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Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Road traffic flow is an important feature to measure the importance of the road. Based on the GPS trajectory data and road network data, this paper proposed a novel method for the selection of road network considering both the commonly used geometric features (i.e. length, topological connection, distribution density, closeness and betweenness) and the sematic information-long - term week average traffic flow of the roads. Firstly, in order to ensure the continuity of the road network at small scale, the strokes of the original road network are obtained by using the continuity and direction constraints of Gestalt laws. Then, the geometric features and the traffic flow information of each strokes are computed. Further, a global measure is defined based on the geometric features and traffic flow information, and the weights between the length, topological connection, distribution density, closeness, betweenness and traffic flow are determined using the modified entropy-weight method. Finally, the proposed method of this paper is verified by using Wuhan road network data and taxi GPS trajectory data. The experimental results show that the proposed method can maintain the connectivity of the original road network and tend to select the important roads that are consistent with the human perception. On the other hand, this method can be used to discover the roads that are designed as high-level roads but in contrary rarely used in reality for applications such as urban road network planning and reconstruction. [ABSTRACT FROM AUTHOR]

This study aims to explore building education capacity to improve disaster management in public awareness. We can improve public awareness of disaster risks through public education on landslide disasters. The current education in disaster courses is mainly aimed at students and ambulance personnel. Those education methods focus on textbook teaching and professional training, and the contents are too professional. There is no effective communication channel between educators and the public. Thus, this paper proposes a visual representation method of landslide disasters for public education. We prepared a concept map to organize and represent bits of knowledge of landslide, instantiating nodes of concept map as animation, then used animation to publicize. The landslide on June 24, 2017 in Diexi, Maoxian was selected to conduct a case test analysis. One short animation created by the method and one brief disaster report summarized by that animation is produced for a questionnaire. We collected and analyzed the results of the questionnaire. The results show that people tend to learn about landslides by watching animation, and they answer more questions correctly in the questionnaire after watching animation than reading the report. So the proposed method in this paper can effectively construct the visual content of landslide disaster knowledge and quickly help the public understand the landslide disaster knowledge. [ABSTRACT FROM AUTHOR]

The development of ICT (information and communications technology) provides new challenges and opportunities for modern cartography. Totally different from the traditional cartography in the fields of the research methods and themes, modern cartography trends to digital cyberspace from paper map, and cartographic theories are urged to be improved. However, the understanding of the theories about cartographic virtual space have great differences within the professional domain, and the internal contradictions and transboundary invasion make map gradually become an appurtenance of Internet products. To learning from certain domains to analyse and handle them, challenges have prompted cartographic scholars to explore new fields. The development of “digits and culture” has pushed the game to the forefront of hightech. Games are often geographically significant, and maps of game are a combination of ICT and maps. Based on the cyberspace in game map with instances as the research subject, this paper explores the characteristics and essence of game map and its implications to the real physical world by the dimensionalities, interactivity, narrativity, exploration and cultural dissemination of game maps to discover the extension of cartography, which would replenish and perfect modern cartographic theory and promote its development. [ABSTRACT FROM AUTHOR]

Objective: The construction of disaster reduction system plays an important role in scientific disaster prevention and reduction. Considering that the monolith architecture is difficult to meet the requirements of current disaster prevention and reduction, this paper designs an integrated disaster reduction intelligent service system framework that combines the micro-service architecture and middle platform concept together. Methods: Firstly, by analyzing the characteristics of the micro-service architecture, middle platform concept, as well as the concept and demand of comprehensive integrated disaster reduction intelligent service system, the advantages of using middle platform and micro-service architecture to build the disaster reduction system are summarized, which are high scalability, high fault tolerance, high cohesion, low coupling and so on. Secondly, a system architecture is designed based on middle platform concept. The system architecture is divided into 4 layers which are application system layer, middle platform layer, micro-service layer, and infrastructure layer. We detail the modules and functions of the middle platform, which can improve the development efficiency, reusability, responsiveness and stability of system. Then the implementation path of system based on micro-service architecture is introduced. Results: By implying the above architecture, a geographic information service platform for emergencies in Tibet Autonomous Region is build. The construction path and the main function of the system is introduced, it can not only provide basic functions such as map calculation, query, point of interest(POI) selection, but also provide emergency analysis models including path analysis, shelter location analysis, hazardous area analysis and so on, in addition, a portable system based on mobile phone is also established, which can provide basis browsing, comprehensive information query, emergency thematic information service and so on. Conclusions: The integrated disaster reduction intelligent service system is designed with the micro-service and the concept of middle platform, and by utilizing the proposed framework, this paper realizes the construction of the geographic information service platform for emergencies in Tibet Autonomous Region, which makes the constructing of disaster reduction system more efficient, flexible and practical, and this paper can partly provide reference for the construction of disaster reduction system. [ABSTRACT FROM AUTHOR]

