Table of Content

25 January 2021, Volume 0 Issue 1

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Analysis of two different smartphone pseudo-range smoothing methods

XIAO Qinghuai, BEI Jinzhong, GU Shouzhou

2021, 0(1):  1-8.  doi:10.13474/j.cnki.11-2246.2021.0001

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Aiming at the problems that smartphones are limited by navigation chips and antenna receivers, the accuracy of pseudorange observations is not high, and there are many gross errors. This paper proposes to use the various measurements to detect double differences among epochs in order to find and remove the gross errors in the observed values, and then use the Doppler observations and carrier phase observations to smooth the pseudo-ranges. The reasons that affect the positioning accuracy of smartphones are analyzed from aspects. And the availability of carrier phase observations and Doppler observations for smoothing pseudoranges are explained. The experimental results show that the carrier phase smoothing pseudorange can effectively improve the positioning accuracy; the Doppler observation smoothing pseudorange positioning accuracy is related to the Doppler observations obtained by the navigation chip, and the MI8 Doppler observations have better accuracy than P30.

AGV indoor positioning and navigation with LiDAR map matching and QR code fusion

ZHOU Zongkun, JIANG Weiping, TANG Jian, WANG Yiwen, OUYANG Wenyi

2021, 0(1):  9-12,52.  doi:10.13474/j.cnki.11-2246.2021.0002

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There are various indoor positioning methods for automatic guided vehicle (AGV). LiDAR matching positioning is widely used, but in areas with few characteristic such as corridors, the lack of constraints leads to mismatching. In view of this problem, this paper proposes a combined navigation method of LiDAR and QR code landmarks, and uses turtlebot3 to perform simulation experiments in an indoor corridor environment. The results show that the average error of laser matching navigation is 11.5 cm, The combined navigation method can control the average error within 2 cm. This method can achieve accurate positioning and navigation of AGV in a scene with low characteristics, and improves its adaptability and reliability to the working environment.

Method for detecting yaw angle of indoor robot using visual vanishing point

WANG Cheng, CUI Ximin, CAI Liangli, LIU Huan, ZHANG Jian

2021, 0(1):  13-17,23.  doi:10.13474/j.cnki.11-2246.2021.0003

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While the indoor obstacle map is presented to the user to browse, it is also the basis for path planning and obstacle avoidance of the autonomous motion visual robot. Due to the randomness of the initial pose selection of the autonomous motion vision robot, when the robot walks in a random direction, it often causes the indoor obstacle map to be skewed. In this paper, a single calibrated photo is used to detect the orthogonal vanishing point. Combined with the geometric perspective principle of the camera and the vanishing point geometric characteristics, a simple and fast method for detecting the yaw angle of the indoor robot is proposed. And it is successfully used in the trajectory optimization of the autonomous motion robot and direction correction of the created obstacle map. The comparison experiment indicates that the indoor robot yaw angle detection method based on visual vanishing point has high accuracy. While correcting the orientation of the obstacle map, the robot has a short running trajectory and low time consumption. It has good prospects for promotion and application.

Analysis of GNSS positioning accuracy of single and dual frequency smart phone

WANG Shitai, YANG Shini, LI Xuezhen

2021, 0(1):  18-23.  doi:10.13474/j.cnki.11-2246.2021.0004

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In order to analyze the difference between single-frequency and dual-frequency smartphones in single-point positioning and dynamic navigation, this paper compares and analyzes the number of satellites, SNR, the original observation values and Kalman filtering values in static or dynamic positioning observed by single-frequency and dual-frequency smart phones. The experimental results show that under the static and unobstructed experimental conditions, compared with the original observation value of OPPO Reno single-frequency smartphone, the average positioning error of Xiaomi Mi8 dual-frequency smart phone, which can be observed by more satellites and reduced by 1.70 m. After Kalman filtering processing, the single-frequency mobile phone shows a higher accuracy improvement than the dual-frequency smart phone and the final precision of both is equivalent. Under the experimental conditions of dynamic occlusion, the average value of positioning error of dual frequency is reduced by 5.24 m compared with that of single frequency. After Kalman filtering processing, the accuracy of both has been significantly improved, and the average error of dual-frequency relative to single-frequency is reduced by 0.87 m.

