Table of Content

25 October 2018, Volume 0 Issue 10

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Current Status of Large-scale GNSS Network Development and Data Processing

LI Linyang, ZHANG Xuedong, HUANG Xian, LI Chonghui, LÜ Zhiping

2018, 0(10):  1-5.  doi:10.13474/j.cnki.11-2246.2018.0303

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Large-scale GNSS network is a critical infrastructure to achieve high-accuracy location service.The current development status of large-scale GNSS network is analyzed from the aspect of space segment,ground segment and data quantity.Available satellites and frequencies increase significantly in the space segment,while the scale of GNSS network is bigger and bigger in the ground segment,and thus the GNSS data quantity increases exponentially.Then,the storage and management method of massive GNSS data are summarized in detail,centralized storage method cannot meet the needs of large-scale GNSS network data storage application,while cloud storage is an effective solution.Finally,the processing strategies of large GNSS network are concluded systematically,and the bottleneck of GNSS data processing is solved by improving model algorithm and using parallel computing technology.

Analysis of Satellite Differential Code Biases and Accuracy by Fusion of BDS/GPS/GLONASS

WANG Jian, DANG Yamin, WANG Hu, LIU Yangyang, REN Zhengzhao

2018, 0(10):  6-9,21.  doi:10.13474/j.cnki.11-2246.2018.0304

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Satellite differential code deviation is an important factor affecting the navigation and positioning accuracy of users. This paper combines the data of BDS/GPS/GLONASS three system and uses the software of iGMAS analysis center of China Academy of Surveying and Mapping to solve the satellite differential code deviation. Results show that GPS P1P2 satellite differential code bias and CODE products is very consistent, the accuracy is very high, and very stable. BDS B1B3 satellite differential code bias and CODE products are basically consistent and stable. GLONASS P1P2 satellite differential code bias and CODE products are relatively consistent, high precision and stable. Comparison of three systems, GPS system P1P2 differential code bias has the highest accuracy, and is the most stable. GLONASS system P1P2 differential code bias stability and accuracy is slightly lower than the GPS. BDS system B1B3 differential code bias precision and stability is the lowest, which may be a cause of incomplete constellation.

Cascade Dual Frequency Carrier Phase Smoothing Optimization Algorithm Under GBAS

YU Geng, WANG Han, ZHAO Long

2018, 0(10):  10-13,26.  doi:10.13474/j.cnki.11-2246.2018.0305

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Both temporal and spatial gradients of ionosphere are major factors that influence the phase smoothing of the carrier for GBAS.In order to reduce the effect of ionosphere on the pseudo-range smoothing output and improve the availability of the differential correction on smoothed pseudo-range,a cascaded dual-frequency smoothing filtering algorithm based on the analysis of additional ionosphere error induced by single frequency phase smoothing is proposed.The filter algorithm estimates effectively the ionosphere delay in the navigation signal through the first-order low-pass filter,and takes code minus carrier (CMC) generated through linearly combining the first-order filter output with dual-band signal pseudo-range value and the carrier phase value as a second-order low-pass filter input,with correcting the output of the smooth pseudo-range value of the clock correction,eliminates the ionosphere delay error and attenuate the received signal noise.The results show that the improved algorithm can effectively reduce the influence of the ionosphere on the pseudo-range differential correction and the residual error of the smoothed pseudo range,improve the availability of the smoothed pseudo-range differential correction,and the positioning accuracy during the precision approach landing.

An Improved Generation Algorithm for Projection Matrix in Computerized Ionospheric Tomography

YU Longfei, HU Wusheng

2018, 0(10):  14-16,21.  doi:10.13474/j.cnki.11-2246.2018.0306

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The acquisition of projection matrix is the key step in computerized ionospheric tomography based on pixel. Because of the algebraic method, the traditional method not only has a complex process, but also cannot get unique solution. The unique solution cannot be obtained by using traditional method, and it is necessary to determine which solution satisfies the condition. Aimed at this deficiency, a method of obtaining projection matrix based on vector relation is proposed by analyzing the intersection point between satellite signal ray and 3D pixel plane. The novel method reduces the number of unknowns and the complexity of the computation, and obtains the unique solution without determining. It reduces the redundancy and improves the efficiency.