With the development of China’s rail transit system, the transfer problem directly affects the convenience of hundreds of thousands of passengers day after day, and has become an important factor which affects the operation of public transportation systems. The problem of public transportation transfer should be “people-oriented” and analyzed from the time and space mode of passengers' transfer. Based on the smart card data (SCD) of Wuhan City in March 2015, this paper studies the time-space characteristics of passenger transfer, analyzes the current situation of rail transit development, and summarizes the transfor travel mode. The research results are as follows:① In the process of the development of rail transit in Wuhan, the imbalance of rail transit services has arisen and a single-center urban structure has emerged. ② The geographical characteristics of transfer behavior are related to the city’s own geographical pattern, and three factors which influence the transfer behavior are proposed. ③ Using intelligent bus card data, it can effectively identify the social behavior of passengers (transfer behavior) and the time and space mode of passengers traveling. This paper analyzes the spatiotemporal patterns of travel behaviors such as transfer behavior and urban planning and urban space utilization from the perspective of “people-oriented” based on the analysis of big data. [ABSTRACT FROM AUTHOR]

Spatial ‐ temporal analysis method provides technical support for epidemiological investigation. To analyse and demonstrate the transmission of coronavirus disease 2019(COVID‐19), this paper takes the data of COVID ‐ 19 cases in Shenzhen as an example, combines epidemiological investigation knowledge with geo ‐ location linked association analysis, and uses the spatial ‐ temporal five ‐ tuple model to structure and analyze the case data. Rules based on spatial‐temporal five‐tuple model for case type judgment and statistical analysis are defined, which can use spatial‐temporal overlap principles to judge two types of cases, input cases and contact cases, and to make temporal statistics and zoning statistics about the confirmed cases. This paper defines the five‐tuple model and its operation rules for judging and analyzing the epidemic gathering situation, which can use the principle of spatial‐temporal overlap to judge and mine the epidemic gathering situation and to analyze its propagation process. Combined with GIS spatial‐temporal visualization, the entire process of epidemic developments and transmission are displayed in the maps with interactive interface along with temporal series diagrams and social relationship diagrams. During the spreading stage of the epidemic situation, by updating the case data and implementing the analysis, the spatial‐temporal five ‐tuple structure and its operating rules could be feasible to judge, deduce quickly and show the changing status of the epidemic simultaneously with their visualization. The spatial‐temporal five‐tuple model combined with visualization technology can effectively display the distribution and transmission of the diseases, health or hygiene events, and provide support for disease control agencies to understand and control the spread of epidemic conditions. [ABSTRACT FROM AUTHOR]

In cities, the main source of air pollutants is vehicle exhaust. It has become an urgent problem for many cities to explore the law of vehicle exhaust diffusion and actively seek for improvement measures. At present, there are many researches on the simulation of vehicle exhaust diffusion, but few on the modeling of diffusion process and volume visualization analysis. This paper integrates California line source dispersion model‐4(CALINE4) model and 3DGIS to solve the problem of urban vehicle exhaust diffusion simulation and dynamic visualization. Firstly, a street‐scale framework of vehicle exhaust diffusion simulation and visualization is established, and a continuous concentration field is established to express the diffusion processing. A unified data model is used in the semantic space to integrate the data of buildings, roads, trees and dynamic diffusion process data. Secondly, a graphics processing unit ‐ based direct volume rendering method is used to visualize the dynamic diffusion data, and this algorithm is improved in real‐time gradient calculation, texture sampling and time‐based interpolation. Finally, this paper analyzes the vehicle exhaust diffusion of a road in the central business district area of Beijing. The experimental results show that the coupling application of 3DGIS and CALINE4 model can better reveal the spatial and temporal distribution characteristics of urban vehicle exhaust and concentration, which verifies the reliabless and efficiency of the proposed method. [ABSTRACT FROM AUTHOR]