PDR/geomagnetic fingerprint indoor positioning method based on particle filter

WANG Anyi, OU Xue

2021, 0(1):  24-28.  doi:10.13474/j.cnki.11-2246.2021.0005

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Aiming at the problem of error accumulation in PDR positioning and mismatching caused by non-unique geomagnetic fingerprint, this paper combines PDR with geomagnetic fingerprint to conduct indoor positioning research, and proposes a PDR/ geomagnetic fingerprint indoor positioning method based on particle filter. In the PDR positioning process, the map information is used to control the updating of particle weight to obtain more accurate position information. Then, dynamic time structuring algorithm is used to perform rapid sequence matching on the basis of PDR calculated position to obtain the optimal position estimation. The experimental results show that the fusion positioning method can effectively solve the problem of pedestrians’ position passing through the wall. The maximum positioning error is less than 1.5 m, and the positioning accuracy is 1 m with a 53.33% probability.

Monitoring and dynamic analysis of water level of Sarez Lake by remote sensing technology based on ICESat-1/2 laser altimeter system

ZHU Changming, ZHANG Xin, FANG Hui, WANG Weisheng

2021, 0(1):  29-34.  doi:10.13474/j.cnki.11-2246.2021.0006

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In view of the safety problems of Sarez Lake and the difficulty in obtaining hydrological site data, resulting in lack of time-fixed and uniform precision of quasi-real-time lake water level information, this paper proposes a plateau lake water level retrieval method based on space-borne laser altimeter data (ICESat-1/2). Sarez Lake level time series survey is carried out by remote sensing altimetry technology and water level changes in the past 20 years (2003—2019) are reconstructed. Trend analysis and Mann Kendall (MK) nonparametric test are used to analyze the water level variation characteristics of the Sarez lake in the past 20 years. The recent trends and patterns of the water level in Sarez Lake are revealed. The results show that: ①The error of ICESat-1/2 laser altimetry radar data can be controlled within 0.05 m in the inversion of land lake water level. So the accuracy is highly credible, which provides favorited/promised data source for lake hydrological monitoring in no, lack data area. ②During 2003—2019, the water level of Sarez lake still shows a significant upward trend, and the rate of water level raise is about 0.15 m/a (p<0.01, two-tailed). ③The water level of Sarez Lake is highly volatile during the year (7~8 m at least). The highest water level occurs from September to October, the current average water level is about 3265 m; the annual minimum water level appears from March to May, and the current average water level is about 3259 m. The above findings provide data support and technical reference for the comprehensive management and safety assessment of Sarez Lake.

Permafrost deformation in Qinghai-Tibet Plateau time-series PS-InSAR

HONG Zhaoyang, JIN Shuanggen

2021, 0(1):  35-40.  doi:10.13474/j.cnki.11-2246.2021.0007

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The permafrost and the active layer variations are closely related to global climate change and biodiversity. However, the traditional measurements of the permafrost are usually restricted within regionally specific sites and the spatial coverage is limited. In this paper, the C-band Sentinel-1A IW model data with small baseline SAR interferometry (SBAS) technique considering permanent scatterers is used to study the surface deformation and frost-thawing in the Tuotuohe permafrost region of Qinghai-Tibet Plateau. The estimated surface displacement rate (mainly ranging from -20 to 20 mm/a) and displacement time series reflected the evolution of permafrost and active layer. In addition, the results are consistent with the leveling data, and furthermore this method is better than the general multi-temporal InSAR method. In addition, the relationship between SAR imaging geometry and surface displacement is analyzed and the motion trend is better explained, especially for slopes. The results show the monitoring ability of InSAR, which improves our understanding of the surface deformation in permafrost area.

