Table of Content

19 June 2024, Volume 53 Issue 5

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Significant changes in the Qinghai-Tibet Plateau cryosphere

Data, methods and perspectives of optical stereo and bistatic SAR satellites for monitoring glacier thickness change in high-mountain Asia

Yushan ZHOU, Xin LI, Donghai ZHENG, Shanshan REN, Yingzheng WANG, Zhiwei LI

2024, 53(5):  779-800.  doi:10.11947/j.AGCS.2024.20230260

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Glacier thickness change is the most important indicator to assess the regional ice storage change, and glacier elevation measurements mainly based on optical stereo satellites and bistatic interferometric SAR satellites has become the primary means to assess the change of ice storage on a large scale. Firstly, this paper summarizes the main optical and radar satellite data and their measurement accuracy currently applied to glacierized areas in the high-mountain Asia. Then, we compile and summarize the methods of satellite monitoring of glacier thickness change (i.e. supervised-corrected DEM differencing method, automated-corrected DEM differencing method, time-series DEM parameterized regression method and time-series DEM non-parameterized regression method) and their applications. It is found that the current research suffers from some problems such as inaccurate elevation estimation in snow-covered glacier zones, inaccurate radar penetration depth estimation, and difficulty in monitoring seasonal glacier thickness variation, which leads to extremely limited understanding of some important local processes of glacier changes. Finally, this paper discusses potential research directions concerning the monitoring of glacier thickness changes, and suggests that both the use of archived satellite data and the future high spatial-temporal resolution observation programs and the fusion of multi-source altimetry data will help solve the problems currently faced.

Estimating glacier mass balance in the source region of the Yangtze River during 2000—2020 through InSAR

Jia LI, Zhiwei LI, Wenjie ZHONG, Yunyang GU, Long LI, Lei GUO, Juanjuan FENG

2024, 53(5):  801-812.  doi:10.11947/j.AGCS.2024.20230262

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This paper aims to estimate glacier mass balance in the source region of the Yangtze River, to investigate the factors that affect glacier mass balance, and to reveal the impacts of glacier mass changes on the runoff of the rivers. In particular, the InSAR technique and bistatic TerraSAR-X/TanDEM-X images were utilized to generate two DEMs that cover most of glaciers in the source region of the Yangtze River. The new DEMs were then differenced with SRTM DEM to obtain glacier thickness changes during 2000—2012 and 2000—2020, and a glacier mass density was used to converted the glacier thickness changes into glacier mass balance. The discrepancy between the derived glacier mass balance and the field measured glacier mass balance is only 0.03 m w.e.a^－1, indicating a high precision of the results. The glacier mass balance in source region of the Yangtze River during 2000—2012 and 2000—2020 were (－0.30±0.02) m w.e.a^－1 and (－0.45±0.04) m w.e.a^－1, respectively. Glacier melting during 2012—2020 apparently intensified relative to that during 2000—2012. Rise of summer temperature and decease of summer precipitation were deemed as the main cause of glacier mass loss. Moreover, the glacier melting rate decreases from the southeastern part to the northwestern part of the study area. Lower summer temperature, smaller temperature rising speed, higher glacier altitude, higher glacier accumulation area ratio, steeper glacier surface of the west area may account for this phenomenon. During 2000—2020, the glacier mass loss in the basin of the Tuotuo River contributed 4.4% of the runoff of the Tuotuo River, and those in the basins of the Tuotuo River and the Dangqu River contributed 2.5% of the runoff of the Tongtian River, indicating that glacier mass loss had slight impact on the runoff the upper reaches of the Yangtze River.

Joint inversion of GNSS and GRACE/GRACE-FO data for terrestrial water storage changes in Southwest China

