{"results":[{"id":"doaj_10.1016/j.srs.2025.100266","title":"Investigating seasonal velocity variations of selected glaciers in high mountain asia","authors":[{"name":"Francesca Baldacchino"},{"name":"Whyjay Zheng"},{"name":"Kunpeng Wu"},{"name":"Vassiliy Kapitsa"},{"name":"Alexandr Yegorov"},{"name":"Tobias Bolch"}],"abstract":"Glacier velocity is a sensitive indicator of mass balance and is key to understanding how glaciers respond to climate change. Monitoring glacier velocity at high temporal resolutions enables a better understanding of the drivers of glacier dynamics. Previous studies have found that the glaciers in High Mountain Asia (HMA) tend to slow down concomitant to losing mass at an accelerating rate on decadal timescales. However, few studies have explored seasonal variations in glacier velocities and have typically focused on large, fast-flowing glaciers. We select one debris-covered glacier, and four clean-ice glaciers in HMA. Sentinel-1 and -2 images are used to calculate the glacial velocities using the feature tracking module provided by the Cryosphere And Remote Sensing Toolkit (CARST). We develop a novel, regularised linear inverse model to extract the seasonally resolved glacial velocity time series (6-day intervals) with rigorous uncertainty estimates. Our results show that three of the five glaciers have strong seasonal signals in velocities, with faster velocities in spring and/or summer compared to winter. We also find an up-glacier propagation of the late spring and/or summer accelera-tions and a down-glacier propagation of the autumn accelerations. We suggest that changes in the subglacial hydrology efficiency drive the observed seasonal variations in velocities. We also highlight that icefalls may alter the glacier flow response by blocking the development of subglacial drainage channels and thus the seasonal propagation of velocities. Our methodol-ogy enables us to successfully extract seasonal signals in glaciers that flow slowly and provide a further understanding of glacier dynamics.","source":"DOAJ","year":2025,"language":"","subjects":["Physical geography","Science"],"doi":"10.1016/j.srs.2025.100266","url":"http://www.sciencedirect.com/science/article/pii/S2666017225000720","is_open_access":true,"published_at":"","score":69},{"id":"doaj_https://doi.org/10.47960/2232-9080.2025.29.15.73","title":"GEOCHEMICAL CHARACTERISATION OF SOIL USING XRF: IMPLICATION FOR GEOTECHNICAL PROPERTIES","authors":[{"name":"David Idiata"},{"name":"Ngozi Kayode - Ojo"},{"name":"Ehizonomhen Okonofua"}],"abstract":"This study investigates the geochemical and geotechnical properties of soils from Uwelu, Benin City, Nigeria (6.3861°N, 5.5827°E, 107 m altitude), to assess their engineering relevance. Samples from two sites underwent tests including specific gravity, sieve analysis, Atterberg limits, compaction, and California Bearing Ratio (CBR), following ASTM and AASHTO standards. X-ray fluorescence (XRF) was used to determine the presence of major oxides and trace elements. The soils, classified as A-2-4 and A-2-6 by AASHTO, had specific gravities of 2.55 and 2.54. The optimum moisture content was 10%, with Maximum Dry Densities (MDD) of 2.01 and 2.06 g/cm³. CBR results showed higher strength in unsoaked samples (20.11%, 6.38%) than soaked ones (9.69%, 3.24%). SiO₂ dominated the geochemistry (57.33%, 48.36%), with notable Al₂O₃ and Fe₂O₃. The findings emphasize the value of integrating geochemical and geotechnical analyses in construction.","source":"DOAJ","year":2025,"language":"","subjects":["Engineering (General). Civil engineering (General)"],"doi":"https://doi.org/10.47960/2232-9080.2025.29.15.73","url":"https://e-zbornik.gf.sum.ba/en/archive-en/e-zbornik-no-29/no-29-paper-6","is_open_access":true,"published_at":"","score":69},{"id":"doaj_10.1080/10095020.2024.2328100","title":"On China’s earth observation system: mission, vision and application","authors":[{"name":"Deren Li"},{"name":"Mi Wang"},{"name":"Haonan Guo"},{"name":"Wenjie Jin"}],"abstract":"China’s Earth Observation(EO) System has undergone significant development since the 1970s, as China has dedicated substantial efforts to advancing remote sensing technology. With fifty years of development, China has successfully narrowed the remote sensing technology gap with foreign countries through collaborative endeavors of the government and enterprises. At present, China has constructed a comprehensive EO system that has been proven indispensable for driving economic growth and facilitating sustainable development. This paper provides an overview of the development, missions, andapplications of China’s EO system, while also exploring future directions and technical trends of China’s EO system.","source":"DOAJ","year":2025,"language":"","subjects":["Mathematical geography. Cartography","Geodesy"],"doi":"10.1080/10095020.2024.2328100","url":"https://www.tandfonline.com/doi/10.1080/10095020.2024.2328100","is_open_access":true,"published_at":"","score":69},{"id":"doaj_10.1016/j.eng.2024.09.001","title":"A Review on Modeling Environmental Loading Effects and Their Contributions to Nonlinear Variations of Global Navigation Satellite System Coordinate Time