cloud data can reflect abundant and intuitive details of buildings. However, the processing of massive 3D point cloud data brings great challenges to building models. The contour points of buildings are extracted by cross-cutting the 3D laser point cloud data of buildings. The TSP algorithm base on genetic algorithm are used to process the contour points and obtain the equation coefficients of the facades of buildings. Finally, the construction of building models and the detailed vector data of the facades of buildings can be obtained. The experimental results show that this method can better realize the construction of LOD1 building model, providing a basis for building model construction of higher (LOD3) level.

Construction of a model driven spatial database quality inspection platform

YE Aidong, CHEN Jinlin, ZHANG He

2020, 0(3):  113-117.  doi:10.13474/j.cnki.11-2246.2020.0090

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Quality inspection is a key point in quality control of spatial database. The spatial database consists of vector spatial data, thematic attribute data, metadata and so on. A complete inspection of a spatial database includes multiple requirements. However, existing spatial database quality inspection software are often tailored for one certain project,lacking of flexibility. Starting from the quality characteristics and its semantic expression of spatial databases, this paper analyses and studies the quality inspection rules of spatial databases, puts forward a DRST model for quality inspection of spatial databases, and develops a platform software based on this model, which can meet the needs of quality inspection of various spatial databases. The platform has been applied in the quality inspection of Jiangxi province’s real estate registration database, the third land survey and the geographical national condition monitoring results. The application practice indicates that the platform has good adaptability and expansibility, which provides an effective way to improve the efficiency of spatial database quality inspection and solves the problems of short life cycle of quality inspection software.

A case study of how to measure surface deformation using Sentinel-1A data

LI Dong, HOU Xiyong

2020, 0(3):  118-122.  doi:10.13474/j.cnki.11-2246.2020.0091

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Radar satellites combined with InSAR technology have been widely used in the field of high-precision surface deformation monitoring. In this paper, Sentinel-1A single look complex images, before and after the Jiuzhaigou M_s7.0 earthquake are chosen to derive the seismic deformation field using the D-InSAR method. The results show that the northwest side of the epicenter displays a relatively uniform subsidence. In the subsidence funnel area, the maximum settlement is 25.1 cm in the line of sight direction. While in the southeast side of the epicenter, the broken surface shows an uneven uplift, and the maximum lifting amount is 11.6 cm. The research shows that based on Sentinel-1A data, the D-InSAR technology can provide a fast and effective means for the quantitative analysis of seismic deformation field. It can provide necessary information for explaining the earthquake mechanism and assessing the disaster situation. There would be broad application prospects in the field of surface deformation survey in the future.

An improved APAP image matching algorithm

ZHANG Dongmei, LU Xiaoping, MIAO Peiji, ZHOU Yushi, MA Liangting

2020, 0(3):  123-128.  doi:10.13474/j.cnki.11-2246.2020.0092

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Aiming at the problems of image ghosting, perspective distortion and long time consumption when UAV image matching, this paper proposes an improved APAP algorithm. First, this algorithm uses SIFT algorithm to select feature points and removes the mismatch point by improving RANSAC algorithm. Then, according to the APAP algorithm, the image is meshed, the homography matrix of each mesh is obtained, and the homography matrix is linearized. Finally, the image matching is performed according to the linearized homography matrix, and the homography matrix is Linearization not only weakens the ghosting phenomenon caused by image matching, but also reduces the perspective distortion of non-overlapping regions. The experimental results show that the proposed method is effective in matching efficiency and matching effect.

A method for land supervision remote sensing monitoring based on cloud integration

SUN Jiuhu

2020, 0(3):  129-133.  doi:10.13474/j.cnki.11-2246.2020.0093

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Aiming at the problems of low monitoring frequency and poor data currency in current remote sensing monitoring, this paper researches a method of spatial grid organization and scheduling for remote sensing images, and develops the cloud-integrated remote sensing monitoring service platform for land supervision. Through the pilot application in Jinan Bureau of State Land Supervision, it has been proved that the remote sensing monitoring technical method for land supervision is feasible. In addition, the functions of real-time monitoring and early warning are carried out on illegal land use, permanent basic farmland protection and boundary breakthrough in urban development. The application has achieved remarkable results.