Xinghai YANG, Linguo YUAN, Zhongshan JIANG, Miao TANG

2024, 53(5):  813-822.  doi:10.11947/j.AGCS.2024.20230221

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The global navigation satellite system (GNSS) and gravity recovery and climate experiment (GRACE), along with its follow-on mission (GRACE-FO) have revolutionized studies of terrestrial water storage changes (TWSC). However, TWSC estimates obtained from these two techniques exhibit different characteristics and accuracy in terms of temporal and spatial scales. Therefore, it is crucial to integrate these observations to obtain high-precision TWSC at a consistent scale. In this study, we designed a joint inversion model that combines GNSS and GRACE/GRACE-FO data for regional TWSC based on the GNSS inversion model (GNSS-IM). The summation operator was used for the Jet Propulsion Laboratory (JPL) GRACE/GRACE-FO Mascon data to construct constraints in the joint inversion model. The optimal model parameters were selected using the Akaike's Bayesian information criterion. To confirm the feasibility of the joint inversion model for estimating TWSC in Southwestern China, we conducted 1000 simulation experiments. The simulation results indicate that the joint inversion yields an average root mean square error of 10 mm, which is 47% lower than that of GNSS-IM. Subsequently, we applied the joint inversion to estimate the TWSC in Southwest China from January 2011 to June 2022, utilizing GNSS and JPL Mascon data. The comparison of the joint inversion results with the results of GNSS-IM, GRACE/GRACE-FO, and the high-resolution global land data assimilation system (GLDAS) shows that the TWSC annual amplitudes of the joint inversion exhibit the most consistent spatial distribution characteristics with those of GLDAS. It indicates that the joint inversion achieves better spatial resolution for TWSC compared to GNSS-IM and GRACE/GRACE-FO. Furthermore, we estimated the regional hydrological budget through the water balance equation and evaluated the uncertainty of the monthly rate of equivalent water height (d(EWH)/dt) of TWSC using the generalized three-cornered hat method. The results demonstrate that the uncertainty of d(EWH)/dt estimated by the joint inversion is 8 mm/month, which is 33%, 68%, and 62% lower than the results of GRACE/GRACE-FO, GNSS-IM, and the water balance equation, respectively. Our study indicates that the joint inversion approach improves the accuracy of TWSC compared to GNSS and GRACE/GRACE-FO, and provides more reliable data for water resources management and hydrology research.

Accuracy assessment of lake level and area measurement in the Qinghai-Tibet Plateau using simulated SWOT satellite data

Xiaoran HAN, Yinghai KE, Jinyuan YU, Mengjie ZHAO, Guoqing ZHANG

2024, 53(5):  823-834.  doi:10.11947/j.AGCS.2024.20230211

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As the “water tower of Asia”, the Qinghai-Tibet Plateau is densely covered with alpine lakes, accounting for about half of China 's lakes in both number and area. These lakes serve as critical indicators of climate and environmental conditions, highlighting the significance of monitoring their temporal variations in water level and volume. Launched in December 2022, the Surface Water and Ocean Topography (SWOT) mission will revolutionize our ability to observe global surface water dynamics, providing unprecedented temporal resolution and areal altimetry patterns. However, prior to the official release of SWOT satellite data to the scientific community, it is important to assess its performance and measurement accuracy. To achieve this goal, this study uses the SWOT simulator to facilitate simulated observations of water levels and areas of selected lakes on the Qinghai-Tibet Plateau. These simulated results are then combined with in-situ data to assess the SWOT satellite 's measurement accuracy in terms of temporal aliasing, altimetry errors, and area errors. The results show that the mean average percentage error of the temporal aliasing of the subsampled data is less than 4.1%, the average height measurement error is less than 3 cm, and the area error is less than 7% among these lakes. The development of this study has laid the foundation for the application of SWOT satellites on the lakes of the Qinghai-Tibet Plateau to better understand the response of future lake changes to climate change.

Remote sensing observation, retrieval, and analysis of temperature in the Qinghai-Tibet Plateau cryosphere

Ji ZHOU, Ziwei WANG, Lirong DING, Wenbin TANG, Wei WANG, Jin MA, Huiru JIANG, Shuang LIU, Tao ZHANG, Yingxu HOU

2024, 53(5):  835-847.  doi:10.11947/j.AGCS.2024.20230261

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The cryosphere serves as a sensitive indicator of climate change, while land surface temperature and near-surface air temperature are signals directly sensed by the indicator. They are key parameters for tracing the evolution history of the cryosphere, monitoring the current state, and simulating future changes. Due to a combination of adverse environmental conditions, complex terrain, low accessibility, and numerous unique underlying surfaces, ground-based temperature observations are challenging and sparsely distributed in the Qinghai-Tibet Plateau. Remote sensing has become an effective means of temperature acquisition. Focusing on land surface temperature and near-surface air temperature, this paper elucidates the related methodologies for ground-based observations, satellite, and unmanned aerial vehicle (UAV) remote sensing retrievals, and summarizes the research progress made by the academic community around the cryosphere of the Qinghai-Tibet Plateau. Furthermore, this paper discusses the applications of remote sensing temperature parameters in frozen ground, lake ice, glaciers, and other aspects of the Qinghai-Tibet Plateau. Challenges in temperature remote sensing acquisition in the Qinghai-Tibet Plateau cryosphere are summarized, and future research directions worthy of emphasis are explored.