Series","authors":[{"name":"Zhao Li"},{"name":"Weiping Jiang"},{"name":"Tonie van Dam"},{"name":"Xiaowei Zou"},{"name":"Qusen Chen"},{"name":"Hua Chen"}],"abstract":"Nonlinear variations in the coordinate time series of global navigation satellite system (GNSS) reference stations are strongly correlated with surface displacements caused by environmental loading effects, including atmospheric, hydrological, and nontidal ocean loading. Continuous improvements in the accuracy of surface mass loading products, performance of Earth models, and precise data-processing technologies have significantly advanced research on the effects of environmental loading on nonlinear variations in GNSS coordinate time series. However, owing to theoretical limitations, the lack of high spatiotemporal resolution surface mass observations, and the coupling of GNSS technology-related systematic errors, environmental loading and nonlinear GNSS reference station displacements remain inconsistent. The applicability and capability of these loading products across different regions also require further evaluation. This paper outlines methods for modeling environmental loading, surface mass loading products, and service organizations. In addition, it summarizes recent advances in applying environmental loading to address nonlinear variations in global and regional GNSS coordinate time series. Moreover, the scientific questions of existing studies are summarized, and insights into future research directions are provided. The complex nonlinear motion of reference stations is a major factor limiting the accuracy of the current terrestrial reference frame. Further refining the environmental load modeling method, establishing a surface mass distribution model with high spatiotemporal resolution and reliability, exploring other environmental load factors such as ice sheet and artificial mass-change effects, and developing an optimal data-processing model and strategy for reprocessing global reference station data consistently could contribute to the development of a millimeter-level nonlinear motion model for GNSS reference stations with actual physical significance and provide theoretical support for establishing a terrestrial reference frame with 1 mm accuracy by 2050.","source":"DOAJ","year":2025,"language":"","subjects":["Engineering (General). Civil engineering (General)"],"doi":"10.1016/j.eng.2024.09.001","url":"http://www.sciencedirect.com/science/article/pii/S2095809924005575","is_open_access":true,"published_at":"","score":69},{"id":"doaj_10.1109/JSTARS.2024.3470222","title":"Snow Depth Retrieval Using Detrended SNR From GNSS-R With Bidirectional GRU","authors":[{"name":"Wei Liu"},{"name":"Zihui Lin"},{"name":"Yuan Hu"},{"name":"Aodong Tian"},{"name":"Xintai Yuan"},{"name":"Jens Wickert"}],"abstract":"Snow depth monitoring is crucial for hydrology, climate research, and avalanche prediction. While traditional global navigation satellite system (GNSS) reflectometer methods offer cost-effective snow thickness retrieval, they suffer from poor accuracy and robustness, especially in complex terrains and extreme weather. This study proposes an innovative snow depth retrieval technique employing a time-series recurrent neural network with bidirectional gated recurrent units (Bi-GRUs). Unlike traditional methods using signal-to-noise ratio (SNR) features, our algorithm utilizes the detrended SNR as Bi-GRU input, aiming to enhance accuracy, particularly in low snow depths and complex terrains. SNR observations from GPS L1 carriers at stations P351 and AB33 were analyzed. The Bi-GRU algorithm demonstrated high consistency with true snow depths at station P351 (coefficient of determination: 0.9766), with the root-mean-square error (RMSE) and the mean absolute error (MAE) of 9.1559 and 6.4185 cm, respectively. Compared to traditional methods, the Bi-GRU model improved the RMSE by 30.9\u0026#x0025; and the MAE by 44.5\u0026#x0025;. At station AB33, where snow depth variations were significant, accuracy improvements of 65.6\u0026#x0025; (RMSE: 7.4905 cm) and 63.2\u0026#x0025; (MAE: 5.6074 cm) were observed. In addition, the Bi-GRU model exhibited greater robustness compared to long short-term memory. These findings highlight the efficacy of the Bi-GRU-based approach, suggesting its superiority and broader applicability.","source":"DOAJ","year":2024,"language":"","subjects":["Ocean engineering","Geophysics. Cosmic physics"],"doi":"10.1109/JSTARS.2024.3470222","url":"https://ieeexplore.ieee.org/document/10697422/","is_open_access":true,"published_at":"","score":68},{"id":"doaj_10.1186/s40623-024-02004-9","title":"Data assimilation for fault slip monitoring and short-term prediction of spatio-temporal evolution of slow slip events: application to the 2010 long-term slow slip event in the Bungo Channel, Japan","authors":[{"name":"Masayuki Kano"},{"name":"Yusuke Tanaka"},{"name":"Daisuke Sato"},{"name":"Takeshi Iinuma"},{"name":"Takane Hori"}],"abstract":"Abstract Monitoring and predicting fault slip behaviors in subduction zones is essential for understanding earthquake cycles and assessing future earthquake potential. We developed a data assimilation method for fault