Table of Content

25 February 2020, Volume 0 Issue 2

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Review of low-cost and high-precision positioning technology

LI Wanqing, FU Qixiang, LIU Beidian, LI Junzhi

2020, 0(2):  1-8.  doi:10.13474/j.cnki.11-2246.2020.0036

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With the rapid development of low-cost receivers such as smartphones, continuity, integrity and high accuracy are becoming new positioning requirements. Precise positioning is applied successfully in intelligent transportation, augmented reality, deformation monitoring, precision agriculture and other fields. However, the low-cost GNSS receivers with centimeter-level positioning technology have not been widely used. The realization of high-precision positioning on low-cost terminals is restricted by the signal processing capability, and the phase center error and the multipath error caused by its low-quality antennas. The improvement of the positioning accuracy by antenna motion also brings a new opportunity to reduce positioning cost. This paper discusses efforts to implement the application of high-precision positioning technology in low-cost receivers by means of making a summary of existing exact positioning technologies and analyzing the obstacles of cost-saving receivers and discusses the solutions of low-cost and precise positioning. Finally, the research trend of low-cost and high precision positioning in the future is prospected based on existing research.

The recent progress and expectation of research on model for urban public service facilities location optimization problems

MA Xiaoya, LIU Yuangang, ZHAO Xiang

2020, 0(2):  9-16.  doi:10.13474/j.cnki.11-2246.2020.0037

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The allocation of urban public service facilities has essential impacts on social equity and justice. Unreasonable allocation of urban public service facilities often leads to the paradoxes of shortages and excesses of urban public services, while also reducing the use of the allocation of public service facilities. In recent years, the rapid development of big data, intelligent decision-making and simulation technology has triggered a revolution in the research of urban public service facilities allocation model. Based on the above background, this paper summarizes and prospects the recent research progress of the optimal allocation model of urban public service facilities. Firstly, the optimization decision model for urban public service facilities has greatly developed with the application of the accessibility analysis methodologies and the concept of equalization of public services. Secondly, the spatial-temporal simulation and prediction of urban public service demand is becoming more and more accurate. The application of big data and spatial-temporal data mining in urban public facilities allocation makes it possible to simulate the demand of public services on more elaborate spatial and temporal scales. Thirdly, the multi-objective intelligent optimization decision-making method promotes the intellectualization of decision-making in urban planning. It is foreseeable that with the wide application and integration of new technologies such as big data, cloud computing, parallel computing and artificial intelligence in the field of GIS, the optimal allocation model of urban public service facilities will be more and more refined and intelligent.

A perceptual Hash target tracking algorithm based on dynamic prediction

CHEN Youliang, XIAO Gang, BIAN Huan, HU Min

2020, 0(2):  17-23.  doi:10.13474/j.cnki.11-2246.2020.0038

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In order to achieve target tracking in static background, a DTC-based perceptual Hash generation algorithm is used to extract the target-aware Hash summary, and the Hamming distance is compared to achieve template matching. Aiming at the problem of insufficient tracking efficiency, a range and azimuth fusion prediction strategy is proposed, in which the range predicts the range of the predicted target and narrows the template search area. The azimuth prediction finds a faster and shorter search route based on the range prediction. The tracked coordinate elements are simplified into a single azimuth feature, the four prediction models are used to predict the target orientation, a template matching termination condition is mined, the window traversal is stopped at an appropriate depth. The experimental results show that the range prediction improves the tracking efficiency significantly. When the prediction range is reduced by n times, the algorithm efficiency is improved by about n² times, and the azimuth prediction can improve the efficiency by about 16% based on the range prediction.

A method of deep convolutional neural network photo classification for landuse scenes

XU Shiwu, ZENG Jue, ZHANG Shihui, LI Changzheng, LI Tingyu

2020, 0(2):  24-28,42.  doi:10.13474/j.cnki.11-2246.2020.0039

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The multi-angle real-life proofed photos of the national land survey have multiple characteristics:high resolution, rich layers, and clear sections. The photos are accurate and detailed depictions of the occurrence status and scenes of landuse maps, which makes up for the lack of ground perspective of remote sensing images. Based on semantic segmentation, this paper proposes an innovative landuse scene classification method with a deep convolutional neural network (DCNN) for ground perspective photos. The method annotates photo scenes with multi-semantic technique and determines categories of photos of landuse with semantic composition. Successfully applied in the third automatic survey of land survey photos, this method reduces the workload of manual interpretation and improved the accuracy of automatic identification of landuse scenes.