High precision space estimation of housing vacancy rate using high resolution image and Luojia-1

ZHANG Dong, LI Deping, ZHOU Liang, HUANG Jinxia, GAO Hang, WANG Jiacheng, MA Yu

2021, 0(1):  41-46,52.  doi:10.13474/j.cnki.11-2246.2021.0008

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To estimate the house vacancy rate, this paper proposes a method that divides the study area into three parts: high-rise area in the built-up area, low-rise area in the built-up area and non-built-up area. In this method,the accuracy of the estimated results is tested by “night field record”, and the local indicators of spatial association (LISA) is used to analyze its spatial aggregation.It can be found from the results that, ① The overall house vacancy rates in the study area are 17.88%.The root-mean-square error is 0.14. The house vacancy rates in non-built-up areas are higher than that in built-up areas, while the full occupancy rates are lower than that in built-up areas. ② The house vacancy rates in the study area present two spatial agglomeration characteristics: H-H agglomeration and L-L agglomeration. It provides a reference for further information about the vacancy rates of houses in rural areas and the spatial distribution regularity of house vacancy.

Route planning method for UAV inclined photography in complex urban areas

SHENG Hui, LI Linghao, LIU Shusheng, ZHU Junli, LIU Shanwei, SHAO Chengli

2021, 0(1):  47-52.  doi:10.13474/j.cnki.11-2246.2021.0009

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Aiming at the occlusion problem of inclined photography buildings in complex urban areas, a UAV route planning method is proposed. Firstly, the method confirms the height range of the route based on the reconnaissance results of the preliminary survey area, and chooses the proper height and verifies the rationality. Then it confirms the route direction and calculates the overlap degree through the most densely built area. Moreover, according to the critical point of the side view image, the route of this area is designed. This paper takes a large-scale enterprise park as an example to carry out real-life 3D modeling experiments. The relevant results indicate that the 3D model established in the light of this method keeps complete side texture of each building. Compared with the route automatically planned by flight control software, this model has higher resolution, better texture and whole effect.

Comparison and analysis of broadcast ephemeris accuracy before and after Galileo system service interruption

LIU Weiping, XIE Jiantao, JIAO Bo, LIU Jing

2021, 0(1):  53-58.  doi:10.13474/j.cnki.11-2246.2021.0010

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The Galileo service interruption event in mid July 2019 is a relatively rare major accident in the whole history of satellite navigation development. This paper selects the broadcast ephemeris before and after Galileo service interruption, from two dimensions of vertical (using the data of 29 days before and after interruption) and horizontal (comparing with other major systems), through the four aspects of satellite position, speed, clock difference and SISRE (signal-in-space range error), analyzes the calculation accuracy of broadcast ephemeris before and after interruption. The results show that: from the vertical dimension, before the service interruption, the number of Galileo healthy satellites changes dramatically, the accuracy of satellite clock difference is widely divergent, and the accuracy of satellite position and speed is not significantly abnormal. After the service is restored, all indicators return to normal. From the horizontal dimension, compared with GPS, Galileo system has shown better performance in the accuracy of satellite position, speed and clock. In the field of SISRE, Galileo has obvious advantage with an average SISRE of 0.27 m. GPS and BDS have the comparable orbit accuracy. The average SISRE of GPS is about 0.61 m, and that of BDS MEO, IGSO and GEO is respectively 0.76, 0.58, and 0.68 m. The average SISRE of QZSS (IGSO) and QZSS(GEO) is respectively 0.85 and 0.99 m. GLONASS has slightly poor orbit accuracy, with an average SISRE of 1.05 m.

Accuracy assessment of BDS-3 broadcast ephemeris

WANG Zhaohui, MA Xiaping, YAN Li, LU Tieding, ZHAO Qingzhi

2021, 0(1):  59-65,98.  doi:10.13474/j.cnki.11-2246.2021.0011

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In order to evaluate the accuracy of BeiDou-3 global navigation satellite system (BDS-3), broadcast ephemeris timely, this paper makes a comprehensive comparison and analysis of ephemeris error, orbital error and SISRE, signal in space range error. The data of broadcast ephemeris and precise ephemeris is released by Wuhan University of BDS-2 and BDS-3 from March 10 to March 22, 2018 and July 2 to July 14, 2019. The results show that the RMSE of the broadcast ephemeris of BDS-3 are basically better than 1.5 m, and the RMSE of BDS-2 GEO, IGSO and MEO satellites are less than respectively 3.0, 3.0, 2.0 m. The orbit errors of BDS-3 are basically better than 1.0 m, and the errors in the R direction are superior than the T and N directions, respectively 0.1, 1.0, 0.5 m. The orbit errors of the BDS-2 in the three directions of the radial R, T and N are 1, 3, 3 m. The SISRE of BDS-3 are better than 0.25 m, and SISRE of BDS-2 GEO, IGSO and MEO satellites are better than 0.5, 2.0, 0.5 m respectively. The results of this paper reflect that the BDS-3 signal is stable and its accuracy is improved.