Automatic Method for Extracting Cutting Line of Filler of Cultural Relics' Safety Box

SONG Yueting, ZHENG Shunyi, WANG Xiaonan, DUAN Zhixin

2018, 0(10):  17-21.  doi:10.13474/j.cnki.11-2246.2018.0307

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In the process of transport,the cultural relics need to be placed in a safety box of considerable shape to protect it from damage.At present,the cutting line of the filler of the safety box was measured and drawn manually.This was time consuming and laborious,and the cutting line didn't fit the object very well.To solve these problems,this paper presented a method to automatically determine the cutting line.Firstly,it preprocessed the image and extracted the contour using the boundary tracking method.Secondly,it established the reference relationship between image and object using homography matrix and proposed the error correction equation.Finally,it applied the quantitative scaling and curve fitting to the contours according to the actual needs.The experiments demonstrate that the proposed method can automatically and efficiently determine the cutting line,and the cutting line fits the object well.

A Method of Semi-supervised Classification for Hyperspectral Images Based on Spatial Information and Genetic Optimization

HU Dongcui, XIE Fuding, YANG Jun, ZHANG Yong

2018, 0(10):  22-26.  doi:10.13474/j.cnki.11-2246.2018.0308

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Among many dimensionality reduction methods,because of the simplicity of spectral methods,it has been widely applied in recent years.In the spectral method,the construction of graph and the selection of similarity function are the key factors affecting the dimensionality reduction effect.A semi-supervised hyperspectral image classification method is proposed based on spatial nearest neighbor information,genetic algorithm,spectral method and a small number of label sample points.The algorithm firstly constructs a new similarity function by considering the spatial information of the sample points and the class information of a small number of labeled sample points.Then K-nearest neighbor method and genetic algorithm are used to obtain the optimal graph.Based on the optimized graph,the spectral method is used to reduce the dimension of the data.Final adoption the local average pseudo-nearest neighbor method is applied to cluster analysis.In this paper,two classical hyperspectral images SalinasA data sets and Botswana data sets are tested.The results show that the proposed method can achieve high classification accuracy.

A Method for Filling Absence Data of Airborne LiDAR Point Cloud

WANG Liying, XIA Yuhong, XU Yan, ZHAO Yuanding

2018, 0(10):  27-31.  doi:10.13474/j.cnki.11-2246.2018.0309

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For the absence data existed in the airborne LiDAR point cloud, a method for identification and filling the absence data is proposed. The proposed method first detects absence data depending on binary data void image. Next the data void image is segmentd into multiple data voids by means of connected-component labeling algorithm. Then influence region of each data void is obtained by isometrically expanding the outer boundary contour based on the variance and mean curvature criterion. Finally, the optimal spatial interpolation scheme is determined related to different data void types, and then it is used to fill the data voids based on the point clouds in influence region of each data void. ISPRS LiDAR datasets, which are representative of absence data of diverse types, are used to analyze the effectiveness of "influence region" and to detemine the assess optimal spatial interpolation scheme for different data void types. And thus the feasibility and effectiveness of the proposed method is verified.

Oblique Aerial Image Matching Method Based on Dense SIFT and Improved Least Squares Matching Algorithm

YANG Xingbin, LÜ Jingguo, ZHANG Danlu, CHENG Zhe

2018, 0(10):  32-36,70.  doi:10.13474/j.cnki.11-2246.2018.0310

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An automatic tie-points matching method of oblique image is proposed based on Dense SIFT and improved least squares matching to solve the problems of less matching points, uneven distribution and low matching efficiency. Firstly, the approximate orthophoto is obtained by the perspective transformation which the geometric deformation, scale and rotation between images is eliminated. Then pyramid image is built and split into blocks. Feature points are extracted using Dense SIFT algorithm from the top pyramid image block, and matching points are searched based on the KD tree, then the random sampling consistency algorithm is used to eliminate the mismatching points. An improved least squares matching algorithm is applied to correct the location of the initial matching point. Finally, the coordinate of the matching points are obtained by improved least square matching algorithm on all level pyramid images. Images of typical region is selected to test the matching effects, the experimental results show that the method can obtain dense and uniform matching points, and the efficiency is higher than SIFT and ASIFT algorithm.

