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Journal

Journal of Applied Geodesy

Editors-in-Chief: Hans-Berndt Neuner and Chris Rizos

Language: English

First published: March 22, 2007

Publication Frequency: 4 issues per year

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About this journal

Objective
The Journal of Applied Geodesy (JAG) is a forum for peer-reviewed research articles in the area of application of geodesy to engineering and other natural sciences. It publishes innovative contributions on sensor developments, multi-sensor systems and sensor data fusion focusing on the capture of georeferenced data. Hence topics related to navigation and mobile mapping will also be covered by JAG. The scope includes optical and microwave 3-D measurement techniques and other sensors for geotechnical measurements. Furthermore, applied geodesy articles from all areas of satellite-based geodetic networks, deformation measurements, deformation analysis, modelling of local geodynamic processes and the development of intelligent alert systems, measurement techniques for large construction sites and mechanical engineering will be presented. With increased use of the tools of Artificial Intelligence for sensor control, sensor fusion and data analysis, manuscripts on these topics with a strong emphasis on applied geodesy will also be published.

Topics

Navigation and mobile mapping
Optical and microwave 3-D measurement techniques
Satellite-based geodetic networks
Deformation measurements
Deformation analysis
Modelling of local geodynamic processes
Intelligent alert systems
Measurement techniques for large construction sites
Mechanical engineering
Sensor control
Sensor fusion

Article formats
Research articles

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Your Benefits

Your benefits:

Novel fields of application of geodesy to engineering and other natural sciences
Rapid developments that have influenced both sensors / instrumentation and methodology
Cutting-edge surveying and mapping techniques, processing algorithms and analytical tools
Rigorous peer-review

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Mitigation of chirp interference in NavIC signals using NWPR and SNV estimator

September 23, 2025

Divyasree Uddandapu, Surya Narayana Murthy Tummala

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Radio Frequency Interference (RFI) makes it very difficult for Global Navigation Satellite Systems (GNSS) signals to work properly and remains safe. This makes positioning less accurate and reliable. This study looks at the current methods for finding and reducing RFI, with a focus on the IRNSS S-band and L5-band, because it covers the whole world. In this, how the chirp interference affects signal tracking by measuring the Carrier-to-Noise Ratio ( C / N 0 ) using in-phase and quadrature-phase correlator outputs under both statistical and estimated settings. The narrowband-wideband power ratio (NWPR) approach boosts effective C / N 0 by 11.37 dB-Hz for the S-band signal and 12.48 dB-Hz for the L5-band signal, and compares it to the statistical C / N 0 value and the Signal to Noise variance estimator C / N 0 .
Open Access
Exploring LSTM neural networks for sea level forecasting based on two-decadal tidal and meteorological data

September 22, 2025

Nestoras Papadopoulos, Vassilis Gikas

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The analysis of long-term sea level signal fluctuations and their systematic forecasting showcase the value and implications not only for oceanographic, climate monitoring and related studies but also, on socio-economic aspects of life. Such changes affect significantly the stability in natural processes functioning as well as the usage of nearshore infrastructures; and therefore, interrelate to human activities in coastal areas. This study contributes to the forecasting of sea level variation employing emerging Deep Learning techniques in the form of Recurrent Neural Networks, particularly Long Short-Term Memory (LSTM). Several combinations of data were tested exhaustively to identify the most suitable setup and examine the accuracy depending on available datasets. Univariate, multivariate and multivariate to univariate LSTMs were formed and hyperparameter tuning took place exhibiting RMSE values around 4–5 cm. Also, the effect of seasonality and trend to LSTM forecast was investigated thoroughly leading to performance improvement after eliminating it from the network. The combination of the above networks introduced the “fill-in and predict” technique leading to RMSE slightly over 1 cm for the multivariate to univariate LSTM network. The forecast results were validated against more than two years of historical data.
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Investigations on different spectral techniques to improve the gravimetric geoid model for the central part of Java, Indonesia, using terrestrial, airborne, and altimetric-based gravity observations