Analysis and application of time-varying property of BDS fractional cycle bias

JIAO Bo, HAO Jinming, SHI Chunlin, LIU Weiping, LIU Jing, XIE Jiantao

2021, 0(1):  66-70.  doi:10.13474/j.cnki.11-2246.2021.0012

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Fractional cyclebias can be used in ambiguity resolution of precise point positioning. Its time-varying property has an important impact on the broadcast interval and the data amount of FCB. Since the application of BDS has entered a mature stage, studying the time-varying property and its changes of BDS FCB is conducive to promoting the application of BDS PPP ambiguity resolution.Based on the generation method of single-difference FCB, this paper analyzes the time-varying property of the BDS FCB in 2017 and 2019, and improves the broadcasting interval of the narrow-lane FCB of IGSO satellites. The improved FCB is verified by the fixed-solution PPP of known reference stations.Experiments show that the stability of BDS FCB in 2019 is greatly improved compared to 2017; IGSO satellites can broadcast one group of narrow-lane FCB for one day, which reduce the data amount by 73.4%; the improved FCB can also be effectively applied to the fixed-solution BDS PPP, the convergence speed of which is 43.1% faster than the float-solution PPP.

Study on spatial-temporal evaluation characteristics of urban land expansion for minority nationality regions in Qinghai-Tibet Plateau: taking Haidong city in Qinghai province as an example

REN Jun, ZHANG Fucun, WANG Wanqi, GUO Jing, ZHOU Wei, JIANG Yuxiang, GUO Xiao

2021, 0(1):  71-77.  doi:10.13474/j.cnki.11-2246.2021.0013

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This paper selects the expansion intensity index, compactness, fractal dimension, center of gravity transfer index and orientation proportion index using GIS spatial overlay analysis technology to analyze quantitatively the spatial-temporal differentiation of urban land expansion of Haidong city based on the remote sensing image data from1990 to 2016. The results show that, the urban land area continuously increases, the compactness continuously declines but the fractal dimension continuously increases, the center of gravity mainly transfers to the west and southeast, and the center of gravity of urban land indicates obvious spatial characteristics and shows an tendency of “orderly-disorderly-orderly”, the urban transfers from spatial imbalance to the coordinated development. Moreover, the orientation proportion index shows obvious spatial orientation differentiation characteristics, and the urban land expansion shows coexisting characteristic of single-wing, double-wing, and fan-shaped pattern. Lastly, during the process of urban land expansion of Haidong city, the terrain of the plateau river valley is a natural constraint, the establishment of the new zone and industrial park is the main route, the policy mutation is the main driving force, and the construction of major infrastructure is the driving force guarantee.

Estimation of urban scale NPP by using improved CASA model: taking Xuzhou city as an example

GENG Di, LIANG Liang, HUANG Ting, YAN Juan, WANG Jiahui, QIU Siyi, WANG Lijuan

2021, 0(1):  78-83,89.  doi:10.13474/j.cnki.11-2246.2021.0014

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Due to the characteristics of urban surface Tfeatures, based on different resolution remote sensing data, this paper estimates the NPP of Xuzhou city by using the original and improved CASA, and discusses the improvement of the model and the impact of the spatial resolution of remote sensing image on the estimation results of urban scale NPP. The results show that: ① Urban construction land has a great influence on the estimation results of urban NPP. The improved CASA model zeros the FPAR in construction land, and reduces the estimated value to 15.503 gC·m^-2·month^-1, which effectively removes the impact of construction land on the estimation of NPP in urban areas. ② Low spatial resolution remote sensing data overestimates urban NPP. The average NPP estimated by MOD13Q1+improved CASA model is 18.607 gC·m^-2·month^-1, which is 3.104 gC·m^-2·month^-1 higher than that estimated by Landsat 8 OLI+improved CASA model. The results of this paper provide a new method for NPP estimation at city scale and the scientific basis for carbon sink estimation.