Effect of Fractional Differential on Soil Hypermetallic Hyperspectral Data at Different Sampling Intervals

JIANG Ming, GUO Yunkai, QIAN Jia, DING Meiqing

2018, 0(10):  37-40,45.  doi:10.13474/j.cnki.11-2246.2018.0311

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In order to study the effect of fractional differential under different sampling intervals on the correlation coefficient between spectral reflectance and soil heavy metal content, the soil spectrum are resampled at 15, 25, 35 and 45 nm intervals, and then the corresponding 0~2 order (interval 0.2 order) differential processing is performed to compare and analyze the variation trend of correlation coefficient between each order differential and the soil heavy metal at various sampling intervals.The results show that when the differential order increases, the number of bands having a significant correlation level of 0.01 generally increases first and then decreases and the effect of improving the correlation by 15 nm resampling interval is better than the other three sampling intervals. And the absolute values of correlation coefficients of 15, 25, 35 and 45 nm reach the maximum in 1.6, 1.2, 2 and 2 orders respectively.

Research on Merging Method for Survey Area of No Photo Control Points

TONG Kuang, ZENG Weibo, WANG Bo, LI Mingkong, CHEN Leilei

2018, 0(10):  41-45.  doi:10.13474/j.cnki.11-2246.2018.0312

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In view of the inaccurate orientation in aerial regulation of various observation areas without photo control points in the process of large-scale UAV oblique photogrammetry due to terrain fluctuation and other reasons,this paper proposes a matching method to divide different no photo control points areas on the basis of the height differences of air route datum between DEMs in contiguous observation areas.This method has a great advantage over the traditional manual matching division in efficiency and accuracy,which is referential and applicable to the data processing of large-scale aerophotography in mountainous areas.

3D Navigation Path Planning of Indoor and Outdoor Integration in Digital Campus

WEI Shuangfeng, HU Bo, ZHANG Xiaoyu, GU Qiuchen, ZHAO Tianyu

2018, 0(10):  46-50.  doi:10.13474/j.cnki.11-2246.2018.0313

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Indoor and outdoor integrated navigation is a current research hotspot. Comparing to the more mature outdoor navigation technology, indoor positioning technology lags behind, so it can not meet the growing demand for indoor and outdoor integrated navigation in real life. For the new intelligent robots or drones technology, the traditional 2D map-based navigation path planning cannot meet the requirements for accurate indoor and outdoor navigation. Therefore, how to quickly and efficiently realize indoor and outdoor integrated 3D navigation path planning becomes an urgent problem. This paper uses campus remote sensing image data, building attribute data and college building floor plan of Beijing University of Civil Engineering and Architecture, based on CityEngine and SketchUp 3D design platform,realizes digital 3D indoor and outdoor fine-scale modeling. Then, we use modeling tools of ArcGIS to extract and plan the indoor and outdoor 3D navigation path network, which can be used for intelligent robots or unmanned aerial vehicles, and provide technical support on integrating indoor and outdoor intelligent navigation.

Research and Application of Temporal and Spatial Network Model for Urban Tourism Flow

DUAN Liqiong, LIU Shaojun, LIU Zehua, CAO Qun

2018, 0(10):  51-55.  doi:10.13474/j.cnki.11-2246.2018.0314

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At present,network structure model and space-time path model are analyzed in the tourism flow.However,network structure model can better describe the flow and flow characteristics of the tourism flow,but it is difficult to describe the dynamic characteristics of its space-time.And space-time path model can better describe the space-time behavior of individual tourists,but it is difficult to describe the overall flow and flow characteristics of tourist flows.Aiming at the above questions,this paper presents a space-time network model of urban tourism flow and it can better overcome the problem that the single network structure model or space-time path model is difficult to express the space-time behavior and agglomeration characteristics of tourism flow at the same time.Finally, taking Tianjin as an example,the space-time network model of tourism flow in Tianjin is constructed dynamically based on the big data of communication.

Sea Ice Distribution Detection Based on FY-3 Satellite MWRI Data

WU Zhankai, WANG Xingdong, WANG Cheng

2018, 0(10):  56-60,65.  doi:10.13474/j.cnki.11-2246.2018.0315

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Based on the MWRI 19 GHz data from the FY-3 microwave imager (MWRI),a new method for detecting the distribution of Arctic sea ice is proposed,using the most polarized characteristics of seawater and sea ice at 19 GHz.Then the polarization difference of 19 GHz is processed by Otsu algorithm to get the classification threshold of seawater and sea ice,and the Arctic sea ice distribution is obtained.The results of sea ice distribution are obtained by taking the data of January 2016 as an example to verify the distribution results of Arctic ice distribution with the North American Ice Data Center (NSIDC).The results show that the average sea ice extent in January based on FY-3 MWRI is 12.905×10⁶ km²,and the sea ice extent provided by NSIDC is 13.493×10⁶ km²,only a difference of 4.35%.And the daily growth rate of the sea ice extent are 0.038 4×10⁶ and 0.041 9×10⁶ km²,respectively.Therefore,it is feasible to detect Arctic sea ice distribution based on the difference of 19 GHz vertical polarization and horizontal polarization combined with Otsu algorithm.