A combined algorithm of improved LBP and HSV for surface state recognition

SUN Yishan, LI Xiaojie, ZHAO Kai

2020, 0(2):  29-36,71.  doi:10.13474/j.cnki.11-2246.2020.0040

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Different surface states will lead to different modes of electromagnetic wave propagation, which determines the different detection methods, detection wavelengths and detection methods of remote sensing, when the surface information is retrieved by near-surface remote sensing. Therefore, surface state recognition is the premise of remote sensing retrieval of near-surface, and recognition accuracy determines remote sensing retrieval accuracy. A combined algorithm of LBP(local binary pattern)and HSV color histogram for surface state recognition is proposed. Feature vector extraction is carried out by combining the Improved Threshold LBP algorithm and HSV color histogram, then discriminant condition is established, in the end, the results of recognition can be realized by feature matching between test samples and training samples, based on K-neighborhood algorithm. 411 images collected in the field are divided into training samples and test samples randomly. The correct rate of recognition for 206 test samples is more than 98.7%, It is proved that the algorithm is effective.

Scene classification of high-resolution remote sensing image combining data augmentation and transfer learning

QIAO Tingting, LI Luqun

2020, 0(2):  37-42.  doi:10.13474/j.cnki.11-2246.2020.0041

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Deep learning has achieved remarkable results in the field of computer vision, such as image classification, face recognition, image retrieval and so on. For remote sensing, obtaining a labeled dataset for training DCNN is often a major challenge. In this paper, the use of DCNN for scene classification in high-resolution remote sensing imagery is investigated. In order to overcome the lack of a large number of labeled remote sensing image datasets, two technologieswere combined with DCNN:data augmentation and transfer learning. On the UC Merced Land Use dataset, the performances of 5 networks including VGG16, VGG19, ResNet50, InceptionV3, and DenseNet121 were verified, which achieved classification accuracy of 98.10%, 96.19%, 99.05%, 97.62%, and 99.52%, respectively.

Gross error detection and application of ground-based SAR in complex environment

MA Jinyu, LONG Sichun, TONG Aixia, WU Wenhao, ZHU Chuanguang

2020, 0(2):  43-48,54.  doi:10.13474/j.cnki.11-2246.2020.0042

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The intermittent occlusion of radar line of sight by construction machinery leads to the phase singular value of some images, resulting in unwrapping errors and error transmission, and it is difficult to identify the occluded images by simple related image processing. This paper proposes an improved method of signal singularity detection based on wavelet transform. Through the analysis of the temporal phase characteristics of the ground-based SAR PS points, the occlusion image recognition is transformed into the problem of gross error detection. According to the relationship between the PS point phase sequence and the image position, the occluded image set is obtained according to the singular point set of the PS point phase sequence in the survey area. Finally, the ground-based SAR monitoring results obtained by removing the occluded image are compared and analyzed with the precision total station, level and vernier caliper data. The results show that the method proposed in this paper is feasible for the recognition of occluded images. It solves the problem of gross error in the measurement data caused by the possible image occlusions in the practical engineering application of ground-based SAR, and improves the efficiency and accuracy of the detection of false images in the monitoring area.

Extraction method of intertidal mangrove by using Sentinel-2 images

XU Fang, ZHANG Ying, ZHAI Liang, LIU Jia, GU Xianghui

2020, 0(2):  49-54.  doi:10.13474/j.cnki.11-2246.2020.0043

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Mangroves located in intertidal zone may be submerged by sea water at high tide, which makes the traditional vegetation extraction methods are limited at mangrove information extraction. After comparing and analyzing the spectral characteristics of mangroves exposed, mangroves submerged at high tide level and seawater bodies, a method of extracting intertidal Mangroves by using normalized intertidal mangrove index (NIMI) is proposed in this paper. The index is normalized expressions for the composition of a red band strongly absorbed by vegetation and two red-edge bands as well as a near-infrared band strongly reflected by vegetation. The index is used to classify and extract mangroves from Jiulongjiang Estuary wetland in Longhai, Fujian Province. The results are compared with the results of visual verification of GF-2 and field investigation. The results shows that the user accuracy of this method reaches 93.98%, and is significantly better than that of using normalized water index (NDWI), normalized vegetation index (NDVI) and the results of random forest.