Quantitative study on driving factors of land surface temperature trends on the Qinghai-Tibet Plateau from 2003 to 2020 based on partial correlation analysis

Mengjiao YANG, Wei ZHAO, Qiqi ZHAN, Ya ZHANG, Xiaorong MENG, Junfei CAI, Yujia YANG

2024, 53(5):  848-859.  doi:10.11947/j.AGCS.2024.20230206

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As a key parameter of land-atmosphere interaction, land surface temperature (LST) plays an important role in the surface water-heat cycle and can accurately characterize changes in the surface thermal environment. The Qinghai-Tibet Plateau has the largest cryosphere except for the polar regions, which has a profound impact on the regional and global climate system and ecological economy. As the region with the most significant climate change, an in-depth understanding of the driving factors of LST dynamic changes in the cryosphere of the Qinghai-Tibet Plateau can provide important scientific support for an accurate understanding of the changing laws and driving mechanisms of the cryosphere thermal environment of the Qinghai-Tibet Plateau. Based on the mean annual surface temperature (MAST) extracted from the annual temperature cycle model, this study used partial correlation analysis to analyze the relationship between the MASTs and cloud amount, vegetation coverage, snow cover, precipitation, and air temperature from 2003 to 2020 and revealed the main driving factors of the change of MAST in different regions of the Qinghai-Tibet Plateau. The results show that the four driving factors of cloud amount, vegetation coverage, snow cover, and precipitation mainly have negative partial correlations during the daytime while positive partial correlations during the nighttime, and there are positive partial correlations for air temperature during both the daytime and nighttime. For the dominant factors of MAST dynamic changes on the Qinghai-Tibet Plateau, there are significant differences in the dominant factors of MAST in different regions of the Qinghai-Tibet Plateau. The MAST dynamic changes on the Qinghai-Tibet Plateau during the daytime are mainly affected by cloud amount with a main negative partial correlation (the dominant change area accounts for 38.17%), and the affected area is concentrated on the northwest and the west of the Qinghai-Tibet Plateau. The overall MAST changes on the Qinghai-Tibet Plateau at nighttime are mainly dominated by air temperature with a positive partial correlation (the dominant change area exceeds 48%), reflecting that the influence of climate warming on MAST at nighttime is stronger than that during the daytime. This study can provide a scientific reference for the protection and sustainable development of the cryosphere on the Qinghai-Tibet Plateau under the background of climate change.

Spatial scale effects of grassland phenology on the Qinghai-Tibet Plateau

Dujuan MA, Jiangliu XIE, Rui CHEN, Xinyu YAN, Gaofei YIN

2024, 53(5):  860-868.  doi:10.11947/j.AGCS.2024.20230256

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Accurate high-altitude vegetation phenology remote sensing products are fundamental data for maintaining ecological balance, accurately reflecting surface energy balance, and stabilizing the cryosphere. However, currently used remote sensing data for phenology extraction have diverse spatial resolutions, and phenology extracted based on different spatial scales may exhibit scale effects, which have not received widespread attention. In this study, utilizing Sentinel-2 data with a spatial resolution of 10 m, MODIS data with spatial resolutions of 500 and 5600 m, and employing the NDGI vegetation index, phenology products with corresponding spatial resolutions for the Qinghai-Tibet Plateau in 2022 were extracted on the Google Earth Engine (GEE) cloud platform. The study explored the differences in phenology at different spatial resolutions, quantitatively analyzed the scale effects of phenology products, and elucidated their variations with terrain complexity. The research revealed that, compared to high spatial resolution remote sensing products (10 m), there is a noticeable lag phenomenon in the spring phenology of coarser spatial resolution (500 and 5600 m). When detecting grassland phenology using remote sensing products with different spatial resolutions, scale effects are generally present, with the scale effect of autumn phenology being smaller than that of spring phenology. Additionally, the scale effect of vegetation phenology is influenced by terrain and increases with the complexity of terrain.