Building Shadow Detection with Integrated Characteristic Components for High Resolution Remote Sensing Images

XIE Yakun, FENG Dejun, LI Qiang, WANG Yinru, HU Minjun

2018, 0(10):  61-65.  doi:10.13474/j.cnki.11-2246.2018.0316

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An object-oriented building shadow extraction method is proposed for high-resolution remote sensing images,which integrates the images characteristic components and the shadow's morphological characteristics of buildings.By analyzing the spectral characteristics of remote sensing images,the first component (PC₁),the green band component (G),the excess green (EXG) and the hue characteristic (H) were constructed,then we used the gamma transform to enhance the H band,and normalized the DN value of each characteristic component and made a comprehensive analysis.According to the morphological characteristics of building shadow,we established the area and aspect ratio rule and built a rule set.Thereby,the object-oriented building shadow information extraction was achieved.Finally,we selected remote sensing images from different regions and time intervals to extract building shadow.Experimental result showed that the proposed method can not only effectively reduce the influence of water bodies,vegetation and dark objects,but also remove the shadow of non-building structures,and then obtain integral building shadow patches without fragmentation.

A Method of Geographic Entity Coding Based on Spatial Features

WANG Yunfan

2018, 0(10):  66-70.  doi:10.13474/j.cnki.11-2246.2018.0317

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In order to meet the need of multi-source heterogeneous spatial data matching during emergency mapping, this paper provides a solution about unified coding of geographic entities from different datasource. Combining open location code and the geometric features of geographic entities, a method of multi-resources data merging is proposed by unifying the code of different geographic entities and their geometric features, along with a similarity calculation model. This method can be applied to GIS data matching and fusion, vector data update, emergency data fusion process, and the matching and fusion of POI in fundamental geographic information and Map World navigation data, which provides data for emergency mapping in the future.

Two-step Semiparametric Model for Compensating the Systematic Errors in Marine Magnetic Survey

LIU Qiang, YIN Xiaodong, ZHAO Junsheng, BIAN Gang

2018, 0(10):  71-74.  doi:10.13474/j.cnki.11-2246.2018.0318

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The improper function model of systematic errors can lead to compensating inaccurately in marine magnetic survey,the semiparametric regression analysis theory is introduced to the two-step processing method,a non-parametric component that represents the model error is added during processing line filtering and estimation,to correct the shortcomings of poor function compensation model of systematic errors,and further to improve the compensation effect of systematic errors.A practical survey data is calculated to prove the efficiency of the method,and it shows that the accuracy of the survey network is obviously improved after compensating by using two-step semiparametric model,and the compensation effect is better than the commonly used simple model and the classic two-step processing method.

Technical Status and Development Trend of Deep Sea LBL

ZHANG Tongwei, QIN Shengjie, TANG Jialing, WANG Xiangxin

2018, 0(10):  75-78,106.  doi:10.13474/j.cnki.11-2246.2018.0319

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As the most accurate underwater acoustic positioning technology, long-baseline (LBL) positioning system can directly provide absolute position information for all kinds of deep-sea detection equipment, and it is widely used in navigational positioning of deep-sea exploration. The basic principle of LBL is introduced in brief. Then the deep-sea LBL systems of iXblue, Kongsberg, and Sonardyne are systematically introduced, and domestic development is also analyzed. Finally, the development trend of deep-sea LBL is prospected, such as rapid baseline calibration, combination of LBL and USBL, combination of LBL and digital underwater acoustic communication, multi-AUV mobile LBL and single beacon-aid navigation.