Ionosphere is an important part of the near-earth space environment, and it has an important impact on radio communication, satellite navigation and positioning. Therefore, monitoring the ionospheric morphology is helpful to understand the spatiotemporal changes of the ionosphere and predict the ionospheric morphological characteristics. With the development of global navigation satellite system（GNSS）,ionospheric monitoring has become an important research and application direction. This paper systematically introduces the research progress of multidimensional GNSS ionospheric monitoring and its application in related aspects. It mainly includes space-based/ground-based GNSS joint inversion of ionospheric characteristic parameters, tomography inversion of ionospheric three-dimensional structure, ionospheric delay modeling, ionospheric abnormal disturbance monitoring and mechanism cognition. [ABSTRACT FROM AUTHOR]

Digital development has been vigorously promoted in China to drive a comprehensive and indepth change in production, life and governance through the construction of digital economy, digital society and digital government. It has put forward new and higher requirements for basic surveying and mapping products and services. Recently, the Ministry of Natural Resources of the People􀆳s Republic of China issued a notice to promote the construction of 3D realistic geospatial scene of China, aiming to develop new 3D geo-spatial information products which can describe and represent the real 3D spaces of industrial production, living environment and ecological development. The construction of such 3D realistic geospatial scene of China will lead to a 3D digital space which can be well connected with the real geo-spatial space through real-time inter-connection, and will provide a new generation of spatiotemporal information framework for the development of digital China. It is not only a major task for national and local basic surveying and map‐ ping agencies in the next few decades, but also a challenging scientific and technological initiative where several complex factors and technical problems remain to be solved. This paper analyzes the background and problems, discusses the development directions and general technical logic, and conductes the major technological path. [ABSTRACT FROM AUTHOR]

Objectives: Coastal sea level rise poses direct threats to human livelihood. It is of scientific im‐ portance to understand the causes and provide useful strategies for adapting sea level rise. This paper aims to investigate the causes of coastal sea level change using satellite altimetry, satellite time-variable gravity, and Argo floats. Methods: Given that time-variable gravity suffers from serious leakage issue over coastal area, we use land mass variations from a mascon solution to simulate the leakage from land into oceans, which is estimated to be 0.68 mm/a. Results: On seasonal and non-seasonal scales, satellite altimetry measurements are well explained by the summation of time-variable gravity and Argo floats, demonstrating the closure of coastal sea level change. Satellite altimetry suggests a rate of 3.32±0.45 mm/a for coastal sea level rise, but the summation of time-variable gravity and Argo floats yields a rate of 2.25±0.51 mm/a. Conclusions: The rate discrepancy is about 1 mm/a in coastal sea level budget, which suggests that closing the sea level budget for coastal zone is challenged by uncertainties. The in situ measurements are sparse for Argo over coastal zone, which may underestimate the steric trend. Furthermore, leakage correction and vertical land motion may also cause uncertainties. [ABSTRACT FROM AUTHOR]

Marine and airborne gravimetry is principal to obtain marine gravity field information. To meet the practical requirements of building and expanding of civil military integration system of marine and airborne gravity surveying technology, we have been devoted to the research on theory and method of marine and airborne gravimetry and its application. A detail analysis and review is made based on the research results with theoretical significances and practical values. The study of marine and airborne gravimetry and its application, which are achieved by our research team, mainly covers demand demonstration and top-level design, observation data reduction and accuracy evaluation, observation error analysis processing and separation compensation, upward continuation of observation gravity on the Earth’s surface, downward continuation of airborne gravity, construction of gravity data model at sea, approximation of the Earth’s external gravity field and geoid refinement, etc. The research background, idea and breakthrough point of each topic, and the applicable prospect of research results are mainly analyzed and summarized. We pay our attention to the design of technical framework, the building of variation character models of marine gravity field and the surveying line layout for marine gravity survey, the design of key technical targets for marine and airborne gravimetry, the rising mechanism and compensation of marine and airborne gravity surveying errors, the integrated application of marine and airborne gravity measurement data, and so on. This paper can provide a reference for the future development of marine and airborne gravimetry. [ABSTRACT FROM AUTHOR]