Geodesy and Navigation

BDS real-time 100 picosecond level single difference time and frequency synchronization method

Chuang SHI, Wei SONG, Fu ZHENG, Haoyuan WANG, Yuzhuo WANG, Aimin ZHANG, Weiming TANG

2024, 53(5):  869-878.  doi:10.11947/j.AGCS.2024.20230353

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High precise time-frequency transfer and time synchronization services have become a research focus in GNSS applications. Scholars have conducted numerous studies on time-frequency synchronization models, algorithms and related applications. We propose adifferential precise time transfer model based on carrier phase observations, and establish a BeiDou navigation satellite system real-time 100 picosecond level differential time and frequency synchronization system. With the time transfer results of the fiber optic links as reference, differential precise time and frequency synchronization performance is validated. the standard deviation of the BDS real-time pulse per second results is better than 100 ps. What's more, the time deviation of the time link within 7 days is better than 70 ps. In terms of frequency stability, modified Allan deviation of 10⁴ seconds can reach the level of 10^－15, and the long-term frequency stability reaches the level of 10^－16. Additionally, the frequency stability of BDS is comparable to that of GPS, which is of valuable significance for further expanding the application of BDS in the time and frequency community.

Schmidt Kalman filter in autonomous orbit determination of navigation satellites

Xiaoyong SONG, Yuanxi YANG, Yue MAO, Rengui RUAN, Long WANG

2024, 53(5):  879-888.  doi:10.11947/j.AGCS.2024.20230228

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To further improve the accuracy of autonomous orbit determination (AOD) of BDS navigation satellites with the equivalent observation Kalman filter, the Schmidt Kalman filter algorithm is applied, considering the cross covariance information between two correlated satellite states of the inter-satellite link observation. The formula for the measurement update and time update of Schmidt Kalman filter according to the observation one by one is deduced, and the square root filtering is also used to ensure the positive definite of the covariance matrix of state variable. The simulation and observed data test result of autonomous orbit determination shows that the Schmidt Kalman filter algorithm can perceptibly improve the AOD accuracy compared with the equivalent observation Kalman filter.

A global vertical correction model of PWV considering the spatial-temporal variation of decay coefficient

Chunhua JIANG, Xiang GAO, Shuaimin WANG, Huizhong ZHU, Shaoni CHEN, Guangsheng LIU

2024, 53(5):  889-899.  doi:10.11947/j.AGCS.2024.20230148

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Precipitable water vapor (PWV) plays an important role in multi-scale climate change and atmospheric physical processes. To improve the accuracy of vertical correction of PWV and further extend the spatial applications of multi-source PWV products, we propose a global stratification grid model named as GPWVCS based on ERA5 reanalysis data from 2010 to 2019, considering the spatial-temporal variation of PWV vertical decay coefficient. And the accuracy and application of the new model on a global scale are evaluated using ERA5 and radiosonde derived-PWV. The results show that compared with the empirical model and the unstratified GPWVC model, the GPWVCS model effectively improves the vertical correction accuracy of PWV. Taking ERA5 PWV as reference, the RMS of PWV adjusted by GPWVCS model in each region over the globe is less than 1.9 mm. Taking radiosonde data profiles as reference, the annual mean RMS values of GPWVCS model in the tropical, temperate, frigid zone and globe are 2.24, 1.29, 0.44 and 1.44 mm, respectively, which achieve accuracy improvements of 34.6%, 14.1%, 10.9% and 21.4% compared with the empirical model, and they are corresponding to 6.4%, 5.8%, 9.4% and 6.0% improvement against the GPWVC model. The stratification algorithm of GPWVCS model greatly weakens the impact of the PWV accumulated error which is attributed to the exponential extrapolation. All three models with horizontal-resolutions of 1°×1°, 2°×2° and 5°×5° developed in this study can significantly improve the global performance of vertical correction for PWV in terms of different height differences, and users can choose the best model according to the requirements of computational efficiency and accuracy.

Band-limited SRBF quadratic approximation method for local gravity fields in complex regions

Zhiwei MA, Shaofeng BIAN, Ruyi XU, Yongbing CHEN

2024, 53(5):  900-916.  doi:10.11947/j.AGCS.2024.20230132

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Utilizing the SRBF-based two-step cumulative approximation method, this study conducted a detailed numerical analysis and validation for the construction of a local gravity field model in complex areas. First, data from the global gravity field model were combined with airborne gravity data to construct the initial SRBF-based gravity field model for the study area (the first gravity field approximation based on band-limited SRBFs). When compared to the airborne-only gravity field model, the standard deviation of geoid height discrepancies between the initial gravity field model and GPS/leveling data decreased by approximately 0.022 m. This suggests the effectiveness of merging GGM and airborne gravity data for initial modeling. Subsequently, after removing the effects of the reference gravity field model, the initial gravity field model and the residual terrain model from the terrestrial and airborne gravity data, a secondary SRBF-based modeling process was conducted (the second gravity field approximation based on band-limited SRBFs). Compared to the one-step SRBF model, the two-step approach yielded reductions of 0.036 m and 0.024 m in terms of STD and RMS, respectively, highlighting the superiority of the SRBF-based two-step cumulative approximation method. Moreover, the study area features a complex mountainous terrain, which can serve as a reference for constructing gravity field model in similar complex regions.