Feasibility Research on Without Manual Leveling and Centering Survey of Modern Intelligent Total Station

GU Xuanlong, LIU Chenglong, GUO Wei

2018, 0(10):  79-83,92.  doi:10.13474/j.cnki.11-2246.2018.0320

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Research on the measuring technology using intelligent non-leveling and non-centering total station is of great importance in solving practical problems and improving work efficiency.In this study,by comparing the data measured by both leveling total station and non-leveling ones,we conclude that the 3D coordinates measured by non-leveling total stations are accurate while the corresponding X-Y plane is not horizontal and the corresponding Z is not elevation information,but it's accurate space coordinate.Moreover,we discusse the 3D coordinate system when measuring with non-leveling total stations and then propose the thought that spatial angle α、γ can also be accurate measured.The measured space coordinates have been carefully verified by mathematical models,thus proving that the measuring technology using non-leveling and non-centering of modern intelligent total station is practicable and reliable.

Research on Specification System Construction of GNSS Reference Stations

CHEN Ming, ZHANG Peng, WU Junli, ZHANG Qiuyi

2018, 0(10):  84-87,112.  doi:10.13474/j.cnki.11-2246.2018.0321

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At present,there are some problems in GNSS reference stations of our country,such as inadequate co-ordination planning,imperfect regulatory specifications and prominent security risks.This paper proposes to construct a framework consisting of a series of specifications such as construction,operation and maintenance,product and service,quality,inspection and testing,safety management and so on.In this paper,the technical problems to be solved by each specification are studied,and the hierarchical and logical relations of series specifications are analyzed in depth.The goal is to form a benign interaction that promotes the industrialization of BDS navigation and positioning by standardization and the deepening of standardization by industrial development.

A Precise Multi-GNSS Data Processing Algorithm with Double Difference Observations Based on the Normal Equation Stacking Technique

XIAO Yugang, WANG Zheng, CHEN Hua, YU Shougang

2018, 0(10):  88-92.  doi:10.13474/j.cnki.11-2246.2018.0322

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The mathematical models and methods of multi-GNSS data processing are the current focus of GNSS research. In this paper, an effective double-difference algorithm for multi-GNSS is proposed based on the normal equations stacking technique. The formula for unifying the priori values of parameters from different GNSS is derived, as well as the means of removing and re-imposing the priori constraints and the normal equation stacking method. The availability and accuracy of the new algorithm is verified in this paper with the observations from the deformation monitoring experimental platform. The results show that the accuracy for short baselines is better than 1 mm for the horizontal components, 2 mm for the vertical components with this new multi-GNSS data processing algorithm and the GPS/BDS observations, which could satisfy most of the deformation monitoring projects.

Remote Sensing Image Change Detection Algorithm Based on Super-pixel Segmentation and Multiple Difference Maps

XIAO Minghong, FENG Wenqing, SUI Haigang

2018, 0(10):  93-97,121.  doi:10.13474/j.cnki.11-2246.2018.0323

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Remote sensing image change detection is widely used in land use,urban expansion,deforestation,as well as disaster assessment etc.This paper presents a novel object-level change detection method for remote sensing images based on the combined utilization of change vector analysis and spectral gradient difference.Firstly,we utilize the entropy rate segmentation method to segment the image and consider the heterogeneity of super-pixels.By changing the number of super-pixels to obtain the multi-layer super-pixel regions with different sizes and the segmentation results are corresponding to the bi-temporal images.Afterwards,in the spectral space and gradient space,we extract the change intensity image and gradient difference image,and make a fusion with these two change information under different weights.At last,the OTSU threshold segmentation algorithm is applied to get the changed/non-changed results.Experimental results on the sets of SPOT5 multi-spectral images show that the fusion strategy can effectively integrate the advantages of the two methods utilized in our process.Compared to using only one single change information,the stability and applicability of the change detection process are improved.

Research and Application of Utilizing UAV Laser Radar to Perfect the Vehicle-borne Mobile Mapping Systems Data

ZHANG Wentao, ZHANG Weihong, WANG Liuzhao

2018, 0(10):  98-101.  doi:10.13474/j.cnki.11-2246.2018.0324

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Vehicle-borne mobile mapping systems mainly obtain the data along both sides of the road in the scanning process.It will get incomplete data when it gets blocked,and the poor GNSS signal makes the data accuracy descend in partial area,so that it is difficult that vehicle-borne mobile mapping systems complete an engineering task separately.UAV laser radar has high precision data,and there are less covers when measuring in the sky,but the security and detail level of data near the ground are not ideal.Based on the merits,demerits and complementarity between vehicle-borne mobile mapping systems and UAV laser radar,this paper proposed a solution that achieves the high-precision and high-speed data acquisition by using small UAV laser radar to perfect the point clouds data of vehicle-borne mobile mapping systems.The experiment proved that the solution is feasible and can greatly improve the available environment of vehicle-borne mobile mapping systems,so it is good for popularization and applications.