September 18, 2025

Brian Bramanto, Rahayu Lestari, Arisauna M. Pahlevi, Kosasih Prijatna, Agustina N. Syafarianty, Dina A. Sarsito, Vera Sadarviana, Widy Putra, Bagas Triarahmadhana, Teguh P. Sidiq, Safirotul Huda, Febriananda Ladivanov, Muhammad S. Fathulhuda, Irwan Gumilar, Dudy D. Wijaya

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In the modern era, deriving accurate geoid models is crucial for various engineering and geoscience applications. The geoid facilitates the transformation of ellipsoidal heights from Global Navigation Satellite System (GNSS) measurements to orthometric heights and aids in determining geostrophic ocean surface currents. This study assesses different spectral methods, including two-dimensional Fast Fourier Transform (FFT), multiband spherical FFT, and one-dimensional FFT, for evaluating the Stokes’ function in gedsaata and Stokes’ kernel. The geoid modeling process is divided into three major stages: gravity data assessment, regularization of scattered gravity datasets onto the topographical surface, and geoid computation under the Remove-Compute-Restore (RCR) mode with Residual Terrain Model (RTM) reduction. Results indicate that the multiband spherical FFT method outperforms others, leading to the adoption of the Institut Teknologi Bandung-Central Java 2024 (ITBCJ24) geoid model, which achieves a root mean squared error (RMSE) of 0.068 m relative to GNSS-leveling observations and a relative accuracy of 4.409 ppm. The study also highlights the significance of gravity data coverage and distribution by comparing geoid models derived from terrestrial, airborne, and altimetric-derived gravity observations against the model relying solely on terrestrial gravity observations. Although the latter performs similarly at validation points, prominent discrepancies in geoidal height outside the validation region highlight the importance of uniform and dense gravity data coverage. Finally, the ITBCJ24 geoid model is compared to existing geoid models in Indonesia, showcasing its superiority with RMSE values of 0.117 m and 0.166 m for Indonesia’s regional geoid model of INAGEOID2020 and Earth Geopotential Model 2008 (EGM2008) model, respectively.
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Comparative analysis of CYGNSS-derived soil moisture and its spatiotemporal distribution across Egypt and Africa

September 18, 2025

Ahmed Salah El-Din, Ibrahim Fouad Ahmed, Ashraf El-Kutb Mousa, Gamal El-Fiky

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Soil Moisture Content (SMC) is a crucial variable influencing Earth’s environmental processes, including the water cycle, energy balance, and carbon cycle. Global Navigation Satellite System Reflectometry (GNSS-R) has emerged as a powerful tool for monitoring SMC. The Cyclone Global Navigation Satellite System (CYGNSS), a mission consisting of eight microsatellites launched by NASA in 2016, utilizes GNSS-R to provide high-temporal-resolution soil moisture estimates. This study conducts a comparative analysis of CYGNSS-derived SMC data against SMAP, SMOS, CEDA, and ERA5 datasets over Egypt and Africa from 2017 to 2021. Using tolerance and interpolation techniques, the analysis revealed strong correlations between CYGNSS and the other datasets, with overall correlation values of 0.78 (SMAP), 0.64 (SMOS), 0.74 (CEDA), and 0.80 (ERA5). The corresponding RMSE values were 0.022, 0.018, 0.027, and 0.035 cm 3 /cm 3 , respectively. Interpolation results showed correlations of 0.76, 0.47, 0.54, and 0.39, with RMSE values of 0.03, 0.065, 0.045, and 0.076 cm 3 /cm 3 , respectively. Additionally, the study analyzes the spatiotemporal distribution of soil moisture across Egypt and Africa, revealing regional variations and trends over the study period. These findings demonstrate CYGNSS’s effectiveness in capturing soil moisture variations, particularly in Egypt.
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Investigation the impact of active fault-induced vertical displacement on land subsidence rates using GNSS CORS data in northern coastal cities of Central Java, Indonesia

August 27, 2025

Muhammad Arif Mumtaz, Cecep Pratama, Leni Sophia Heliani, Dwi Lestari, Krishna Duta Wibisono, Zulviana Rahmadina, Nur Intan Komala Dewi, Nicholas Genta Setiawan Gunawan, Sidik Tri Wibowo