The method of 3D reconstruction of farmland terrain environment based on LiDAR

LANG Lang, FENG Xiaorong, LIU Lang

2020, 0(2):  55-60.  doi:10.13474/j.cnki.11-2246.2020.0044

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In order to overcome the time-consuming and laborious characteristics of traditional land leveling measurement methods, LiDAR technology is proposed to reconstruct farmland terrain. The hardware platform of the system is built by HDL-32E LiDAR, and the data acquisition program is compiled by C++ language. On this basis, the data collected by the LiDAR is calibrated, and the transformation methods of different coordinate systems in the farmland terrain reconstruction system are studied. Meanwhile, based on the minimum denoising method, a denoising method with mean difference is designed, which is more suitable for the denoising of farmland terrain point clouds. This is the case. The system accuracy is evaluated by comparing the number of units measured by RTK and LiDAR in the region with large fluctuation of farmland and without slope. Finally, the interface display, application and accuracy evaluation of the vehicle-mounted farmland terrain reconstruction system are realized. The results show that the farmland topography obtained by LiDAR is more abundant and accurate in the range of of 10°~15°、25°~30°. The projection area approximation of the reconstructed farmland topographic model point cloud data and the original farmland topographic point cloud data can reach 93%. It shows that the research method in this paper can be applied to the reconstruction of farmland topographic environment. At the same time, it provides a theoretical reference and basis for the future work of land fine leveling.

Loose coupling filtering algorithm for mobile phone vision and inertial fusion

LIU Xing, GUO Hang

2020, 0(2):  61-65.  doi:10.13474/j.cnki.11-2246.2020.0045

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With the popularity of smart phones and the Internet, the demand for high-precision positioning technology is also more significant, and the accurate positioning services have penetrated into various fields, such as the Internet of things, driverless, machine couriers, emergency rescue and so on. In outdoor environment, most of these services are provided by the global satellite navigation system. However, in indoor environment, such as deep mountain jungle, mine tunnel, basement and so on, GPS can not work properly due to signal attenuation and the influence of multi-path effect. Aiming at some special indoor scenes, this paper studies the visual inertial fusion navigation method based on loose coupling filter, and designs an indoor pedestrian positioning system for smartphone platform. In this method, the fast and robust sparse direct method is used in the visual front end, and the extended Kalman filter is used in the back end to fuse the inertia information. It can effectively integrate visual and inertial information, restore monocular visual scale, improve robustness, and achieve high precision indoor pedestrian location.

Data generation method of constellation heterogeneous base station virtual reference station

ZHANG Xi, CHEN Xianchun, BAO Hai

2020, 0(2):  66-71.  doi:10.13474/j.cnki.11-2246.2020.0046

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Traditional virtual reference station service is always exist constellation blind areas as constellation compatibility difference among reference stations. In order to overcome this disadvantage, a method is proposed to calculate virtual observation on the basis of error source analysis. Firstly, network construction is built through each GNSS constellation. Secondly, the master reference station of each GNSS constellation is searched. Thirdly, the master reference stations' receiver clock error are calculated and repaired. Finally, observations of multiple master reference stations are used to calculate observations of one virtual reference station. It effectively avoids the influence of single master reference station's constellation compatibility, and provides more satellites' differential data for rover station. In view of the incompatibility of some reference stations with BeiDou satellites, five reference stations are chosen to construct the observational network, and the middle station's BeiDou data is closed. Three test schemes are developed and rover station's positioning performance is tested in open areas and corner areas respectively. The experiment results confirm that virtual observation quality can be improved by combining more reference stations. Rover station can get better positioning quality, especially the usability and positioning quality can be significantly improved in the corner areas. The research has practical applicable value for combining existing reference stations and improving constellation compatibility of network RTK service.