Portraying of different characters based on mobile phone signaling data

WANG Yan, FAN Zixian, LI Chengming, DAI Zhaoxin

2021, 0(1):  84-89.  doi:10.13474/j.cnki.11-2246.2021.0015

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Based on the long-term mobile phone signaling data of Beijing volunteers from Microsoft Research Asia Geolife project from 2007 to 2012, this article conducts research on travel types and portraits based on individuals. This paper proposes a method of character portrait characterization by first classifying user trajectory types based on high-cluster clustering, and then combining travel rules to consider occupation type, age, and hobby attributes. The main conclusions of the study are: ① This paper divides five types of travel including two-point, one-line fixed type, two-point, one-line change type, dual-core type, uniform distribution type, and divergent type. ② Beijing has fixed-work technology people or white-collar workers account for about 44%, and the student group or retired elderly account for nearly a quarter.

A change detection method for low-precision registration remote sensing images

CHEN Shirong, SHEN Peipei, BAO Ying

2021, 0(1):  90-93,98.  doi:10.13474/j.cnki.11-2246.2021.0016

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Traditional methods of change detection for remote sensing images are highly relied on high-precision relative-registration, and mostly cost many broken pieces of polygons which are redundantly or wrongly extracted. In this paper, a rapid low-precision registration dependent method for remote sensing images changing detection is extracted. The method is based on the Perceptual Hash algorithm, which uses both the spectral and texture features as the detection feature sets, makes grid partition of the images as the detection object, calculates the similarity-index of each pair of the grid using the Perceptual Hash algorithm to extract the changing area. Result shows that, the method makes effective promotion of reducing the dependent of the relative-registration precision. The accuracy of correct-extraction can stay 95%, and the incorrect-extraction rate is lower than 5%, with a registration-shift within 15 pixels, which is robust for the registration precision.

Technology of UAV remote sensing image mosaic technology combining SIFT features and poisson fusion

ZHOU Jie, XIE Kun, FU Chao, SHI Kun

2021, 0(1):  94-98.  doi:10.13474/j.cnki.11-2246.2021.0017

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Aiming at the research of UAV remote sensing image mosaic technology, a seamless mosaic method of UAV remote sensing image combining scale-invariant SIFT feature points with overlapping transition Poisson fusion is proposed. The method firstly uses SIFT algorithm to extract the feature points of the image. the feature points are coarsely matched according to the euclidean distance between the feature descriptors. Then the random sampling consistency (RANSAC) algorithm is used to remove the mismatched point pairs. In order to prevent the calculated single adaptive matrix linear structure instability, the LM (Levenbeg-Marquardt) algorithm is introduced to optimize the single adaptive matrix. Finally, the overlapped transition poisson fusion algorithm is used to achieve the seamless mosaic of the image. The experimental results show that this method has advantages in UAV remote sensing image mosaic and can obtain good mosaic image.

An improved SURF method on the visual image area

QIAN Xuefei, SHEN Yingzheng, WANG Youkun, CHEN Yu, XU Bo

2021, 0(1):  99-102,107.  doi:10.13474/j.cnki.11-2246.2021.0018

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Visual images always have the problem of complex texture and dynamic blur, and seriously reduces the similarity of various features between continuous images, and makes it difficult for traditional matching algorithms to obtain accurate, stable and well distributed image matching, then affects the acquisition of all kinds of information in subsequent image processing. In order to solve these problems, this paper proposes an improved surf visual image matching method. The method includes three steps: feature extraction, initial matching and corresponding matching. Firstly, SURF feature matching method is used to extract enough and well distributed feature points; secondly, initial matching is carried out to obtain some correct matching point pairs and the initial projection transformation relationship between image pairs; finally, geometric correspondence matching strategy is used for matching propagation to obtain more reliable matching results. Through the geometric relationship between image pairs, geometric correspondence matching can find more suitable matching results than the original surf algorithm. The experimental results of the TUM data synthesis show that the algorithm is simple and fast, and the matching accuracy is high.