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Land subsidence is commonly observed along the coastal regions of Java Island, particularly in the northern part of Central Java. This phenomenon often contributes to the intensification of coastal flooding. Subsidence rates are influenced by multiple factors, which might also relate to tectonic movements associated with active fault structures. In this study, we investigate the contribution of active fault-induced deformation to land subsidence in northern coastal cities of Central Java. We modeled the surface displacements resulting from active faults using the elastic half-space approach. We analyzed geodetic data from Continuously Operating Reference Stations (CORS) situated along the northern coast, covering the period from 2015 to 2019. The analysis revealed notable land subsidence at Pekalongan and Tegal, with annual rates of −122.54 mm/year and −11.04 mm/year, respectively. Statistical testing of annual displacement rates indicated that fault-induced surface movement was significant only at Semarang City. Conversely, the displacement observed at CORS with pronounced subsidence was not statistically significant. These findings suggest that active fault-related displacements do not play a dominant role in driving land subsidence in the study area. Instead, the magnitude of their influence appears to depend on the proximity of the faults to observation sites and the relative level of earthquake potential of the fault.
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Investigating the relationship between accuracy and orders of global geopotential models over GNSS/Levelling stations: a case study of Egypt

August 7, 2025

Gomaa M. Dawod, Essam M. Al-Krargy, Ghada G. Haggag

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Although there are several factors could affect the accuracy performance of Global Geopotential Models (GGMs), the current research investigates if the order of a model represents the key aspect influencing its accuracy. Fourteen GGMs, with variable orders, have been selected to be tested over 1,100 Global Navigation Satellite Systems (GNSS)/Levelling stations in Egypt. The performance of global models has been analyzed against that of a national geoid model. Additionally, the performance of GGMs over variable topography in Egypt has been investigated too. Based on the available data and the attained findings, it has been found that the low-order GGMs produced mean geoid undulations very far from that of the national model. Over the available checkpoints, it has been recognized that the accuracy of high-order GGMs is less than ± 0.276 m. However, a particular medium-order model produced a better performance with a standard deviation equals ± 0.193 m. Other medium-order models resulted in accuracy varies between ± 0.238 m and ± 0.371 m. In addition, the models produced slightly better performance over high-elevation topography in Egypt. Furthermore, statistical analysis demonstrates that the correlation between model’s order and accuracy equals −0.38 which indicates that such an association is weak. The regression coefficient of determination has been estimated as 0.14 which concludes that the regression is feeble since only 14 % of the accuracy variations are affected by the model’s order. Such remarks highlight that there is no significant association between the order and accuracy of GGMs over GNSS/Levelling stations in Egypt.
Open Access
Sensitivity quantification of spatially averaged displacement estimates in TLS-based geomonitoring

July 31, 2025

Lorenz Schmid, Tomislav Medic, Nicholas Meyer, Andreas Wieser

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Terrestrial Laser Scanning (TLS) is increasingly used in geomonitoring for 3D displacement analysis. However, assessing the sensitivity of the implemented monitoring strategy, which is crucial for correctly interpreting observations and detecting deformations, is challenging due to the impact of complex spatial correlations and other influencing factors. Traditional methods for sensitivity analysis often assume uncorrelated measurements, leading to biased and overestimated sensitivity. This can lead to suboptimal choices of monitoring strategy, false expectations, and errors in displacement detection. This study introduces a new method for quantifying the uncertainty of spatially aggregated (averaged) TLS-based displacement estimates in geomonitoring by empirically locally sampling such aggregated values (ELSA). The method implicitly accounts for the mentioned spatial correlations and their local variations, therefore, providing a more realistic sensitivity quantification. Validation using real-world datasets and simulated displacements demonstrates the method’s ability to provide a realistic uncertainty estimate and, subsequently, a good sensitivity estimate, realized herein by means of the Minimal Detectable Bias (MDB). Finally, we investigated several data preprocessing steps and demonstrated their effectiveness in enhancing both sensitivity and the quality of uncertainty estimates.
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Quality analysis of reference GPS stations in Ecuador

June 30, 2025

Richard Serrano-Agila, Rosendo Romero-Andrade, Daniel Hernández-Andrade, Wilman Gonzalo Merino-Vivianco