Typhoon similarity evaluation algorithm considering spatiotemporal trajectory features

ZHANG Keke, LUO Nianxue, ZHAO Qiansheng, ZOU Zixin

2020, 0(2):  72-76.  doi:10.13474/j.cnki.11-2246.2020.0047

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Similar typhoon tracks reflect to some extent that influencing factors have the same or similar comprehensive impacts on typhoon movements. In this paper, considering the trajectory space-time distance and frequency characteristics, distance-frequency algorithm, a spatio-temporal trajectory similarity measurement algorithm based on IMHD-ST distance is proposed. The similarity between typhoon trajectories is evaluated on two aspects of spatio-temporal position and shape. Experimental results show that the calculation results remain accurate, meanwhile the resistances to noise, sampling rate change and offset have been improved, therefore can effectively match similar trajectory pairs and applied to typhoon tracks forecast and similar typhoon cases extraction.

The construction of road tree detection network based on segment weighting

SHEN Yu, QIU Yuxuan, YU Zhenghao

2020, 0(2):  77-81,101.  doi:10.13474/j.cnki.11-2246.2020.0048

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In this paper, an end-to-end training network is proposed based on the framework of deep learning forobject detection, which can be used for automatic street treesdetection. Because of the occlusion problem between the roadway trees, the existing general object detection framework cannot be applied to this task directly. In this paper, a tree-shaped partial weighting module is proposed to reduce the error detection caused by severe occlusion. Then, the proposed neural network is trained and evaluated. The results show that the partitioned weighted tree detection network established in this paper can effectively detect the street trees in street scenes under occlusion conditions. The experimental results further show that the method gets high accuracy and good robustness under various conditions.

DOM automatic production algorithm based on point cloud filter

BAI Shihan, LIU Bin, BAI Shaoyun, GU Shixiang, XING Kuanping

2020, 0(2):  82-85,101.  doi:10.13474/j.cnki.11-2246.2020.0049

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This paper proposes a DOM automatic production method based on point cloud filtering to solve the current low-precision DOM generation efficiency and manual editing intervention.This method uses TIN-based encryption filtering to filter the dense point cloud DSM, and solves the problem of interpolation in the void area after filtering. A DEM model is made to meet the demand of differential correction. Finally, DOM results are generated by differential correction based on this model. The ISPRS urban experimental data and the actual engineering mountain data were selected for experimental analysis. This method improved the generation efficiency, optimized the quality of the results, and the accuracy of DOM results met the requirements of the specification.

Classification of GF-3 fully polarimetric SAR image combined with the Singh four-component decomposition

WANG Songsong, ZHANG Yonghong, KONG Xiangyi

2020, 0(2):  86-89.  doi:10.13474/j.cnki.11-2246.2020.0050

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Different from general classification algorithm, pixel statistics based classification ignores the scattering characteristics of objects. In this paper, an classification method for preserving the scattering characteristics of objects was proposed. This method combined the Singh four-component decomposition proposed by Singh with the maximum likelihood classifier based on the complex Wishart distribution for classification of GF-3 polarimetric images. Surface scattering, volume scattering, double-bounce scattering and helix scattering were obtained by Singh four-component decomposition, then the first three basic scatterings were divided into multiple clusters respectively, and the inter-class merging was performed according to the complex Wishart distance until the specified number of categories was obtained. The Wishart classifier was used foriterative classification and merged the categories at last to obtain the final classification result. Through experiments, it was proved that the algorithm proposed in this paper had a good classification performance and verified the feasibility of using GF-3 satellite data for image classification.

Analysis of the Qilu Lake watershed landscape pattern based on multi-scale image data