Construction method of real scene 3D monomer model based on oblique photography

GUO Rubao, HAO Lijuan, LIU Xudong, LIU Jun, LIU Yaohui, ZHANG Wei

2021, 0(1):  103-107.  doi:10.13474/j.cnki.11-2246.2021.0019

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The 3D real scene model of oblique photography is composed of a continuous triangular net through texture mapping,and each geographic element on the model has the characteristic of “a piece of skin”. In view of the existing problem of the inability to manage and edit the geographical objects on the model, this paper proposes a technical method for single modeling based on oblique photography real scene model. Firstly, the method of fully automatic construction based on Street Factory’s real-scene 3D model is discussed by using oblique photography technology. Then, based on the generated three-dimensional real scene model, the single modeling method of the oblique photography real scene model is used to complete the construction of the geographical object single model and the attribute database connection. This paper takes the urban area of Tumote Right Banner as the test area. Through the accuracy analysis of aerial triangulation, the accuracy of the construction of the 3D real scene model in this paper is effectively verified. It provides convenience for the query, management and application of the geographic object attributes in the model, effectively expands the application field of model data and has certain reference value for the construction of smart cities in Inner Mongolia.

Construction and application of high-precision three-dimensional monomerization model for urban scenes

SUN Songmei, HUANG Tianjin, SUN Ying

2021, 0(1):  108-111.  doi:10.13474/j.cnki.11-2246.2021.0020

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Oblique photogrammetry can perceive complex urban scenes with large scale and high-precision in a real-time and comprehensively. Furthermore, the technology obtains real facade texture while acquiring an orthograph, which guarantees the construction of three-dimensional models of urban scenes. This paper analyzes the necessary technology of urban three-dimensional monomer model measurement, and classifies the monomer model according to the types of urban elements by studing the fusion of two-dimensiona and three-dimensiona data. The fine monomer results have been applied in the construction of 665 km² urban three-dimensional model in Baiyun District, Guangzhou. It has been importantly used in the construction of the models, which not only improves work efficiency, but also reduces field labor intensity.

Design of a fast tracking and positioning system forlong range moving target

WU Yong, GUO Xiaomin

2021, 0(1):  112-115.  doi:10.13474/j.cnki.11-2246.2021.0021

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In order to track and locate the vehicle target in a long distance, a positioning system based on single camera and laser rangefinder are designed in this paper. The single camera photography, laser rangefinder and angle sensor are equipped for this positioning system. LK optical flow algorithm is used to track the target in real time, the coordinate equation model of camera, rangefinder and target is constructed, so it can track and calculate the position of moving target from 100 meters to 300 meters in real time. The positioning system does not need to install any facilities on the tested moving target, so it can track and locate the cooperative or non-cooperative target. In this paper, a high-precision CORS system is used to verify the accuracy. The accuracy of the system for real-time tracking and positioning of vehicle target is kept at the sub meter level.

Construction of nested pyramid model based on linear reference

ZHAI Jialei, HUO Liang, SHEN Tao, DUAN Yuanjing, ZHANG Xiaoyong, FU Jiying

2021, 0(1):  116-120.  doi:10.13474/j.cnki.11-2246.2021.0022

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In view of the lack of effective spatial data model in the construction of linear reference virtual scene, this paper proposes a nested pyramid model construction method based on linear reference based on the current mainstream pyramid model, spatial index structure and dynamic segmentation.Firstly, the dynamic segmentation technology is expanded by combining with the data characteristics of linear scenes, and the vertical structured pyramid model is added.Secondly, the linear reference is statically segmented in multi-scale, the independent arcs are stored separately, and the static segmented pyramid model is constructed.Finally, a unified mapping relationship is established, and a nested pyramid model is constructed, so as to improve the continuity of the model when switching between scales and complete the unified organization and integrated management of multi-source data of linear scenes.

Construction and application of field investigation support platform for land spatial planning based on geoserver

DAI Yao, DUAN Zengqiang, AI Dong

2021, 0(1):  121-123,147.  doi:10.13474/j.cnki.11-2246.2021.0023

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Basic data and satellite images, such as topography, soil, cover type, social economy and so on, are very important for planning, and many of the data are scattered among multiple internet resources and researchers. With the help of cloud server, this paper constructs WebGIS service with the assistance of GeoServer and publishes thematic map information on OpenLayers as the client, so as to provide basic information related to natural environment and social economy for territorial space planning.