Landslide displacement weighted inverse analysis and monitoring and warning method under the combined action of rainfall and reservoir water level

Wei YUAN, Xiaolei JI, Dongpo WANG, Kaige GUAN, Zihao PEI, Huiya ZHONG, Jia TANG, Ruifeng SUN, Wei WANG, Hemin ZHENG, Shuaijie GUO, Hongxu LI

2024, 53(5):  917-932.  doi:10.11947/j.AGCS.2024.20230009

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Rainfall and reservoir water level variation are the main external factors that induce continuous deformation and even instability of large reservoir bank landslide. Aiming at the deformation characteristics of landslide under the combined action of the above two factors, a four-step landslide monitoring and warning method based on multi-source heterogeneous data is proposed in this study. In this method, the trend term displacement is used to invert mechanical parameters, which effectively avoids the influence of external factors such as rainfall and reservoir water level change on the inversion results. Meanwhile, the entropy weight is used to construct the inversion objective function, which takes into account the influence of monitoring points at different locations on the inversion results. In addition, the influence of the geological conditions of the slope itself and the slope structure on the monitoring and early warning is considered. Besides, considering the influence of geological conditions and slope structure on monitoring and warning, a warning model with geological and mechanical basis was established by comprehensive use of safety factor and comprehensive deformation rate. Finally, mechanical parameter inversion and monitoring and early warning are carried out for Donglingxin landslide of Sanbanxi hydropower station, Guizhou province by virtue of the proposed method in this study. The results show that the safety factor of the landslide fluctuates between 1.25 and 1.70 during the whole monitoring period, and the overall state is declining. Based on the safety factor, it is still in a stable state. The comprehensive deformation rate presents an upward and downward fluctuation trend, which is highly correlated with the variation law of the safety factor. Both of them can represent the evolution process of the stability of the landslide under the combined action of rainfall and reservoir water level. The comprehensive deformation rate of the current monitoring moment point is 0.059 9. According to the hierarchical warning model, the landslide is currently in the stable deformation stage (level I warning), which is consistent with the judgment result of the safety factor.

The characteristic of the Yadong-Gulu faults motion constraints by InSAR timeseries and GNSS observations

Canghai ZHOU, Zhen TIAN, Zhen SHI, Hayinaer TUOKAN

2024, 53(5):  933-945.  doi:10.11947/j.AGCS.2024.20230480

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As the largest and most active extension fault in the southeast of the Qinghai-Tibet Plateau since Cenozoic Era, the Yadong-Gulu faults play an important role in regulating and transferring the tectonic deformation and material migration in the Qinghai-Tibet Plateau. However, due to the lack of geodetic observations, the estimates on the overall motion characteristics of the Yadong-Gulu fault is insufficient. Therefore, in this paper, we collected and processed the Sentinel data from October 2017 to April 2022 around the Yadong-Gulu fault, combined with the GNSS data to estimate and merge the crustal deformation in the different reference frames, and obtained the high-precision and resolution interseismic deformation covering the entire Yadong-Gulu fault region. Based on the elastic micro-block model, the present activity characteristics of the Yadong-Gulu fault are determined: the fault mainly dips to the east, with an optimum dip angle of 68°. The extensional slip rate is close to 2～6 mm/a, and gradually increases from south to north. In addition, the locking depth of the middle and north segments of the fault is about 14 km. However, the southern segment may be affected by the main Himalayan thrust, resulting in a shallow locking area (only 4 km). Finally, based on the slip deficit rate on the fault and the historical earthquakes, we infer that the future earthquake risk is higher in the northern segment, which provides an important reference for the regional geological hazard assessment.