Ground Subsidence Monitoring Using Sentinel-1 Images in Ningbo City

ZHU Bangyan, LI Jiancheng, CHU Zhengwei, WANG Xiao, SUN Jingwen, YAO Fengyu

2018, 0(10):  102-106.  doi:10.13474/j.cnki.11-2246.2018.0325

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MT-InSAR technique based on 21 Sentinel-1 images is used to research ground subsidence in Ningbo during the period of 2016-2018.The InSAR-derived results were validated by leveling surveys.The difference of displacement rates is less than 3.0 mm/a and RMSE is 1.7 mm/a.This shows that the results obtained by MT-InSAR technique agreed well with those measured by leveling.The spatiotemporal characterization of land subsidence in Ningbo is analyzed.The results show that the settlement centers in the study area are not concentrated and have a large number.The value of largest displacement rate is 22.5 mm/a with maximum settlement of 30.3 mm in Haishu.The main traffic roads,subways and railways are partly located in the subsidence area.Taking metro line 2 as an example,the characteristics of ground subsidence in Ningbo are analyzed along the rail transit.

Dynamic Deformation Monitoring and Analysis for Long-span Bridges in Operation Based on GPS/BDS Observations

LIU Zhiqiang, YUE Dongjie, ZHENG Dehua

2018, 0(10):  107-112.  doi:10.13474/j.cnki.11-2246.2018.0326

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The damage detection and safety monitoring of long-span bridges has become more complicated than normal bridges as their span lengths are getting even longer these years. The creep deformation of long-span bridges in operation is usually a process of slow change with relatively small amplitudes. Due to the limit of its inherent positioning capability, the GNSS-RTK technique does not completely meet the precision demand of long-span bridge deformation monitoring. Thus, this paper has explored the feasibility of the continuous pseudo-static monitoring mode based on GPS/BDS observations. An experiment on Sutong cable-stayed bridge was conducted to testify its effectivity with such processing modes as GPS only, BDS only and GPS/BDS combined. The results show that the proposed monitoring mode is highly applicable to precise monitoring of short-termdynamic deformation and analysis of their structure change trends of long-span bridges, which can also be operated automatically.

Application of Air-ground Coordination Survey in Acceptance Measurement for “Guangzhou Circle” Irregular Tower

YANG Guang, LIU Min, WANG Lei, ZHOU Yanfang

2018, 0(10):  113-116.  doi:10.13474/j.cnki.11-2246.2018.0327

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The "Guangzhou Circle" tower is unique in design and complex in structure. This paper introduces low-altitude drones for oblique aerial photography in acceptance surveys, and combines with ground 3D laser scanning technology. The so-called "air-ground coordination survey" has been formed, which greatly shortens the working hours of the field and effectively improves the collection efficiency of the field. It needs of planning approval,and provides a new mode of fine acceptance of major buildings and landmark buildings in the city.

Analysis of Accuracy in High-speed Rail Control Survey of GPS: A Case of Xi'an-Chengdu High-speed Railway

XIA Haining, ZHANG Fanyuyang, YUAN Debao, WANG Jie, PANG Shichen

2018, 0(10):  117-121.  doi:10.13474/j.cnki.11-2246.2018.0328

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This paper introduces the method of GPS applied to high speed railway control survey and accuracy analysis.Using the data collected by the GPS receiver, the three difference model method is used to solve the data.With the new method at home and abroad, the precision analysis is carried out at the present stage, and the data are processed by a variety of means, which makes the precision indexes of the control net results meet the requirements.Because of the difference between the accuracy and the process of the calculation, this paper deals with the problems in the high speed iron GPS control measurement and the analysis of the data processing with the example of the Xi'an-Chengdu high speed rail project.The connection between the network structure and the positioning accuracy of GPS is summarized, and then the GPS net with good precision, reliable results and more economical is provided, which provides theoretical guidance for engineering practice.