Evaluating livability of urban space with consideration of the interactive characteristics of ecological-living-productive spaces: a case of Wuhan city

ZHANG Chenwei, CHEN Kaiqi, GUO Yiwen, WANG Da, ZHAO Bingbing, WU Yan

2021, 0(1):  124-129.  doi:10.13474/j.cnki.11-2246.2021.0024

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From the perspective of the function of ecological-living-productive spaces, the classification index system of ecological-living-productive spaces is established by integrating multi-source geographic data, and the evaluation method of urban spatial livability is further proposed by considering the spatial interaction characteristics. This paper identifies the ecological-living-productive spaces pattern of the central urban area of Wuhan, and evaluates the livable level of this region. The results show that: ①The whole distribution of ecological-living-productive spaces in the central urban area of Wuhan is uniform, showing a spatial distribution pattern of the living space center gathering, the production space scattered around, and the ecological space range is large but small quantity; ②The spatial mixing degree of the ecological-living-productive spaces in Wuhan is low, spatial function types of most the urban areas are single; ③Affected by the adjacent space, the areas with higher livability are located in the edge of the central urban area.

Research on dynamic updating technology of provincial geographic information

LI Siyu, GONG Jing, YANG Jun

2021, 0(1):  130-137.  doi:10.13474/j.cnki.11-2246.2021.0025

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At present, production mode of surveying and mapping geographic information is still mainly consist of traditional large-scale, periodic and full-feature production methods, which is caused by lacking data standards, production coordination mechanism, technological process and supporting software system for updating data collection, processing and storage, extraction and distribution, mapping and slicing, publishing. This paper studies the entire process of geographic information update from following aspects: important geographic information data standards, geographic information change discovery, production scheduling update, field data collection, database update and publishing, proposes a dynamic updating process and production organization model of 1∶10 000 basic geographic information data and “Tianditu” data, with which to form a provincial geographic information dynamic updating technology system.

Reflection on the application of deep learning method in “multiple-investigation-coordination” in Shenzhen

SUN Wei, LI Sheng, JIANG Yi, KE Shuisong, XIA Anke

2021, 0(1):  138-141.  doi:10.13474/j.cnki.11-2246.2021.0026

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Multiple-investigation-coordination is an effective method to achieve data fusion from varies kinds of investigation activities which solves the problem of heterogeneity and conflict of data source. The foundation of the work requires not only unified investigation and estimation system but also synchronously pushing forward the basic investigation and special investigation based on the local circumstances. As a result, to make sure the correctness of acquisition of investigate unit of special investigation, the first priority is to keep the validity of the basic unit division. Moreover, the correctness of classification in the both investigating activities should be guaranteed. In the paper, we consider the application prospect of deep learning method of image classification and object recognition in the “Multiple-investigation-coordination” works in Shenzhen in order to reduce the human labor compared with traditional outdoor investigating tasks and analyze how to improve the accuracy of the classification result. With the continuous improvement of deep learning method, the effectiveness of such method applied in the natural resource investigation activities will enhance constantly.

Intelligent surveying and mapping oriented digital photogrammetry curriculum reform and practice: taking digital photogrammetry course of nanjing university of information science and technology as an example

ZANG Yufu, ZHU Shanyou, JIN Shuanggen

2021, 0(1):  142-147.  doi:10.13474/j.cnki.11-2246.2021.0027

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Recently, many intelligent technologies (such as internet of things, cloud computing and big data) have been penetrating and integrating surveying and mapping science, raising new claims for curriculum of digital photogrammetry. This paper analyzes the limitations of digital photogrammetry curriculum in Nanjing University of Information Science and technology (NUIST), including less connection between knowledge points, archaic curriculum system, monotonous practical teaching. We put forward the following changes: constructing pyramid teaching objectives, creating dynamic teaching module to cover hot technologies, forming applications connecting the knowledge points, constructing problem driven practical teaching to achieve the initial curriculum reform. Comparison to the survey results before the reform shows that the new curriculum system exercises students’ ability in knowledge understanding, programming skills, communication and cooperation, and literature retrieval, which proves the effectiveness of the curriculum reform and provides experience for other similar courses.