BAI Shaoyun, LIU Bin, YU Peiheng, CHEN Min, PAN Jiawei, CHEN Yiyun

2020, 0(2):  90-95.  doi:10.13474/j.cnki.11-2246.2020.0051

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Landscape pattern is the concrete embodiment of landscape patch order and rule. Analysis of landscape pattern characteristics can promote the delimitation and management of the red line of watershed ecological protection in spatial structure. In addition, there may be differences in calculation results and inconsistent description of landscape pattern based on different remote sensing observation data sources. Taking Qilu Lake watershed as the research area, this paper uses the latest satellite remote sensing images of Entinel-2, GF-1 and Landsat 8 to calculate seven landscape indices of patch scale, type scale and landscape scale, discusses the current situation of landscape pattern in Qilu Lake watershed from two aspects including landscape type distribution and overall pattern, and analyses the similarities and differences of landscape pattern evaluation from different data sources. The results show that:① The landscape pattern of Qilu lake watershed is dominated by woodland and arable land, scattered with construction land and other lands. ② Different satellite remote sensing images have different descriptions of the landscape pattern of the watershed, and the image resolution has a significant positive correlation with Number of Patches, Largest Patch Index, Landscape Shape Index and Splitting Index and low correlation with Shannon's Diversity Index, Shannon's Evenness Index and Dominance Index.

Improvement and evaluation of building model acquisition accuracy based on oblique photography model

YU Zhiqiang, HUANG Hua, XU Chuangfu

2020, 0(2):  96-101.  doi:10.13474/j.cnki.11-2246.2020.0052

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This paper studies the acquisition of building models based on inclined photography and the optimization algorithm to improve the accuracy. The existing building model acquisition methods cannot achieve good precision control, the building edge acquisition method is single, the acquired edge is not processed by algorithm. In view of this reason, a method of building edge line acquisition with constraint conditions is proposed and the algorithm research of building edge line precision is calculated based on the relationship between building edge line and wall. That is, with the given collection method and optimization algorithm, the acquisition method is firstly used to obtain the thick elevation line map of the building, and then these data are unified and optimized in batches. The optimization algorithm of acquisition method can effectively improve the accuracy of elevation line data from the acquisition stage and optimization stage respectively.

UAV tilt photogrammetry earthwork calculation and accuracy evaluation

LI Bo, XU Jinghai

2020, 0(2):  102-106,112.  doi:10.13474/j.cnki.11-2246.2020.0053

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With the development of the tilt photography technology of the unmanned aerial vehicle (UAV), it provides a solution to the some difficult work in earthwork measurement, such as terrain limitation, time-consuming and labor-intensive. In this paper, a method of earthwork calculation is described with UAV tilt photography supporting by PhotoScan software. The classification method of point cloud and the value correction method of non-ground point elevation are introduced. By analyzing the ground control points, point cloud classification methods and non-ground point elevations, this paper proposes three principles for optimizing non-ground point layout. The accuracy of the earthwork calculation of tilt photography is verified with the real-time kinematic (RTK) GPS method. The result shows that the use of UAV tilt photography technology in earthwork calculation can not only simplify the on-field and in-door survey work, but also save cost. The accuracy of earthwork calculation can be improved through properly setting ground control points, improving point cloud classification, correct non-ground point elevation.

Urban underground rail transit settlement and disaster monitoring based on InSAR

QIU Yahui, BIE Weiping, BO Zhiyi, LI Changqing, ZHENG Kuo, LANG Bo

2020, 0(2):  107-112.  doi:10.13474/j.cnki.11-2246.2020.0054

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The construction of urban metro will cause damage to the geological environment in the neighborhood, even catastrophe. The traditional methods based on point measurement have some shortcomings in practical application, such as long field operation cycle, weather influence and consuming a lot of manpower and resources. Therefore, based on the application requirements of urban underground train safety construction, taking Tianjin metro Line 5 as an example, this paper uses 27 TerraSAR data and PS-InSAR time series method to monitor and evaluate the impact of underground train construction. The results show that PS-InSAR can monitor the deformation of metro line and its surrounding areas during construction period, which is beneficial to the whole life and health monitoring of urban rail transit.