slip monitoring and the short-term prediction of slow slip events, and applied to the 2010 Bungo Channel slow slip event in southwest Japan. The observed geodetic data were quantitatively explained using a physics-based model with data assimilation. We investigated short-term predictability by assimilating observation data within limited periods. Without prior constraints on fault slip style, observations solely during slip acceleration predicted the occurrence of a fast slip; however, the inclusion of slip deceleration data successfully predicted a slow transient slip. With prior constraints to exclude unstable slip, the assimilation of data after slow slip event occurrence also predicted a slow transient slip. This study provides a tool using data assimilation for fault slip monitoring and prediction based on real observation data. Graphical Abstract","source":"DOAJ","year":2024,"language":"","subjects":["Geography. Anthropology. Recreation","Geodesy","Geology"],"doi":"10.1186/s40623-024-02004-9","url":"https://doi.org/10.1186/s40623-024-02004-9","is_open_access":true,"published_at":"","score":68},{"id":"doaj_10.1186/s43020-022-00081-3","title":"Multi-GNSS products and services at iGMAS Wuhan Innovation Application Center: strategy and evaluation","authors":[{"name":"Xingxing Li"},{"name":"Qingyun Wang"},{"name":"Jiaqi Wu"},{"name":"Yongqiang Yuan"},{"name":"Yun Xiong"},{"name":"Xuewen Gong"},{"name":"Zhilu Wu"}],"abstract":"Abstract Over the past years the International Global Navigation Satellite System (GNSS) Monitoring and Assessment System (iGMAS) Wuhan Innovation Application Center (IAC) dedicated to exploring the potential of multi-GNSS signals and providing a set of products and services. This contribution summarizes the strategies, achievements, and innovations of multi-GNSS orbit/clock/bias determination in iGMAS Wuhan IAC. Both the precise products and Real-Time Services (RTS) are evaluated and discussed. The precise orbit and clock products have comparable accuracy with the precise products of the International GNSS Service (IGS) and iGMAS. The multi-frequency code and phase bias products for Global Positioning System (GPS), BeiDou Navigation Satellite System (BDS), Galileo navigation satellite system (Galileo), and GLObal NAvigation Satellite System (GLONASS) are provided to support multi-GNSS and multi-frequency Precise Point Positioning (PPP) Ambiguity Resolution (AR). Compared with dual-frequency PPP AR, the time to first fix of triple-frequency solution is improved by 30%. For RTS, the proposed orbit prediction strategy improves the three dimensional accuracy of predicted orbit by 1 cm. The multi-thread strategy and high-performance matrix library are employed to accelerate the real-time orbit and clock determination. The results with respect to the IGS precise products show the high accuracy of RTS orbits and clocks, 4–9 cm and 0.1–0.2 ns, respectively. Using real-time satellite corrections, real-time PPP solutions achieve satisfactory performance with horizontal and vertical positioning errors within 2 and 4 cm, respectively, and convergence time of 16.97 min.","source":"DOAJ","year":2022,"language":"","subjects":["Technology (General)"],"doi":"10.1186/s43020-022-00081-3","url":"https://doi.org/10.1186/s43020-022-00081-3","is_open_access":true,"published_at":"","score":66},{"id":"doaj_10.1016/j.ejrs.2022.08.002","title":"Impacts of land-use changes and landholding fragmentation on crop water demand and drought in Wadi El-Farigh, New Delta project, Egypt","authors":[{"name":"Mohamed M. Elsharkawy"},{"name":"Mohsen Nabil"},{"name":"Eslam Farg"},{"name":"Sayed M. Arafat"}],"abstract":"Despite Egypt’s limited water resources, more lands in the western desert of the Nile Delta are currently being reclaimed to increase the agricultural area to feed its fast-growing population and provide jobs for new generations. These reclaimed lands are prone to drought since they are located in arid regions with limited water resources for irrigation. Moreover, a high rate of landholdings fragmentation was observed with the migration of large numbers of new farmers to the newly reclaimed areas. Hence, the current work uses remote sensing data to investigate the impacts of landholdings fragmentation and land-use changes on irrigation water demand and drought propagation in two selected sites in Wadi El-Farigh area, one of the newly reclaimed valleys in the western desert of Egypt. To achieve that goal, high-resolution satellite images were used to quantify the land-use changes and patterns. The Surface Energy Balance System (SEBS) was used to estimate the actual evapotranspiration (ETa) from 2010 to 2020. Standardized Precipitation Index (SPI) and Evaporative Stress Index (ESI) were used to monitor drought. Results indicated a large transformation of seasonal herbaceous crops to tree-fruit crops in the two study sites. However, landholding fragmentation caused a reduction in the total cultivated area and thus the accumulated water consumption over one study site. Although the accumulated ETa decreased following the decline in the total cultivated area, the ETa rate per hectare increased by 18.4% and 19.6% for trees and