The optimal allocation of land‐use is an important technical means to solve the contradiction be‐ tween supply and demand of land resources and to coordinate social and economic development with eco‐ logical protection, and it is also one of the key issues that need to be solved for the sustainable use of land resources. With the development of spatial simulation and intelligent optimization technology, the theoretical basis and methodological system of land‐use optimization are constantly updated. Based on bibliometrics analysis, this paper systematically summarized the driving theories and methodology of land‐use optimal al‐ location at home and abroad, focused on the application of spatial simulation models and intelligent optimization models in land‐use optimization problems, discussed and prospected the challenges and the future development of optimal land‐use allocation, and put forward that: The coupling drive of natural and human processes, spatial collaboration of multiple models, embedding big data knowledge mining methods, and the support of digital twin technology, should be the research direction of the next stage in the field of optimal land‐use allocation. [ABSTRACT FROM AUTHOR]

Establishing a unified global height datum is one of the core objectives of the international geo‐ detic scientific community, and also a necessary infrastructure for geoscience research on a global scale and cross-border engineering applications. The international geodesy association (IAG) released the definition of international height reference system (IHRS) in 2015 and then in 2019 set out the goal of establishing the international height reference frame (IHRF). In this paper, the theory, methods and practical problems re‐ lated to the IHRS and IHRF are reviewed and studied on the basis of the theoretical foundation and defini‐ tion of the global height reference system. The main research contents include the determination of gravity potential W0 of the global geoid, the determination of gravity potential based on high degree gravity field model, and the determination of gravity potential based on regional gravity field modeling. Two typical in‐ vestigation cases are Colorado geoid model experiment organized by IAG and the realization of IHRS in 2020 Qomolangma height survey. The results of two typical cases demonstrate that the accuracy of gravi‐ metric geoid model can reach 1 cm (0.1 m² /s² in gravity potential) in flat areas and general mountainous areas, and it is expected to reach 2− 3 cm accuracy (0.2− 0.3 m² /s² in gravity potential) even in very complex mountainous areas such as Mount Qomolangma. Based on the results of two case studies, a preliminary strategy for establishing the IHRF is proposed, including layout plan of IHRF reference stations, determination methods of IHRF related gravity potential, data requirements, standards/conventions to be followed and expected accuracy. In addition, we prospect the potential contributions of optical atomic clocks and relativistic geodesy to the unification of global height datum. [ABSTRACT FROM AUTHOR]

The refined seafloor topography models play an important role in fields of submarine plate tectonic movement, underwater carrier navigation support and marine resource exploration and so on. This paper reviews the development of seafloor topography detection technology and model construction, and discusses the current research status and main challenges of the global refined seafloor topography modeling. Also, the developing trends of global seafloor topography modeling are summarized, considering that the technology of recovering seafloor topography from altimeter-derived marine gravity anomalies is still the main way to construct global seafloor topography models. New altimeter satellites such as dual satellite tandem altimeter and surface water ocean topography will provide data sources for further improving the accuracy of marine gravity field and seafloor topography models. Optimization of seafloor topographic inversion theory based on topographic complexity is expected to bring theoretical innovation. It is worth paying attention to explore the application of artificial intelligence technology in global seafloor topography modeling. [ABSTRACT FROM AUTHOR]