CPⅢ survey technology and data processing of railway connecting line

CHEN Jun

2020, 0(2):  113-117.  doi:10.13474/j.cnki.11-2246.2020.0055

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The connecting line is quite different from the main line in detour mode, single and double lines, track structure, design speed and design height, and the maintenance and inspection during the operation period require the whole line CPⅢ to be measured and laid out. The connecting line has no available pole and column structures for CPⅢ layout due to single line detour, and the CPⅢ survey is difficult to see due to terrain elevation difference. Through on-site investigation and data comparison and analysis of many railways such as Nanjing-Qidong Railway and Nanjing-Hangzhou Railway, the research conclusions are put forward:First, the types of CPⅢ layout using existing pole and column structures are enriched; The second is to develop non-mandatory centering CPⅢ logo; Thirdly, the method of co-point network distribution in the connection section is studied. Among them, 4 national patents have been obtained for non-mandatory centering CPⅢ marks. The co-point network distribution method for connecting sections reduces the burying workload and joint measurement workload, thus greatly improving the work efficiency. A novel concept such as "CPⅢ co-point is adopted for encrypted CPⅡ, and CPⅡ co-point is adopted for encrypted level" is put forward, which can provide basic data for GNSS elevation measurement and elevation anomaly research.

Research on public representation method of animation effect map

ZHOU Xinwei, DI Lin, BAI Jinghui, LIU Jie, LIU Xiaohui

2020, 0(2):  118-120.  doi:10.13474/j.cnki.11-2246.2020.0056

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The representation of public map is related to national security, territorial integrity and national dignity, which has serious political nature, rigorous scientific and strict legality. Animation effect map is a popular and effective carrier of information dissemination, but there are blind areas in public representation, and it is a high incidence area of problem map which may cause serious impact. This paper summarizes the characteristics, common problems and causes of animation effect map, puts forward suggestions for animation effect map representation method, clarifies that both base map and animation effect should meet the requirements of public map representation method. That has certain guidance and inspiration for the production and public use of animation effect map.

Study on monitoring rocky desertification based on the combination of remote sensing interpretation and geographical conditions

LI Wei, WEI Man

2020, 0(2):  121-125.  doi:10.13474/j.cnki.11-2246.2020.0057

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Considering the complexity of the surface rocky desertification, drawing on the evaluation methods of the state and degree of the rocky desertification of the forestry department, making full use of the results of the geographical conditions of the land surface coverage and DEM, combining with the remote sensing monitoring technology to calculate the comprehensive coverage of the bedrock and vegetation on the surface, taking the field investigation as the evidence, obtaining the monitoring and evaluation factors of the rocky desertification in the study area, and determining the state and degree of the rocky desertification in the study area, a set of rock desertification monitoring technology is constructed based on remote sensing interpretation. The results show that from 2008 to 2016, the occurrence rate of rocky desertification in the study area has decreased significantly, and the regional ecological environment has been gradually restored. The technical methods of this study are feasible, and on the basis of saving human resources, the status and degree of rocky desertification can be quickly obtained.

Calibration of placement angle deviation for shipborne mobile LiDAR 3D surveying system

SHEN Wei, SHUAI Chenfu, HUI Xiao, LUAN Kuifeng, ZHANG Huachen, MA Jianguo

2020, 0(2):  126-130.  doi:10.13474/j.cnki.11-2246.2020.0058

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The shipborne mobile LiDAR 3D surveying system is a multi-sensor integrated system integrating laser scanner, global positioning system and inertial navigation system. It has the characteristics of high efficiency, high precision and 3D surveying, and it can solve the problem that traditional methods are difficult in the mapping of docks, river courses and islands and reefs. The high-precision space-time synchronization of the LiDAR surveying system is the guarantee of data fusion and high-precision 3D surveying. The placement angle deviation calibration is an important step in the surveying of system. This paper first analyzes the conversion relationship in the relevant coordinate systems in the shipborne mobile LiDAR 3D surveying system, and proposes a method to eliminate deviation based on the bridge as the calibration field. Based on the high-precision space-time synchronization, the method calculates the placement angle deviation of the roll angle, the pitch angle and the heading angle respectively by the offset of the bridge in the scanning line. Finally the reference points are used to verify the surveying accuracy after calibration. The experiment verifies the accuracy of the method and it can significantly improve the quality and accuracy of shipborne mobile LiDAR surveying data.