Research and Implementation of the Modern Geodesy Database System

WANG Yongshang, ZHANG Peng, WANG Xiaoqing, SUN Zhanyi

2018, 0(10):  122-125.  doi:10.13474/j.cnki.11-2246.2018.0329

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The national geodesy data storage, management and application services develop rapidly recently with the development of the new geodetic technology system. This paper studied the content, characteristics and classification of modern geodetic data, and proposed a real time data storage, management method based on the database DBFS technology, as well as the modeling of all kinds of data entities (observation data class, result data class, summary data class and Auxiliary data Class) are analyzed and realized. To meet the requirements of modern geodetic data acquisition, storage and real-time service, database and management system was optimized, the composing structure and system function of geodetic database realized, and better meeting the requirements of modern geodetic data management and application.

Quantitative Analysis of Urban Development Quality in Hefei City

REN Jiafeng, MA Weichun, REN Chengcheng

2018, 0(10):  126-130.  doi:10.13474/j.cnki.11-2246.2018.0330

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Aiming at the problem of how to comprehensively use geographical national surveys and thematic statistics data to carry out urban development quality assessment, this paper proposes a method of metrological analysis and evaluation based on spatial location. Taking the Hefei city of Anhui province as the research object, this paper selects four dimensions of economic development, social services, ecological environment and residents' lives, 15 secondary indicators and 30 tertiary indicators, and constructs a comprehensive evaluation index system of urbanization quality. Using the methods of spatial analysis, entropy weight and distance between advantages and disadvantages, the urban development characteristics and spatial distribution characteristics of Hefei City were obtained. The research shows that the analysis results of this method are consistent with the actual development and trends of Hefei City. From the dimensions of economic development, social service level, ecological environment and residents' quality of life, the four districts, four counties and one city of Hefei city are compared and analyzed in detail. The quality of development provides a scientific reference for the city's future development planning.

Design and Achievment of the Smart City Management Sharing System

HAN Qingying

2018, 0(10):  131-134.  doi:10.13474/j.cnki.11-2246.2018.0331

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The smart city management sharing system is an important part of the smart city construction.It is a new model of urban management based on a new generation of information technology systems which realises two-way and multi-directional information sharing about space-time entity objects.In view of the actual construction of Taiyuan smart city management sharing system,this article elaborates the important role of the smart city management sharing system construction in urban development and social management from the aspets of system design,database construction and functional realization.

Method of Thematic Map Compilation Based on Knowledge and Model

LIANG Lei, ZHOU Qi, REN Dongyu

2018, 0(10):  135-139.  doi:10.13474/j.cnki.11-2246.2018.0332

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According to the fact that thematic map compilation needs staff owing professional knowledge to process large amounts of geographic data and thematic statistical data and leads to low production efficiency of thematic map design, this paper studies thematic map compilation process and summarizes knowledge system of map content design, layout design, color design,map symbols and decoration design.Then map design process is structured, modeled and stored using information language to construct knowledge rule database.Cartographic model is constructed based on symbolization mechanism of geographic and thematic features.Finally, based on the above method,thematic map integration system is developed using computer programming technology and sample map is compiled using the system.The results show that the paper's methods can improve the efficiency of thematic mapping, and provide powerful technical support for the production of thematic maps.

Teaching Reform Exploration and Practice in the Course of Microwave Remote Sensing

WANG Lihua, LU Peng

2018, 0(10):  140-143,151.  doi:10.13474/j.cnki.11-2246.2018.0333

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In the teaching of microwave remote sensing,there are some problems including indoctrination education,teaching content out of touch with the new microwave remote sensing technology and students lack of thinking and practicing abilities.In view of these problems,we probed into the microwave remote sensing teaching reform.In this paper,we advocated the teaching syllabus as the main line,combined with domestic and foreign teaching materials,professional journals and academic conferences materials as the teaching content.A variety of teaching methods was adopted in parallel,we focused on heuristic teaching,research teaching and practice teaching.For practice teaching,we designed the experimental project,set up the experimental data set and prepared the experimental instructions.On these basis,classroom and extracurricular assignments were helped to consolidate the microwave remote sensing knowledge.Through teaching reform,teachers change the indoctrination or simple question teaching to guide students identifying problems,raising questions and solving problems,which will help students to understand,absorb and utilize the knowledge,further achieve to teachers' propagate the knowledge,impart professional knowledge,resolve students' doubts and improve the teaching and learning together.