Design of teaching contents for introduction to remote sensing under large category cultivation mode

SHEN Huanfeng, LI Huifang, ZENG Chao, LI Quan, HUANG Wenli, WU Chen, ZHANG Hongyang

2021, 0(1):  148-151.  doi:10.13474/j.cnki.11-2246.2021.0028

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The large category cultivation is becoming an important trend for the talent cultivation reform in Chinese universities. As one of the six main curriculums in the large category of resources and environments in Wuhan university, it is urgently necessary to construct thorough teaching contents of introduction to remote sensing by considering the specific characteristics of different disciplines comprehensively. In this paper, the teaching contents of the remote sensing courses adopted in various universities in China are investigated,and their characteristics are analyzed. By integrating the content, the structure, the logic and the practice, it proposes four principles for the design of the teaching contents of introduction to remote sensing. Based on that, the comprehensive teaching contents are constructed, through stringing the data acquiring-processing-application link together.

Teaching reform of digital mapping practice based on virtual simulation experiment platform

GUO Baoyu, WU Baichao, YU Kun, ZHANG Shaocheng

2021, 0(1):  152-156.  doi:10.13474/j.cnki.11-2246.2021.0029

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The software development and application of surveying and mapping practical activities under the background of virtual simulation technology is the pursuit of the current era of surveying and mapping development. Until the advent of the "Digital Surveying and Mapping Simulation Experiment Software" developed and launched by Guangzhou South Surveying and Mapping Technology Co., Ltd., it initially satisfies the current surveying and mapping virtual platform requirements for the teaching reform of simulation experiment. This article further proposes the teaching organization method and assessment method based on digital surveying and mapping teaching reform in virtual simulation practical platform,and provides reference for further promoting the practical teaching reform activities under virtual simulation.

Multi-construction parameter shield construction attitude prediction based on machine learning

XIA Hanyong, YIN Hejun, XU Jiaohuang, WANG Jiawei, HUANG Yi

2021, 0(1):  157-160,164.  doi:10.13474/j.cnki.11-2246.2021.0030

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This paper proposes a multi-construction parameter shield construction attitude prediction method based on machine learning, analyzes the construction parameters of shield tunneling in complex environment, analyzes the internal relationship between tunneling parameters and shield attitude, and establishes the predicted shield attitude. The prediction model realizes the deviation calculation between the center coordinates of the shield head and the design axis. Combined with a subway construction section, the prediction model is verified.

Application of automatic measurement system for dual-mode shield

WANG Xin, ZHANG Li, WANG Shu, WANG Huiqin

2021, 0(1):  161-164.  doi:10.13474/j.cnki.11-2246.2021.0031

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This article describes the principles of the existing laser target guidance system and prism guidance system, analyzes the reliability of the pose measurement of the two systems in the tunneling process, and then proposes a dual mode combining laser target and prism to improve system reliability. The shield automatic measurement system provides a scheme for verifying the accuracy of the pose data, and combines engineering examples to analyze and verify the feasibility of the scheme.

Metro tunnel structure inspection based on vehicle-mounted laser scanning

CHEN Xiangyang, HOU Gangdong, PAN Kai, LI Chengcheng

2021, 0(1):  165-168.  doi:10.13474/j.cnki.11-2246.2021.0032

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Aiming at the basic content and requirements of metro tunnel structure inspection, based on vehicle-mounted laser scanning technology, this paper studies metro tunnel structure inspection methods. The on-vehicle laser scanning system is used to collect the point cloud data of the subway tunnel. The combined filtering method of the RANSAC algorithm and the scale normal algorithm is used to pre-process the point cloud data. By slicing, fitting and unfolding the point cloud data of the tunnel processing, it calculates and analyzes the cross-section deformation, convergence value, stagger value and leakage value of the subway tunnel. The research results show that the vehicle-mounted laser scanning technology can quickly detect and analyze the deformation of the subway tunnel structure, which is suitable for the regular inspection and deformation analysis of the subway tunnel structure.