Knowledge mapping analysis and outlooks of the digital ocean research

BAI Tingying, YANG Renfei, HUI Datao, HE Wenwen, ZHANG Yanguang, HE Jing

2020, 0(2):  131-136.  doi:10.13474/j.cnki.11-2246.2020.0059

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It has been 20 years since the concept of digital ocean was put forward. Based on the key words of "digital ocean", the digital ocean research literature published from 1999 to 2018 in China National Knowledge Infrastructure (CNKI) Databaseis, searched the development process, subject participation, research quality and evolution characteristics of digital ocean research in the past 20 years using the knowledge mapping methods are summarized. The results show that the achievements of digital ocean research rapid grew in the past two decades, and the level of attention has gradually increased. The participating disciplines are centered on oceanography and cover many disciplines, the types of literature are comprehensive, but the quality still needs to be improved. The research topics are obvious, that is to follow the wave of information technology closely. After experiencing the rapid development stage, the current digital ocean research has entered a relatively stable stage, but there is still space and necessity to explore in the research content, methods and technology. It is analyzed that in the future, the research of digital ocean should be developed in the direction of globalization, application, refinement and intelligence, so as to enter a new research climax.

Life convenience analysis of Lanzhou residential area based on the colorimetric co-location rule excavation

LIU Tao, ZHANG Xiaohui, HU Tian, LIU Yongqiang

2020, 0(2):  137-141,146.  doi:10.13474/j.cnki.11-2246.2020.0060

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Analysis of living convenience in residential areas is a hot urban research issue. People's activity in urban area mainly occurs in road network space. Additive color method based co-location pattern mining is a concise and effective visual data mining method in network space. This paper uses the visual data mining method to analyze residential life convenience. Taking Lanzhou city as an example, the experiment is carried out to mine the spatial co-location pattern between residential area and other 14 city infrastructures' location. On the basis of co-location pattern mining results, the residential life convenience was analyzed and evaluated. The results show that the residential areas in Lanzhou city have the best co-location pattern with pharmacies, supermarkets, Lamian noodle restaurants, have good co-location pattern with hospitals and hotpot restaurants, and have poor co-location pattern with shopping malls, police stations and fire stations. Residential areas present a distribution characteristics of "multiple livable centers" in Lanzhou city,and livable center in eastern area have a higher convenience than western area.

DEM generation in difficult areas based on InSAR and weighted fusion

HU Dongming, SUI Lichun, DING Mingtao

2020, 0(2):  142-146.  doi:10.13474/j.cnki.11-2246.2020.0061

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Synthetic aperture radar interferometry (InSAR) technology has the characteristics of all-day and all-weather, and it can extract DEM quickly and efficiently in a wide range. DEM can be generated normally by InSAR technology even in rainforests covered by cloud and fog all year round. In the second chapter, DEM in the research area is generated by InSAR, which verifies the feasibility of this method. Due to dense vegetation in the study area and a large area of water swamp, low coherence and partial incoherence phenomena exist in the InSAR processing process, which easily leads to errors and cavities in DEM generated based on InSAR technology. To solve this problem, a pixel-level fusion method based on coherent basis as a weighted function is proposed in this paper, where SRTM DEM and AW3D30 DEM are used as exogenous data to fuse with InSAR DEM. In this way,the problems of errors and cavities in DEM generation based on InSAR technology can be solved, and the integrity of DEM can be guaranteed.

The cognition and representation of spatio-temporal behaviors of wetland based on spatio-temporal objects of multi-granularity

CHEN Yunhai, JIANG Nan, ZI Lu

2020, 0(2):  147-150.  doi:10.13474/j.cnki.11-2246.2020.0062

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Wetland, as a kind of living spatial entity, has complex spatio-temporal behaviors. The cognition and presentation of its behaviors have always been the focus and difficulty in this field. The pan-spatial information system could abstract and describe the real world directly based on spatio-temporal objects of multi-granularity, which is more convenient than traditional GIS for people's cognitive habits. Therefore, this paper, using the method of spatio-temporal objects of multi-granularity modeling, initially explores the cognition and presentation of its spatio-temporal behaviors by analyzing and summarizing the wetland data organization method, spatio-temporal behavioral cognition, classification, representation respectively. It turns out that wetland's spatio-temporal behaviors could be classified by the granularity, number, characteristic attributes of wetland respectively. And the representation of behaviors could be progressed by three levels, including dynamic display, analytical modeling and model prediction. Furthermore, this method, compared with the previous representation methods, has many advantages, such as dynamic, correlation and real-time. Finally, it could provide a new method for the dynamic monitoring of wetland resources.