On September 16th, 2021, general secretary Xi Jinping pointed out in his congratulatory letter to the first international summit on BeiDou scale application: At present, the development of global digitalization is accelerating, and spatiotemporal information, location and navigation services have become an important new infrastructure. With the advent of the new infrastructure era, people engaged in surveying and mapping should think about what the country wants, be anxious about what the country is anxious about, and devote themselves to the wave of “the second 100 years” and “new infrastructure”. Firstly, this paper expounds the definition of new infrastructure, and analyzes the difference between new infrastructure and traditional infrastructure. Secondly, it discusses the mission of geo ‐ spatial information science in the three systems of new infrastructure, including information infrastructure, integration infrastructure and in‐ novation infrastructure. The authors believed that we have walked through the so called traditional surveying and mapping which mainly serves topographic maps, and developed into the so called ubiquitous surveying and mapping which mainly focuses in the services of geo ‐ spatial information. At present, we should seize the opportunity and expand the new mission of geo ‐ spatial informatics science in the new infrastructure era, provide spatiotemporal data with good integrity, strong reality and high accuracy for the new infra‐ structure, and realize digital industrialization, industry digitization and intelligence. [ABSTRACT FROM AUTHOR]

This paper introduces the current situation of constructing the seafloor geodetic network from de‐ sign, layout, measurement, and data processing. Based on the requirements of national ocean strategy and the development of marine geodetic technology, the problems of the construction of seafloor geodetic net‐ works at the present stage are analyzed. According to the results, it can be concluded the coverage of the current seafloor geodetic network is limited, and the information sharing is insufficient. In addition, the de‐ sign and layout principles are not combined with the positioning precision of the network, which are mostly qualitative descriptions and lack operability. The accuracy and resolution of the sound velocity field are low and the measurement and data processing are difficult to meet the requirements of large-scale and high-pre‐ cision underwater PNT（positioning，navigation and timing）network construction. To solve the mentioned problems, the concept of constructing the underwater PNT network with remote communication, informa‐ tion interconnection and telemetry is put forward. Several key technologies, including the design and layout of the underwater PNT network, the construction of the ocean sound velocity field with high precision and high resolution, the measurement strategy, data processing method and the thought of self-calibration and self-maintenance for underwater control points, the function of target and environment telemetry and sensing services, are discussed to provide support for the new generation of high-performance marine geo‐ detic survey and the construction of underwater PNT network. It is believed that the proposed network sys‐ tem will lead to a revolution in underwater PNT construction when problems such as the optimal design of the large-scale network, enhancing positioning service, the accurate timing and time synchronization, re‐ mote communication and the extension of the application are broken through. [ABSTRACT FROM AUTHOR]

Objectives: In surveying and cartography, solving geodetic latitude is a common reverse calcula⁃ tion by conformal latitude. Methods: Several different algorithms of reverse solution are studied, including iterative method, series expansion of solving geodetic latitude by difference of conformal latitude and direct algorithm of inverse solution of geodetic latitude with conformal latitude. The calculation formulas of the lat⁃ ter two algorithms are derived by Mathematica. The higher-order coefficient expansion formula are given. At the same time, problems in existing algorithms are analyzed. Results and Conclusions: Examples re⁃ sults of Lambert conic conformal projection show that the accuracy of the formula derived in this paper can reaches (1×10−7)″-(1×10−8)″. It fully meets the requirements of high precision in surveying and map projection. [ABSTRACT FROM AUTHOR]

Objectives: Aiming at the mixed observation data of multiple distribution forms, a expectation-maximum (EM) combined p-norm distributed model(EM_p) is established.Methods: Considering that the mixed number in the mixture model belongs to incomplete data, the EM algorithm is introduced to estimate the parameters of the mixture model and the p-model mixture model parameters are derived in detail. The estimated iteration formula and the corresponding iteration steps are given.The mixture Gaussian distribution data, Laplace distribution and Gaussian distribution mixture data, and the residual data of measured global positioning system(GPS) observations are used to verify the correctness and adaptability of the formula in this paper. Results and Conclusions: The results of the calculation examples show that, compared with the single probability distribution, the p-norm mixture model can accurately reflect the actual situation of the data distribution, and the model parameters estimated by the EM algorithm have higher accuracy. [ABSTRACT FROM AUTHOR]