herbaceous crops, respectively, reflecting the negative impact of climate change. ESI and SPI time series confirms that the area became extremely dry, particularly after 2017. In conclusion, land use and climate change increased crop water demand, while landholding fragmentation led to cropland loss. Hence, more policies for land protection and adaptation strategies to climate change are essentially needed.","source":"DOAJ","year":2022,"language":"","subjects":["Geodesy"],"doi":"10.1016/j.ejrs.2022.08.002","url":"http://www.sciencedirect.com/science/article/pii/S1110982322000734","is_open_access":true,"published_at":"","score":66},{"id":"doaj_10.19975/j.dqyxx.2022-029","title":"Advances and perspectives for receiver function imaging of the Earth's internal discontinuities and velocity structures","authors":[{"name":"Ling Chen"},{"name":"Xu Wang"},{"name":"Xin Wang"},{"name":"Zigen Wei"},{"name":"Jianyong Zhang"}],"abstract":"Studying the structures, properties and origins of the Earth's internal discontinuities is an important part in the efforts to understand the physical and chemical properties of the layered Earth, as well as to explore the dynamic processes and driving mechanisms of plate tectonics and the whole Earth system. Receiver function imaging is a well-known and widely-adopted seismological method in extracting the structural information of the Earth's internal discontinuities, and has become an indispensable tool to investigate the layering in structure and composition, and the thermal states and deformation behaviors of the crust and upper mantle, lithosphere-asthenosphere, mantle transition zone, and even shallow part of the lower mantle in the deep Earth. Since the receiver function method was proposed about half a century ago, great progress has been made in both methodology and application, targeting to subsurface structures of various spatial scales and from one- to three-dimension. In particular, with more and more seismic arrays being deployed in global and regional scales, and the continuous advancement of computing power and imaging theory during the last two decades, receiver function imaging has only become more powerful to constrain the subsurface structures. In this paper, we first briefly review the development history of the receiver function method. After introducing the basic principles involved, we then outline the major progress made during the last two decades in both methodology and application of this method, including but not limited to receiver function construction and forward modeling, receiver functions analysis for complex media or detailed discontinuity structures (e.g., anisotropy, dipping structures, irregular topography, sharpness of discontinuities), ray and wave-equation based receiver function migration in imaging crustal and upper mantle discontinuities, velocity inversion of receiver functions as well as its combination with other types of data. We focus mainly on the following three aspects: deconvolution techniques to construct receiver functions, imaging of discontinuity structures and inversion of velocity structures using receiver functions, with specific emphasis on the recent advances, challenges, and possible solutions. In the light of the emerging and future trends in seismology, we finally discuss the directions of receiver function studies from the viewpoints of both methodology and application.","source":"DOAJ","year":2022,"language":"","subjects":["Geophysics. Cosmic physics","Astrophysics"],"doi":"10.19975/j.dqyxx.2022-029","url":"https://www.sjdz.org.cn/en/article/doi/10.19975/j.dqyxx.2022-029","is_open_access":true,"published_at":"","score":66},{"id":"doaj_10.1515/jogs-2022-0135","title":"Introducing covariances of observations in the minimum L1-norm, is it needed?","authors":[{"name":"Suraci Stefano S."},{"name":"Oliveira Leonardo C."},{"name":"Klein Ivandro"},{"name":"Goldschmidt Ronaldo R."}],"abstract":"The most common approaches for assigning weights to observations in minimum L1-norm (ML1) is to introduce weights of p or p\\sqrt{p}, p being the weights vector of observations given by the inverse of variances. Hence, they do not take covariances into consideration, being appropriated only to independent observations. To work around this limitation, methods for decorrelation/unit-weight reduction of observations originally developed in the context of least squares (LS) have been applied for ML1, although this adaptation still requires further investigations. In this article, we presented a deeper investigation into the mentioned adaptation and proposed the new ML1 expressions that introduce weights for both independent and correlated observations; and compared their results with the usual approaches that ignore covariances. Experiments were performed in a leveling network geometry by means of Monte Carlo simulations considering three different scenarios: independent observations, observations with “weak” correlations, and observations with “strong” correlations. The main conclusions are: (1) in ML1 adjustment of independent observations, adaptation of LS techniques introduces weights proportional to p\\sqrt{p} (but not p); (2) proposed formulations