Research on the application of three-dimensional scanning technology based on unmanned aerial vehicle

YANG Ming, SHI Xiaowei, GE Haoran

2020, 0(3):  134-139.  doi:10.13474/j.cnki.11-2246.2020.0094

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In this paper, the concept of three-dimensional laser technology, development and research background of air-to-ground integrated scanning technology are analyzed. Then the definition of air-to-ground integrated scanning technology and the characteristics of air-to-ground integrated scanning technology are summarized. Finally its application is studied. After field operation, the aerial integrated three-dimensional scanning technology based on unmanned aerial vehicle can overcome the disadvantages of traditional methods effectively, realize the high-precision three-dimensional monitoring network of air-ground-underground monitoring and complete the multi-load data acquisition platform of airborne one-vehicle-on board one-indoor, airborne one-vehicle-on board one-indoor intellectual property series products.

Real-time cycle slip detection and repair of GNSS triple-frequency observations with wavelet transform united code-phase combinations

MENG Lingdong, CHEN Junping, WANG Jiexian

2020, 0(3):  140-144.  doi:10.13474/j.cnki.11-2246.2020.0095

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Triple-frequency signals in theory can improve cycle slip detection and repair. While, the performance of cycle slip detection and repair is largely effected by the noise of pseudorange and some special cycle slip combination cannot be detected. Aiming at current problem, using wavelet transform theory to denoise pesudorange, the success rate of cycle slip correctly repaired could be improved. Reasonable strategy QR factorization has been used to get better numerical stability; More stable equations could be formed after optimize combination observations. GPS/QZSS and BDS triple-frequency data with higher and lower sampling rate have been used to validate this algorithm. We conclude that all cycle slip manually added could be detected and repaired correctly without insensitive cycle slip combinations.

Design of full-stack teaching architecture for WebGIS course

DU Mingyi, JING Changfeng, HUO Liang, LUO Dean, HUANG Ming, ZHANG Xuedong

2020, 0(3):  145-149.  doi:10.13474/j.cnki.11-2246.2020.0096

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The dual-requirements, which are the 100 percent qualification of student in the international engineering education certification and the stronger technology of enterprises, bring opportunities and challenges to the course “WebGIS” teaching. Aiming at the problem that the existing course WebGIS teaching is still based on the traditional mode, that is “teaching-learning”, this paper proposes a full-stack teaching architecture, and designs a multi-level teaching for different types of students by analyzing the characteristics of the course. The teaching resource and teaching methods with projects can meet the requirements of all students to meet the requirements of engineering education certification. The fine-grained technical teaching design based on teaching points is developed, and the full-stack technical students can be reached through the combination of technical points. The demonstration of technical teaching design and implementation is given. The novel teaching architecture provides a teaching reference for educating WebGIS technical engineers for the international engineering certification and GIS industry.

The discussion on the photogrammetry course practical teaching under the background of UAV

DUAN Ping, LI Jia, ZHOU Jingchun, WANG Jinliang

2020, 0(3):  150-153.  doi:10.13474/j.cnki.11-2246.2020.0097

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In the practical teaching of traditional photogrammetry, the images used by students are generally collected by large airplanes. Limited by the collection equipment, it is difficult for students to directly understand such collection equipment, which ultimately leads to the lack of practical operation and understanding of the whole process of data collection. In recent years, with the vigorous development of unmanned aerial vehicle (UAV), more and more universities have UAV equipment, which makes students have more data sources in the practice of photogrammetry. Taking the photogrammetry courses of surveying and mapping engineering and geographic information science of Yunnan Normal University as teaching tasks, this paper discusses the practical links of photogrammetry teaching under the background of UAV, and provides reference for the practical teaching of photogrammetry course with UAV hardware equipment.