Application of TLS in acquisition of complex steel structure features

GAO Zicheng, WANG Guoli, GUO Ming, ZHOU Tengfei

2020, 0(2):  151-154,159.  doi:10.13474/j.cnki.11-2246.2020.0063

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With the rapid development of the construction industry, a large number of complex steel structures have been built all over the country. The structure is complex and the building volume is huge. In the process of steel structure construction, in order to accurately splicing the steel structure or facilitating the installation of other components. It is often necessary to obtain characteristic information on steel structural components. It is difficult to obtain the characteristic information for the installation and inspection of traditional steel structures, and delay the construction period. The 3D laser scanning can quickly acquire the point cloud data of the steel structure through a large-scale intensive scanning, and the processing can obtain the characteristic information of the steel structure. Taking the coordinate acquisition of large steel structure disc members of Zhoukoudian Peking Man Site as an example, this paper introduces the acquisition and data processing flow of steel structure point cloud data and the method of component node coordinate extraction based on geometric position relationship. The results show that the 3D laser scanning technology can quickly and accurately acquire the characteristics of steel structural members under the engineering coordinate system which can meet the engineering precision requirements.

Analysis and treatment of pollution sources using BDS and unmanned ships

JIANG Fengshan, YUE Zhongyang, CEHNG Junying, ZHAO Zeyang

2020, 0(2):  155-159.  doi:10.13474/j.cnki.11-2246.2020.0064

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This article make full use of the position function of BeiDou Satelites Navigat System under the background of large data. The positioning function, using unmanned ships as the client, actively explores new practice solutions in the issue of water quality data collection and source location, and quickly and accurately finds the source of pollution, reduce the time of river pollution, and no one on board has the corresponding purification module, do some simple treatment when found pollution. The water quality analyzer is installed on unmanned ships, and the BeiDou satellite positioning chip, WiFi data transmitter, is waterproof processed in the transmission module of the water quality analyzer. The types and concentrations of pollutants in rivers are analyzed, and the location of pollution sources is calculated using the calculation method of large data, and the results of pollution source analysis and pollutant treatment methods are reflected in the cloud platform. Through the BeiDou Satellite Navigation System, these data are divided into locations and the shortest route to the source of pollution is sent to the processing person's mobile device. This paper analyzes the visual system of water pollution monitoring based on BeiDou satellite positioning in order to find out the pollution sources quickly and reduce the water pollution.

Point cloud and BIM model registration based on improved adaptive genetic algorithm

LI Guoyuan, WANG Jian, LIU Xiuhan, SUN Wenxiao

2020, 0(2):  160-162.  doi:10.13474/j.cnki.11-2246.2020.0065

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Registration of point cloud and design model is a key step in digital detection of steel structures.The traditional registration method is computationally intensive and slow in convergence. Aiming at accurate registration, an improved adaptive genetic algorithm is proposed for the registration method of point cloud and design model, adaptively adjust the execution order of cross probability and mutation probability and the magnitude' of probability value, and improve the diversity of population and convergence speed. Experiments show that the improved adaptive genetic algorithm greatly improves the accuracy and convergence speed of point cloud and model registration.

Application of Leica RTC360 3D laser scanner in facade reconstruction

DONG Jingli

2020, 0(2):  163-166.  doi:10.13474/j.cnki.11-2246.2020.0066

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As the latest Leica RTC360 ultra-fast 3D laser scanner, it is simple to operate and fast to scan, and it can complete the acquisition of massive and rich point clouds and high-definition images in the shortest possible time, with comprehensive data, rich details, and extremely greatly improved work efficiency in the field. It is very intelligent. Using VIS vision tracking technology, through tracking and positioning of the scanner position, it can achieve real-time stitching of the point cloud during the acquisition process, without the need for targets, public points, and manual intervention, real-time viewing of the point cloud pre-stitching in the field. It can greatly reduce the workload in the industry. In the later stage, the Cyclone Register 360 intelligent splicing software is used. The point cloud does not need manual intervention. The point cloud implements automatic intelligent splicing processing, which enables simple and efficient field collection and internal data processing.