allowed covariances to influence parameters estimation, which is unfeasible with usual ML1 formulations; (3) introducing weighs of p provided the closest ML1 parameters estimation compared to that of LS in networks free of outliers; (4) weighs of p\\sqrt{p} provided the highest successful rate in outlier identification with ML1. Conclusions (3) and (4) imply that introducing covariances in ML1 may adversely affect its performance in these two practical applications.","source":"DOAJ","year":2022,"language":"","subjects":["Geodesy"],"doi":"10.1515/jogs-2022-0135","url":"https://doi.org/10.1515/jogs-2022-0135","is_open_access":true,"published_at":"","score":66},{"id":"doaj_10.5194/isprs-archives-XLIII-B2-2022-485-2022","title":"SEMANTIC URBAN MESH SEGMENTATION BASED ON AERIAL OBLIQUE IMAGES AND POINT CLOUDS USING DEEP LEARNING","authors":[{"name":"Ł. Wilk"},{"name":"Ł. Wilk"},{"name":"D. Mielczarek"},{"name":"W. Ostrowski"},{"name":"W. Dominik"},{"name":"J. Krawczyk"}],"abstract":"The use of deep machine learning methods for semantic classification of city mesh models is one of the current trends in geoscience development. Thanks to the thriving development of Convolutional Neural Networks (CNNs) it is now achievable to conduct fully automated process of building aforementioned 3D model by means of photogrammetric techniques and supplement it with additional semantic information obtained by Artificial Intelligence (AI) algorithms. In order to guarantee the comprehensiveness of said information it is essential to use an extensive range of 3D data including oblique aerial imagery and aerial laser scanning (ALS). Such comprehensive 3D mesh models may be later implemented in many Digital Twin class solutions additionally supported with modern GIS systems and its algorithms. To proof the validity of this thesis, the article showcases results of research conducted using deep learning based solutions tested on two datasets - real-world data in the form of oblique aerial images and ALS point clouds acquired in Bordeaux, France using novel Leica CityMapper-1 multisensoral system and large-scale dataset from SUM: A Benchmark Dataset of Semantic Urban Meshes. Both subalgorithms make use of CNNs as its core-feature. To perform accurate classification of oblique aerial scenes PSP-Net architecture accelerated by techniques of transfer learning has been used. Second algorithm destined for ALS point clouds utilizes CNN as well, but in this case implementation is based on proprietary architecture. The results of the experiments demonstrate that the utilizing these two mutually complementary solutions to extract new semantic information for city mesh models in proposed manner compared with the state-of-the-art methods achieves competitive classification performance.","source":"DOAJ","year":2022,"language":"","subjects":["Technology","Engineering (General). Civil engineering (General)","Applied optics. Photonics"],"doi":"10.5194/isprs-archives-XLIII-B2-2022-485-2022","url":"https://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XLIII-B2-2022/485/2022/isprs-archives-XLIII-B2-2022-485-2022.pdf","is_open_access":true,"published_at":"","score":66},{"id":"doaj_10.5311/JOSIS.2022.25.204","title":"Modeling walkability by remote sensing as latent walking speed extracted from multiple digital trail maps","authors":[{"name":"Ljiljana Šerić"},{"name":"Marina Tavra"},{"name":"Ivan Racetin"},{"name":"Antonia Ivanda"}],"abstract":"Coordinating and managing teams searching for missing persons in wilderness areas is challenging. Local terrain characteristics and environmental conditions strongly influence how searchers accomplish their search tasks. When making decisions, searchers consult various maps of the area. In this paper we proposed a methodology for mapping characteristics of the area that influence user behavior when walking the area, and define a walkability model of the terrain. We define walkability as a measure of how fast a person can walk through terrain. The observed walking speed depends on factors such as the fitness and motivation of a person walking through the terrain, as well as on assistive features and the configuration of the terrain. In our method, walkability is predicted only as a feature of terrain configuration. We used singular value decomposition (SVD) to transform datasets to extract latent features of the terrain and users from multiple Global Positioning System (GPS) trails. We define the walkability measure as a latent component of walking speed, which is a function of terrain features. Finally, we use a  polynomial regression algorithm to build a model for predicting terrain walkability based on remote sensing imagery from the Sentinel-2 mission. The application of the proposed model is demonstrated in the Kozjak mountain region in the Republic of Croatia.","source":"DOAJ","year":2022,"language":"","subjects":["Geography (General)"],"doi":"10.5311/JOSIS.2022.25.204","url":"https://josis.org/index.php/josis/article/view/204","is_open_access":true,"published_at":"","score":66},{"id":"crossref_10.1016/j.geog.2020.03.003","title":"Template-based smoothing functions for data smoothing in