Teaching reform of “specialized English for surveying and mapping engineering”

LI Wei, MING Zutao, ZHANG Shaocheng, WANG Guangxing

2020, 0(3):  154-156.  doi:10.13474/j.cnki.11-2246.2020.0098

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Specialized English is a cross-disciplinary course that closely combines professional technology with English knowledge after the continuation of public English courses in higher education.This course aims to increase students’ specialized vocabulary and reading capacity, improve their reading and listening ability of specialized papers or materials, strengthen their English expression ability of specialized knowledge, and lay a foundation for students’ further study or employment. Based on teaching practice, this paper summarizes the problems existing in the current Specialized English for surveying and Mapping Engineeringcourse, such as obsolete teaching content, lagging teaching materials, single teaching method and so on. A series of concrete reform methods are proposed, such as updating teaching content, setting up diversified teaching links, making full use of new media. These strategies are applied in teaching practice to improve teaching effect and teaching quality.

Application of 3D laser scanner in tunnel construction discussion

MA Zijun, QIAO Shengyou, WEN Daorong

2020, 0(3):  157-159.  doi:10.13474/j.cnki.11-2246.2020.0099

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In order to improve the technical level of modernizing tunnel construction and realize the modeling and visualization of the construction scenes of tunnel excavation, support and lining, the 3D laser scanner is used to collect, cut, denoise and resample the tunnel 3D laser-point cloud data such that the harvested data are to be applied into all aspects of tunnel construction. Thus, an accurate and reliable basis has been provided for optimizing the drilling and blasting scheme, adjusting the reserved deformation, optimizing the initial concrete blending ratio, and eliminating the unqualified thickness of the second lining. Meanwhile, new technical means have also been supplied for tunnel engineering quantity and cost control, construction quality and deformation detection.

Extraction method of single tree skeleton points based on SX10 point cloud

LIN Zhidong, HE Yuanrong, ZHUANG Yinguo

2020, 0(3):  160-162.  doi:10.13474/j.cnki.11-2246.2020.0100

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Skeleton point is the basis of geometric model reconstruction of single tree. This paper combines three methods of level set, clustering and graph theory to extract skeleton points of single tree by using LIMSVP and Trimble SX10 to obtain point cloud data of simulated and measured single tree, and realize the skeleton point extraction of single tree. The simulation data is used for method implementation and the measured data is used for verification. In order to solve the problem of missing point cloud of single tree, three methods of level set, clustering and graph theory are reused to obtain more complete skeleton point of single tree. The results show that the method of extracting skeleton points of single tree is feasible.

Research on rebound deformation using PS-InSAR technology in loess plateau area

LIANG Xiaolong, WANG Jianye, BAI Zechao, QI Erheng, LI Pan

2020, 0(3):  163-166.  doi:10.13474/j.cnki.11-2246.2020.0101

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This paper takes a collapsible loess large-thickness excavation foundation project in northern Shanxi as the research object, and uses PS-InSAR technology to process 16 TerraSAR-X satellite images acquired from October 2018 to November 2019. Obtained rebound deformation information for the subsidence area of collapsible loess. The characteristics of time series rebound deformation of large thickness cut-out area are summarized. The results show that due to the stress unloading of the upper soil body, there is a phenomenon of rebound deformation of the foundation soil in the excavation area. The selected high-density PS point deformation information reflects the true deformation of the study area. The rebound deformation range is consistent with the excavation boundary. The greater thickness of the excavation, the more rebound deformation caused by the excavation of the soil. During the monitoring period of 1 year after the excavation is completed, the amount of deformation in the rebound zone changes linearly with time. At the maximum excavation thickness, the maximum rebound amount is 29.3 mm. In addition, the deformation amount monitored by PS-InSAR technology is in good agreement with the field level results, which shows that the technology has a good application effect in the rebound deformation monitoring of large thickness cut areas of loess.