Objectives: It is difficult to effectively evaluate and weaken the impact of observation environment change on data quality. To solve the problem, this paper studies a multi-point hemispherical grid model which can be applied to various satellite navigation systems.Methods: It integrates the observations of different global navigation satellite system (GNSS) satellite pairs in different observation periods to establish a global optimal multipath model. GNSS multipath error can be estimated effectively using multi-point hemispherical grid model (MHGM), image-based inverse of multipath effect and reflect the orientation of interference sources in the observation environment around stations. Results: To a certain extent the observation environment around stations can be modelled. The test under deliberate high multipath environment reveals that using MHGM significantly improved the root mean square error (RMSE) of the double-differenced carrier phase observation residuals in the period of fixed ambiguity, reducing the mean RMSE from 0.983 cm to 0.318 cm, a 67.7% improvement. In addition, the abnormal areas with large value of correction in the MHGM results is consistent with the direction of the baffle mounted at the corresponding stations. This model indicates multipath effects on GNSS carrier phase observations in different directions from the station. The test with International GNSS Service historical observations shows MHGM can effectively reflect the influence of changing multipath interference around stations on carrier phase observations, with an average improvement of 29.5% in the RMSE of residuals over the past 18 years. Conclusions: This model can be used to evaluate the changes in observation environments surrounding stations over time. It has potential application value to improve the accuracy and reliability of augmentation system products. [ABSTRACT FROM AUTHOR]

Objectives: Existing population spatialization methods mainly use administrative-unit-level data to train regression model, and transfer it to grid cell-level to achieve population allocation. However, the significant scale difference between the analytical units in training and estimation leads to the issues of crossscale model transfer. Meanwhile, only the attributes of current cell are considered in cell-level feature modeling, which causes the innate spatial association between cells to be eliminated and cells to be isolated. Methods: This paper proposes a novel population spatialization based on random forest by considering pixellevel attribute grading and spatial association (PAG-SA). In the cell-level feature modeling, we firstly construct the night light grading features embedded with building category constraints based on natural breaks, and count the grid proportion of each grading level at the administrative-unit-level as the training input to reduce the cross scale error; secondly, the influence and distance attenuation of neighborhood point of interests (POIs) upon the current cell is modelled by using kernel density estimation; thirdly, based on overlay analysis, the numbers of POIs in the contours of different building types are counted to improve the precision of feature modeling. Results: To verify the effectiveness of the proposed method, we selected Wuhan city as the experimental area and compared its spatialization accuracy with the datasets of WorldPop, GPW and PopulationGrid_China at street scale. The results show that the mean absolute error of PAG⁃SA is only 1/6-1/3 of the comparison datasets. In addition, the influence of feature composition, grid size and kernel density bandwidth on the accuracy is also discussed. Conclusions: By fusing multi source data and considering pixel⁃level attribute grading and spatial association, the proposed method PAG⁃SA is effective for achieving population spatialization in urban areas with finer grid sizes and higher accuracy. It can also provide references for spatialization applications of other geographic attributes that also face with scale mismatch issue in spatial regression modeling. [ABSTRACT FROM AUTHOR]

With the development of economy and urbanization in China, the issue of traffic congestion is increasingly prominent. Highways as the lifelines between cities are particularly vulnerable during the holidays. In order to manage highways more efficiently and regulate traffic more timely, it is necessary to detect congestion events on highways to realize the supervision of highway traffic. Using recognition data of highway path recognition system, transactions data of toll station, and GPS trajectory data of coach buses, touring buses and dangerous goods transport vehicles, this paper proposes a hierarchical congestion interval detection method which adopts fuzzy comprehensive evaluation algorithm to identify the traffic status of road sections. Taking the Changsha-Zhuzhou-Xiangtan urban agglomeration region of Hunan province as a case study, this paper uses the proposed method to detect and analyze traffic status of the experimental area in two weeks in February, 2018. [ABSTRACT FROM AUTHOR]