Geodesy","authors":[{"name":"M. Kiani"}],"abstract":"","source":"CrossRef","year":2020,"language":"en","subjects":null,"doi":"10.1016/j.geog.2020.03.003","url":"https://doi.org/10.1016/j.geog.2020.03.003","is_open_access":true,"citations":6,"published_at":"","score":64.18},{"id":"doaj_10.5194/isprs-annals-V-2-2020-95-2020","title":"A HYBRID GLOBAL IMAGE ORIENTATION METHOD FOR SIMULTANEOUSLY ESTIMATING GLOBAL ROTATIONS AND GLOBAL TRANSLATIONS","authors":[{"name":"X. Wang"},{"name":"T. Xiao"},{"name":"Y. Kasten"}],"abstract":"In recent years, the determination of global image orientation, i.e. global SfM, has gained a lot of attentions from researchers, mainly due to its time efficiency. Most of the global methods take relative rotations and translations as input for a two-step strategy comprised of global rotation averaging and global translation averaging. This paper by contrast presents a hybrid approach that aims to solve global rotations and translations simultaneously, but hierarchically. We first extract an optimal minimum cover connected image triplet set (OMCTS) which includes all available images with a minimum number of triplets, all of them with the three related relative orientations being compatible to each other. For non-collinear triplets in the OMCTS, we introduce some basic characterizations of the corresponding essential matrices and solve for the image pose parameters by averaging the constrained essential matrices. For the collinear triplets, on the other hand, the image pose parameters are estimated by relative orientation using the depth of object points from individual local spatial intersection. Finally, all image orientations are estimated in a common coordinate frame by traversing every solved triplet using a similarity transformation. We show results of our method on different benchmarks and demonstrate the performance and capability of the proposed approach by comparing with other global SfM methods.","source":"DOAJ","year":2020,"language":"","subjects":["Technology","Engineering (General). Civil engineering (General)","Applied optics. Photonics"],"doi":"10.5194/isprs-annals-V-2-2020-95-2020","url":"https://www.isprs-ann-photogramm-remote-sens-spatial-inf-sci.net/V-2-2020/95/2020/isprs-annals-V-2-2020-95-2020.pdf","is_open_access":true,"published_at":"","score":64},{"id":"doaj_10.3390/ijgi9040255","title":"Efficient Coarse Registration of Pairwise TLS Point Clouds Using Ortho Projected Feature Images","authors":[{"name":"Hua Liu"},{"name":"Xiaoming Zhang"},{"name":"Yuancheng Xu"},{"name":"Xiaoyong Chen"}],"abstract":"The degree of automation and efficiency are among the most important factors that influence the availability of Terrestrial light detection and ranging (LiDAR) Scanning (TLS) registration algorithms. This paper proposes an Ortho Projected Feature Images (OPFI) based 4 Degrees of Freedom (DOF) coarse registration method, which is fully automated and with high efficiency, for TLS point clouds acquired using leveled or inclination compensated LiDAR scanners. The proposed 4DOF registration algorithm decomposes the parameter estimation into two parts: (1) the parameter estimation of horizontal translation vector and azimuth angle; and (2) the parameter estimation of the vertical translation vector. The parameter estimation of the horizontal translation vector and the azimuth angle is achieved by ortho projecting the TLS point clouds into feature images and registering the ortho projected feature images by Scale Invariant Feature Transform (SIFT) key points and descriptors. The vertical translation vector is estimated using the height difference of source points and target points in the overlapping regions after horizontally aligned. Three real TLS datasets captured by the Riegl VZ-400 and the Trimble SX10 and one simulated dataset were used to validate the proposed method. The proposed method was compared with four state-of-the-art 4DOF registration methods. The experimental results showed that: (1) the accuracy of the proposed coarse registration method ranges from 0.02 m to 0.07 m in horizontal and 0.01 m to 0.02 m in elevation, which is at centimeter-level and sufficient for fine registration; and (2) as many as 120 million points can be registered in less than 50 s, which is much faster than the compared methods.","source":"DOAJ","year":2020,"language":"","subjects":["Geography (General)"],"doi":"10.3390/ijgi9040255","url":"https://www.mdpi.com/2220-9964/9/4/255","is_open_access":true,"published_at":"","score":64},{"id":"doaj_10.1515/jogs-2019-0006","title":"Mass variation observing system by high low inter-satellite links (MOBILE) – a new concept for sustained observation of mass transport from space","authors":[{"name":"Pail R."},{"name":"Bamber J."},{"name":"Biancale R."},{"name":"Bingham R."},{"name":"Braitenberg C."},{"name":"Eicker A."},{"name":"Flechtner F."},{"name":"Gruber T."},{"name":"Güntner A."},{"name":"Heinzel G."},{"name":"Horwath M."},{"name":"Longuevergne L."},{"name":"Müller J."},{"name":"Panet I."},{"name":"Savenije H."},{"name":"Seneviratne S."},{"name":"Sneeuw N."},{"name":"van Dam T."},{"name":"Wouters B."