Photogrammetry and Remote Sensing

Parallel SfM-based 3D reconstruction for unordered UAV images

San JIANG, Yichen MA, Qingquan LI, Wanshou JIANG, Bingxuan GUO, Lizhe WANG

2024, 53(5):  946-958.  doi:10.11947/j.AGCS.2024.20230335

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Efficient incremental structure from motion (ISfM) has become the core technique for (unmanned aerial vehicle, UAV) image orientation. However, the characteristics of large volume, high overlap, and high resolution cause the deficiency in match pair retrieval and the accumulated error and low efficiency in bundle adjustment (BA) optimization, which degenerate its performance for large-scale scenes. This study proposes a parallel SfM for UAV images via global descriptors and graph-based indexing. On the one hand, to cope with the deficiency caused by a large number of local descriptors and the large size of a codebook, an efficient match pair retrieval is designed via the global descriptor and graph-based indexing, which could dramatically accelerate feature matching; on the other hand, to address the deficiency of correspondence searching and low accuracy of transformation estimation in parallel SfM, this study designs an efficient cluster merging algorithm based on the on-demand correspondence graph and bi-directional reprojection error, which achieves efficient and accurate parallel SfM. The proposed algorithm is verified by using three UAV datasets, and the experimental results demonstrate that the proposed method can increase match pair retrieval with speedup ratios ranging from 36 to 108, and dramatically improves the SfM efficiency with the speedup ratio better than 30 and with the comparative accuracy. The accuracy of relative and absolute orientation is comparative to that of traditional methods.

Large-scale TanDEM-X InSAR sub-canopy topography inversion under insufficient observation information

Jun ZHU, Wei PENG, Haiqiang FU, Man OU, Shancheng LEI, Shiping ZHANG

2024, 53(5):  959-966.  doi:10.11947/j.AGCS.2024.20230004

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The TerraSAR/TanDEM-X InSAR system is currently one of the most important global mapping satellite systems, the data acquired by this system is mainly single-baseline, single-polarized SAR data. Restricted by insufficient observation information, vegetation, and surface scattering information cannot be directly separated from the data, which makes it hard to apply the system to the large-scale, high-precision inversion of terrain under forest. Therefore, this article proposes a method for large-scale terrain inversion under forest using single/dual baseline observations. The core concept of this method is as follows: for overlapping zones (dual baseline observation), the RVoG model is used to estimate the terrain under forest and the forest height; for non-overlapping zones (single baseline observation), with the estimated tree height of the overlapping zone as the prior information, a simplified RVoG model (C-SINC) is used to estimate the terrain under forest. The new method was analyzed and verified in the Teruel experimental zone of Spain. Comparing the results with LiDAR DEM, the RMSE of sub-canopy topography acquired by this method is 5.98 m, which is 20% higher in precision than the RMSE of 7.43 m obtained by InSAR DEM. For large-scale areas, the new method provides a reference for the application of TanDEM-X to estimate the sub-canopy Topography.

Cartography and Geoinformation

Elements and organization of narrative maps: a element-structure-scene architecture based on the video game perspective

Shen YING, Yajie XU, Yu LI

2024, 53(5):  967-980.  doi:10.11947/j.AGCS.2024.20230435

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The object space of maps has expanded from the binary space to the ternary space in the information and communication technology (ICT) Era. The expression scope of traditional cartography, which is composed of map projection, map generalization, and map symbol system, has been broken by the emergence of the information space. Therefore, the classic theoretical framework can no longer meet the cartographic needs brought about by the metaverse, the fusion of virtual and reality, and the fusion of human, machine and object. To address this problem, this paper discusses the organization of narrative maps with the framework of “element-structure-scene”. Narrative elements are the foundation for constructing narrative maps, narrative structures provide organizational forms for narrative elements, and narrative scenes provide carriers for presenting the narrative elements and narrative structures. Considering the natural narrative nature of geographic environment games, this paper exemplifies the applications of narrative “element-structure-scene” from the perspective of game maps, aiming to provide a theoretical basis for the applications and practices of narrative maps within the ICT context.

Summary of PhD Thesis

Indoor semantic segmentation based on global energy optimization and anchor-based graph method from 3D point clouds

Fei SU

2024, 53(5):  981-981.  doi:10.11947/j.AGCS.2024.20230099

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Global marine gravity anomaly model derived from multi-band altimeter data and shipborne gravity data

Chengcheng ZHU

2024, 53(5):  982-982.  doi:10.11947/j.AGCS.2024.20230102

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Research on optimization problem of smartphone indoor hybrid positioning using Wi-Fi RTT and PDR

Hongji CAO

2024, 53(5):  983-983.  doi:10.11947/j.AGCS.2024.20230114

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Research on the perception methods for people's spatial-temporal mobility in the city from the perspective of geographic flow

Jing LI

2024, 53(5):  984-984.  doi:10.11947/j.AGCS.2024.20230144

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