Coronavirus disease 2019(COVID-19) has broken out worldwide. Up to Apr.21,2020, more than 2.45 million confirmed cases have been diagnosed, and more than 0.17 million deaths have been reported. Based on the development process of China’s epidemic, this paper proposes an improved discrete time multi-stage time-delay dynamic model to extract the transmission characteristics of epidemic, the impact of prevention and control interventions (prevention and control intervention effect) and the impact of medical resource availability, and establishes an empirical transmission dynamics method of COVID 19 analysis. Among them, the experience extraction is based on the model and the epidemic data released by World Health Organization(WHO）， and realized by parameter inversion. Furthermore, by using the proposed method, this paper analyzes the epidemic stages in Italy, Spain, Germany and the United States, predicts the possible trend of epidemic situation in different countries under different measures, and gives suggestions on rapid control. Analysis results show that the China’s epidemic has been basically controlled, Spain, Germany and Italy have reached the peak, and the United States is in a rapid growth period. According to the empirical transfer dynamics method, Spain, Germany and Italy should continue to adhere to the current prevention and control intervention mode, and the United States should intensify the efforts of prevention and control and make the epidemic enter the controllable stage as soon as possible. [ABSTRACT FROM AUTHOR]

Current epidemic models mainly estimate the number of confirmed patients by fitting statistical data. Few studies consider the direct effect of fine-grained spatial crowd mobile interaction on the spatial-temporal diffusion features. A new method for estimating the spatial-temporal spread process of coronavirus disease 2019 (COVID-19) is proposed, incorporating spatial interaction features into epidemiological models. This paper also estimates the number of confirmed patients and spatial-temporal spread process of COVID-19 in Wuhan from December 2019 to March 2020. The results show that the method proposed in this paper can effectively estimate the daily traffic analysis zones (TAZs) where new confirmed patients appear, completely covering the TAZs with the epidemic announcements. And the TAZs with the epidemic announcements account for 72.7% of the estimated TAZs. The cumulative number of estimated confirmed patients agrees very well with the total number of officially announced confirmed patients after February 18, 2020, with a gap of approximately 5.6%, indirectly verifying the rationality of the previous estimation. The method proposed in this paper can effectively estimate the spread of infectious diseases under fine-grained spaces. It also has scientific significance in understanding the influence mechanism of the crowd interaction under finegrained spaces on the spatial-temporal spread of infectious diseases, and enhancing the macroscopically spatial interpretability of epidemiological models macroscopic. [ABSTRACT FROM AUTHOR]

Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aiming at the problem that Gauss projection in the line engineering project needs to be frequent⁃ ly strapped and has low precision when designing the plane construction drawing of the project, this paper proposes a large elliptical Gaussian projection of an elliptical line projecting from the ellipsoid elliptical line of the route for the new central meridian, and analyzes the parametric theoretical model of the elliptic ellip⁃ soid. Firstly, it derives the meridian arc length formula by using the naturalized latitude instead of the geo⁃ detic latitude as a parameter. Secondly, according to the quadratic curve invariant theory, linear algebra, calculus and other knowledge, it deduces the model of solving the basic geometric parameters of the large ellipse ellipsoid with the plane equation coefficient as the parameter. Furthermore, a direct conversion model of the geodetic coordinates between the base ellipsoid and the large ellipse ellipsoid is deduced. Finally, based on some actual engineering data, the correctness and superiority of the theoretical model deduced in this paper are verified to be popularized in long⁃term projects. [ABSTRACT FROM AUTHOR]

Geomagnetic matching technology can provide passive external resource of correction informa⁃ tion for underwater vehicle, which improves the long voyage navigation accuracy of inertial navigation sys⁃ tem. The filtering matching algorithm is the core technology in geomagnetic aided inertial navigation, which can effectively mitigate the influence from the uncertainty of geomagnetic observation noise. Based on track simulation data, the earth magnetic anomaly grid 2 (EMAG2) is selected as reference map in this paper. To properly model the observation noise of geomagnetic anomaly in unpredictable geomagnetic envi⁃ ronment and the error from measuring instruments, this paper proposes the matching algorithm of geomag⁃ netic anomaly filter based on residual errors. The observation noise variance is estimated adaptively through the residual⁃based adaptive estimation (RAE) filter. Meanwhile, the availability and robustness of the algo⁃ rithm are improved by combining the optimal filter selection criteria. The validation experiments of RAE fil⁃ ter are conducted in different maritime space of the South China Sea. It is shown that the drifting errors of inertial navigation system in longitude and latitude can be reduced based on the RAE filter. Moreover, the positioning accuracy and reliability of the aided navigation system can be improved significantly. In obvious geomagnetic fluctuating region under the simulation condition, position accuracy is raised to 0.751 53 n mile and 0.778 45 n mile respectively in latitude and longitude directions through RAE filter. [ABSTRACT FROM AUTHOR]

Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper aims at an analysis on the consistency of the top of atmosphere (TOA) reflectance among GF‐1 PMS2, GF‐2 PMS1 and Landsat‐8 operational land imager （OLI） sensor data based on two synchronous image pairs. The result shows that TOA reflectance of GF‐1 PMS2 and GF‐2 PMS1 sensors has a high degree of agreement. Nevertheless, this paper also finds that TOA reflectance of either GF‐1 PMS2 or GF‐2 PMS1 data is less consistent with that of Landsat‐8 OLI data, especially in the near-infrared band. In general, the rank of TOA reflectance in the blue, green and red bands of three sensors data is as follows: GF‐2 PMS1>GF‐1 PMS2>Landsat‐8 OLI, while the relationship in the near-infrared band is: Landsat‐8 OLI>GF‐1 PMS2> GF‐2 PMS1. The coversion models among the three sensors data were obtained through regression analysis. The validation shows that the conversion equations can significantly reduce the difference in the near-infrared band among the three sensors. It is also found that when the image to be converted has similar land cover types and proportions with the image on which the conversion model was developed, the conversion accuracy can be improve. [ABSTRACT FROM AUTHOR]

The water resources in the Tibetan Plateau have a profound impact on China’ s economic, social development and climate change. Based on gravity data from gravity recovery and climate experiment (GRACE) satellite , considering its filtering leakage error, this paper proposes the Forward ‐ Modeling method for quantitative estimation. In view of the glocial isostatic adjustment(GIA) effect, we first infer terrestrial water storage (TWS) changes in the Tibetan Plateau, and compare the results with the water‐global assessment and prognosis hydrology model(WGHM). Then we extract the time‐frequency spectrum of timeseries signals using short‐time Fourier transformation algorithm. In addition, we discuss the relationship between TWS and precipitation by combining with precipitation data from Global Presipitation Climatology Centre. The study finds that: (1) TWS shows obvious spatial differences after recovering leakage signal. In most of the period, TWS in the north and southeast is in large surplus, and TWS in the south and southwest is rapidly depleted. The spatial characteristics are basically consistent with the WGHM results. (2) The time‐frequency spectrum distribution of TWS is dominated by low‐frequency signals, and time‐series dynamic changes have obvious seasonal and periodic changes, with an annual amplitude of 7.5 cm. The increase rate of water storage in 2003―2004 was 3.89 cm/a. The loss rate in 2005―2010 was -0.31 cm/a. The rate of increase in 2011―2014 was 0.22 cm/a. (3) Precipitation is the main factor affecting the variation of TWS. In 2006 and 2009, precipitation was significantly lower, the water storage all decreased significantly. In 2010, there was heavy rainfall, the water storage increased significantly. The leakage error correction method and research results in this paper have important reference value for quantitative research on regional TWS varition. [ABSTRACT FROM AUTHOR]

The variation of the azimuth to Doppler center frequency of the terrain observation by progressive scans (TOPS) mode leads to the relative distortion of the phase of the interferogram. Therefore, high registration accuracy is required for interference processing. The Canadian Synthetic Aperture Radar Remote Sensing Satellite (RADARSAT‐2) TOPS mode image is less useful due to poor orbital accuracy and geometric registration accuracy, which makes the interference registration more complicated than it in sentinel SAR remote sensing (Sentinel‐1) satellite TOPS mode. In order to perform the interference processing of the TOPS mode data, this paper uses the cross‐correlation registration to correct the geometric registration results, and then uses the spectral diversity for the second geometric registration correction, and finally uses the enhanced spectral diversity to implement the final azimuth offset correction. Typically, the Doppler centroid estimation from satellite ephemeris parameters and focusing imaging parameters alone does not provide sufficient accuracy. Therefore, a phase increment method is proposed to optimize the Doppler center estimation and the estimated Doppler center is verified by the image bearing power spectrum in this paper. [ABSTRACT FROM AUTHOR]