}],"abstract":"As changes in gravity are directly related to mass variability, satellite missions observing the Earth’s time varying gravity field are a unique tool for observing mass transport processes in the Earth system, such as the water cycle, rapid changes in the cryosphere, oceans, and solid Earth processes, on a global scale. The observation of Earth’s gravity field was successfully performed by the GRACE and GOCE satellite missions, and will be continued by the GRACE Follow-On mission. A comprehensive team of European scientists proposed the next-generation gravity field mission MOBILE in response to the European Space Agency (ESA) call for a Core Mission in the frame of Earth Explorer 10 (EE10). MOBILE is based on the innovative observational concept of a high-low tracking formation with micrometer ranging accuracy, complemented by new instrument concepts. Since a high-low tracking mission primarily observes the radial component of gravity-induced orbit perturbations, the error structure is close to isotropic. This geometry significantly reduces artefacts of previous along-track ranging low-low formations (GRACE, GRACE-Follow-On) such as the typical striping patterns. The minimum configuration consists of at least two medium-Earth orbiters (MEOs) at 10000 km altitude or higher, and one low-Earth orbiter (LEO) at 350-400 km. The main instrument is a laser-based distance or distance change measurement system, which is placed at the LEO. The MEOs are equipped either with passive reflectors or transponders. In a numerical closed-loop simulation, it was demonstrated that this minimum configuration is in agreement with the threshold science requirements of 5 mm equivalent water height (EWH) accuracy at 400 km wavelength, and 10 cm EWH at 200 km. MOBILE provides promising potential future perspectives by linking the concept to existing space infrastructure such as Galileo next-generation, as future element of the Copernicus/Sentinel programme, and holds the potential of miniaturization even up to swarm configurations. As such MOBILE can be considered as a precursor and role model for a sustained mass transport observing system from space.","source":"DOAJ","year":2019,"language":"","subjects":["Geodesy"],"doi":"10.1515/jogs-2019-0006","url":"https://doi.org/10.1515/jogs-2019-0006","is_open_access":true,"published_at":"","score":63},{"id":"doaj_10.2478/congeo-2018-0002","title":"Interplanetary external driven quasidynamo as the origin of geomagnetic jerks correlated with length of day and gravity anomaly","authors":[{"name":"Mohsen LUTEPHY"}],"abstract":"We report phenomenological inevitable correlation between the Sun’s magnetic field oscillation through the Earth and the Jupiter, with sinusoidal geomagnetic jerks observed at the Earth, additionally aligned with the gravity and length of day sinusoidal variations and we observe too that the Sun and Jovian planets alignments with Jupiter are origin of the observable abrupt geomagnetic jerks whether historical or new, and experimental results demonstrate a possible explanation on the base of the planetary induced currents upon the metallic liquid cores of the planets upon the varying external magnetic fields as the source of heat flows continued by frictional turbulent and convectional fluid fluxes, amplified and expanding by the Earth magnetic field and observations are showing too that it should be an electric coupling effect between metallic cores of the planets, under the magnetic field oscillation so that Jupiter conductive metallic region interacts with Earth metallic core while the Sun’s magnetic field is oscillating through the Jupiter and we see a relation between secular variation of the Earth’s magnetic field and long term trend of 5.9-years signals as a new method to measure geomagnetic secular variation by LOD signals.","source":"DOAJ","year":2018,"language":"","subjects":["Geodesy","Geophysics. Cosmic physics"],"doi":"10.2478/congeo-2018-0002","url":"https://journal.geo.sav.sk/cgg/article/view/177","is_open_access":true,"published_at":"","score":62},{"id":"doaj_10.3390/rs10071119","title":"Very Deep Convolutional Neural Networks for Complex Land Cover Mapping Using Multispectral Remote Sensing Imagery","authors":[{"name":"Masoud Mahdianpari"},{"name":"Bahram Salehi"},{"name":"Mohammad Rezaee"},{"name":"Fariba Mohammadimanesh"},{"name":"Yun Zhang"}],"abstract":"Despite recent advances of deep Convolutional Neural Networks (CNNs) in various computer vision tasks, their potential for classification of multispectral remote sensing images has not been thoroughly explored. In particular, the applications of deep CNNs using optical remote sensing data have focused on the classification of very high-resolution aerial and satellite data, owing to the similarity of these data to the large datasets in computer vision. Accordingly, this study presents a detailed investigation of state-of-the-art deep learning tools for classification of complex wetland classes using multispectral RapidEye optical imagery. Specifically, we examine the capacity of seven well-known deep convnets, namely DenseNet121, InceptionV3, VGG16, VGG19, Xception, ResNet50, and InceptionResNetV2, for wetland mapping in Canada. In addition, the classification results obtained from deep CNNs