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Since 2008, Ecuador has established a Permanent Geodetic Network (REGME), to support geodetic research in the country. The REGME network plays a critical role in monitoring tectonic activity and crustal deformation throughout Ecuador. However, no comprehensive quality analysis has been conducted for REGME stations. The network has provided data from 70 continuous GPS stations across Ecuador, covering a period of 16 years. Shell scripts were developed on UNIX to manage and process REGME raw data. The data were converted from HATANAKA to RINEX format using CRX2RNX, and the sampling rate was standardized to 30 s using TEQC software. Only GPS signals were selected due to variations in the stations’ capabilities to track different signals. This study establishes a crucial foundation for future research on crustal deformation and geophysical phenomena in the region, offering valuable insights that will enhance both local and global geodetic efforts.
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Investigating the preparation phase of volcanic eruptions using Swarm and GPS-TEC satellite data: The case of the 29 May 2024 Iceland-Sundhnúkur volcanic eruption

June 27, 2025

Mehdi Akhoondzadeh

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In the last 6 months, 5 eruptions have been reported at the location of Iceland’s volcanoes. In this study using the electron density and temperature data measured by the LP sensor onboard the Swarm satellites (A, B, C), the volcanic ionospheric anomalies around the location and time of the Sundhnúkur volcano have been investigated. Most parameters measured by the three Swarm satellites show striking anomalies on 34 and 8 days before the eruption. Also, in this study, GPS-TEC data were used as a volcanic precursor, and median-interquartile method was implemented to detect hidden and highly nonlinear volcano-ionospheric anomalies. This precursor detected clear anomalies in the time interval of 8 days before the eruption. Also, the values of AOD (Aerosol Optical Depth) parameter indicate abnormal behavior on 9 days prior to the event. To reduce the uncertainty of the detected volcanic anomalies, a confutation analysis was also performed, and no clear anomalies were observed in the same spatial and temporal interval studied, but in 2019. The observed anomalies are consistent with geological and seismic reports. For more detailed analysis, we separately investigated the tracks of the satellites crossing the volcano’s buffer zone. Observed anomalies in the time series analysis were acknowledged. Therefore, the results of this study emphasizes that Swarm satellite data, along with other satellite and field data, can be used to predict, detect and track volcanic activities and it is shown that by comparison with other lithospheric and atmospheric precursors, uncertainty in eruption prediction can be reduced.
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Assessing ground deformation monitoring techniques in Midvaal, South Africa

June 27, 2025

Thobani Maluleka, Siphiwe Matthews Mphuthi

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Ground subsidence, the gradual sinking of the earth’s surface, poses a significant challenge globally, affecting regions like Midvaal, South Africa. This study employed Persistent Scatterer (PS) and Small Baseline Subset (SBAS) InSAR time-series analysis, continuous Global Navigation Satellite Systems (cGNSS) validation, and Random Forest machine learning to monitor and model ground subsidence using Sentinel-1 data (2019–2021). SBAS InSAR showed higher ground subsidence rates than PS InSAR, with cGNSS validation revealing InSAR limitations. Factor analysis identified NDVI, NDWI, lithology, and elevation as key drivers. The Random Forest model generated a susceptibility map, classifying areas into five vulnerability levels. Results indicate that Midvaal experiences significant ground subsidence, likely due to groundwater extraction for agricultural activities and mining, impacting approximately 3.4 % of the study area (118.85 sq. km). This study provides critical insights for sustainable land management and infrastructure planning in ground subsidence-prone regions.
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Developing Malaysia continuous hydrographic datum (MyCHD) by assimilating tide gauge, satellite altimeter, and global hydrodynamic model

June 27, 2025

Mohd Faizuddin Abd Rahman, Mohammad Hanif Hamden, Ami Hassan Md Din, Mohd Razali Mahmud