Practice of Promoting Learning by Competition in Higher Vocational Geomatics Major

FAN Ben, XU Huixi

2018, 0(10):  144-146,151.  doi:10.13474/j.cnki.11-2246.2018.0334

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Mapping skills competition can greatly promote the improvement of students' practical ability and the cultivation of vocational skills. Based on the competition at all levels, resolving the new promoting learning by competition connotation and teaching characteristics of higher vocational colleges, in order to realize the promotion role of the skills competition on the study of geomatics major students, the practice mode of promoting learning by competition is explored. Measures have been taken to improve the promoting effect by competition such as setting up skills competition selection and teacher's assistant system, establishment of measurement association, establishment of technical innovation and social practice skills, promoting school tradition construction with architecture culture, implementing core skills-examination system, etc. Through these practices, students' professional practice awareness and understanding of professional activities have been improved. Good teaching effect is realized.

Construction and Practice of the Curriculum System of “Post Class Certificate Creation” for Surveying and Mapping Geographic Information Specialty Oriented to Core Literacy

WANG Jing, SHI Junliang, CHEN Lin

2018, 0(10):  147-151.  doi:10.13474/j.cnki.11-2246.2018.0335

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In order to meet the needs of higher vocational training in surveying and mapping geography information specialty, according to the requirements of the graduates' service objects, the employment industry and the job position, this paper, starting with the curriculum system of Engineering Surveying Technology Specialty in higher vocational colleges, has established the professional orientation and talent training goal through full investigation and analysis, and in our hospital. On the basis of the national teaching achievement of the "double certificate" system, the curriculum system of "post course certificate" for surveying and Mapping Specialty of Surveying and mapping oriented to core literacy is established, which makes the graduates not only in accordance with the requirements of employment ability, but also has the potential for sustainable career development, and has been achieved through concrete implementation. Remarkable results have been achieved. The establishment of this curriculum system can provide a reference for our colleges and universities to train applied skills professionals.

Reverse Modeling of Municipal Building and Case Analysis of Building Facade Surveying Based on Trimble TX8

YANG Xuejiao

2018, 0(10):  152-155.  doi:10.13474/j.cnki.11-2246.2018.0336

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The reverse modeling technique of 3D laser scanning measurement has the characteristics of covering all the municipal elements, the fast speed of the real scene surveying, the precision of surveying results, the diversity of information collectionand and the repeatability of the original data, etc.The application of this technology is specially adapted to the city center area, and the municipal measurement application of the complex, multi-class and frequently-updated districts, shops, green plants, roads and ancillary facilities, etc.This paper takes Trimble TX8 ground 3d scanner as an example to discuss the application of laser scanning technology and data results in the surveying and mapping of municipal elements in urban central streets.

A Lossless OBJ File Compression Method for Regular Building

HUANG Hong, ZHAO Zhipeng, ZHANG Lei

2018, 0(10):  156-158,162.  doi:10.13474/j.cnki.11-2246.2018.0337

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Wavefront OBJ file, as an important data exchange format, is widely applied in 3D spatial data visualization. To solve the problems of redundancy structure, too large file size and low network transport efficiency, lossless OBJ file compression model and compression method are proposed to solve the problem on the analysis of building characteristics, and a visual verification is conducted. The result shows that the compression method can compress file size efficiently and improve transport efficiency.

Application of Topcon Sirius UAV in the Large Scale Mapping and Three Dimensional True Modeling

LI Xinlong, LI Weiming, ZHANG Qingmin

2018, 0(10):  159-162.  doi:10.13474/j.cnki.11-2246.2018.0338

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Unmanned aerial vehicle (UAV) aerial survey system has been widely applied in surveying and mapping engineering area. Based on Sirius unmanned vehicle photogrammetry system, 1:2000 scale data of DOM, DEM, DLG are generated in the survey area by using GNSS real time dynamic difference and high precision measurement with data processing technology. Through analyzing the survey area accuracy, the results satisfy the requirement of large scale map specification. Taking the high overlap rate image and precision POS data, the generated data is input to connection client software for 3D modeling processing. The production model can provide data basis for large construction-engineering development. The conculsion shows that Sirius UAV is suitable for surveying and mapping large scale area and 3D modeling, thus providing visual and precise basic data for design and construction deparment.