are compared with those based on conventional machine learning tools, including Random Forest and Support Vector Machine, to further evaluate the efficiency of the former to classify wetlands. The results illustrate that the full-training of convnets using five spectral bands outperforms the other strategies for all convnets. InceptionResNetV2, ResNet50, and Xception are distinguished as the top three convnets, providing state-of-the-art classification accuracies of 96.17%, 94.81%, and 93.57%, respectively. The classification accuracies obtained using Support Vector Machine (SVM) and Random Forest (RF) are 74.89% and 76.08%, respectively, considerably inferior relative to CNNs. Importantly, InceptionResNetV2 is consistently found to be superior compared to all other convnets, suggesting the integration of Inception and ResNet modules is an efficient architecture for classifying complex remote sensing scenes such as wetlands.","source":"DOAJ","year":2018,"language":"","subjects":["Science"],"doi":"10.3390/rs10071119","url":"http://www.mdpi.com/2072-4292/10/7/1119","pdf_url":"http://www.mdpi.com/2072-4292/10/7/1119","is_open_access":true,"published_at":"","score":62},{"id":"doaj_10.1016/j.geog.2017.09.007","title":"Automated Burris gravity meter for single and continuous observation","authors":[{"name":"Gerhard Jentzsch"},{"name":"Richard Schulz"},{"name":"Adelheid Weise"}],"abstract":"The Burris Gravity Meter™ manufactured by ZLS Corporation, Austin/Texas, USA, is based on the invention of L\u0026R (L. LaCoste and A. Romberg): The ZLS (zero-length spring). A digital feedback system (range of about 50 mGal) is used to null the beam. Now, more than 120 gravity meters of this make exist worldwide and are used successfully in exploration, volcanology, geodetic work and surveying.The sensor is made of the well-known (L\u0026R) metal-alloy zero-length spring providing a low drift characteristic. The drifts observed are comparable to L\u0026R gravimeters and are less than 0.3 mGal per month, which is much lower than the drifts known for the fused quartz sensors.The dial is calibrated every 50 mGal over the entire 7000 mGal meter range. Since the gravity value is determined at these points, there are no periodic errors. By a fourth heater circuit temperature effects are totally avoided. The gravity meter is controlled via Bluetooth® either to a handheld computer (tablet) or a notebook computer.The feedback responds with high stability and accuracy. The nulling of the beam is controlled by the UltraGrav™ control system which incorporates an inherently linear PWM (pulse-width modulated) electrostatic feedback system. In order to improve the handling of the gravimeter we have developed two Windows based programs: AGESfield for single measurements and AGEScont for continuous readings. Keywords: Gravimeter, Micro-gravity measurements, Drift, Resolution, Single and continuous observations","source":"DOAJ","year":2018,"language":"","subjects":["Geodesy","Geophysics. Cosmic physics"],"doi":"10.1016/j.geog.2017.09.007","url":"http://www.sciencedirect.com/science/article/pii/S1674984716301793","is_open_access":true,"published_at":"","score":62},{"id":"doaj_10.15292//geodetski-vestnik.2018.01.13-27","title":"Različni postopki za izračun odklonov navpičnice: primer območja pod Krvavcem ( = Different aspects of the computation of vertical deflection: case study in the area of Krvavec)","authors":[{"name":"Polona Pavlovčič Prešeren"},{"name":"Tanja Petrin"},{"name":"Božo Koler"},{"name":"Tilen Urbančič"},{"name":"Miran Kuhar"}],"abstract":"In coordinate calculation from terrestrial measurements, the reduction due to the Earth's gravity field should be one of the main topics of consideration. The problem is of extreme importance especially in steep areas, where geoid surface is not parallel to the rotational ellipsoid. In this, the knowledge of the deflection of the vertical is significant. There are two ways for its acquisition: from the comparison of astronomic versus geodetic coordinates, or from the indirect way of calculation by using global, regional, or local geoid models. This paper reviews the deflection of the vertical and its use at the steep area under Krvavec. The computation followed from three models, EGM2008 and two Slovene models: the current SLOAGM2000 and the test model SLOAGM2010. In addition, the local geoid model was established from the ellipsoidal and the normal-orthometric heights. Significant differences in vertical deflection components originated from the EGM2008. We can confirm the expectation that in steep areas it is necessary to consider the geoid inclination. The best way to do this is the local geoid surface determination from the ellipsoidal in physical heights. In other cases, local geoid models are still appropriate. Contrary, we should avoid using global models because of their lower resolution.","source":"DOAJ","year":2018,"language":"","subjects":["Geodesy"],"doi":"10.15292//geodetski-vestnik.2018.01.13-27","url":"http://geodetski-vestnik.com/62/1/gv62-1_preseren.pdf","is_open_access":true,"published_at":"","score":62}],"total":34596,"page":1,"page_size":20,"sources":["DOAJ","CrossRef"],"query":"Geodesy"}