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The advancement of multi-mission satellite altimeters has greatly enhanced the conventional approach of using a tide gauge station to establish a localised hydrographic datum. However, there are still several limitations in continually depending on a small number of sparsely distributed tide gauge stations and wide satellite altimeter track missions, even with its continuous monitoring of ocean data at local and worldwide coverage. Such limitation has left a region farther away from the satellite altimeter track and tide gauge stations without any hydrographic data. Hence, this study aims to develop Malaysia’s Continuous Hydrographic Datum (MyCHD) by combining the satellite altimeter, tide gauge station, and global hydrodynamic model (GHM). In addition, the reliability of MyCHD was also assessed to determine the rate of improvement by incorporating GHM as additional hydrographic data. The research methodology involves collecting data from the Department of Survey and Mapping Malaysia (DSMM) tide gauge stations along Malaysia’s coastline, as well as satellite altimetry data from TOPEX, Jason-1, Jason-2, and GEOSAT Follow-On (GFO) via the Radar Altimeter Database System (RADS). Additionally, Indian Ocean GHM data from Oregon State University (OSU) was also utilised. The tide gauge, satellite altimetry, and GHM datasets encompass 26 years of tidal observations, spanning from 1993 to 2018. All hydrographic data were processed using harmonic analysis in Unified Tidal Analysis and Prediction (UTide) within MATLAB to establish the hydrographic datum. The derived Lowest and Highest Astronomical Tide (LAT and HAT) from tide gauge, satellite altimetry, and GHM data were referred to the Mean Sea Level (MSL) for compatibility in data integration; these were designated as LAT MSL  and HAT MSL , respectively. Then, using ArcGIS software, the LAT MSL  and HAT MSL were interpolated using Inverse Distance Weighting (IDW). In contrast to the integration of tide gauge and satellite altimeter, the statistical assessment showed that the integration of tide gauge, satellite altimeter, and GHM has a better agreement with the DSMM tide gauges, with a Root Mean Square Error (RMSE) of ± 0.671 m for LAT MSL and ± 0.370 m for HAT MSL . In percentage terms, incorporating GHM data with tide gauge and satellite altimeter in establishing MyCHD has significantly improved its reliability by 17 % for LAT MSL and 30 % for HAT MSL respectively. In conclusion, the hydrographic datum is now available at any coordinate along Malaysia’s coast with the establishment of MyCHD (LAT MSL and HAT MSL ).
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GNSS interferometric reflectometry as a passive remote sensing method for studying environmental phenomena

June 26, 2025

Mohamed Abdelhamid

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Global Navigation Satellite System Interferometric Reflectometry (GNSS-IR) is a versatile remote sensing technique that utilizes reflected GNSS signals for environmental monitoring. By analyzing interference patterns between direct and reflected GNSS signals, GNSS-IR enables the estimation of surface characteristics such as soil moisture, water level, and snow depth. This study investigates snow accumulation, soil moisture, and water level measurements using GNSS-IR over extended periods, providing insights into climate-related trends. Data from GNSS stations in both the northern and southern hemispheres were analyzed. Snow depth was monitored at two stations over a decade, revealing fluctuations in accumulation and highlighting potential impacts of climate change. Soil moisture was analyzed at a grass-covered site, with comparisons before and after vegetation correction. Water levels were measured using GNSS-IR data near a coastal stream, capturing clear tidal signatures. Results show consistent reflector height variations corresponding to snow depth changes, soil moisture dynamics, and water level oscillations (including tides), demonstrating the robustness of GNSS-IR for environmental monitoring of snow, soil moisture, and sea level.
Open Access
Linking persistent scatterers to airborne laser scanning points for identifying real objects reflecting SAR signal

June 25, 2025

Natalia Wielgocka, Grzegorz Jóźków, Freek van Leijen, Ramon Hanssen, Kamila Pawłuszek-Filipiak

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The Persistent Scatterers Interferometry (PSI) method enables displacement estimation with millimeter accuracy. However, the uncertain positioning of Point Scatterers (PS) makes it difficult to associate them with real objects in space and hampers the interpretation of the results. This article proposes a methodology to enhance the accuracy of PS positions. The methodology successfully establishes links between PS and real objects by associating them with the most likely candidate points extracted from Airborne Laser Scanning (ALS) point clouds. The selection process for suitable candidates is based on ALS analysis of return number, classification, and geometric features determined by neighborhood analysis. The linking process involves determining global transformation parameters for PSs using the Iterative Closest Point (ICP) algorithm. Then, the nearest neighbor search within the error ellipsoid of the PS positions is performed. Tests conducted demonstrated that this method allows for linking more than 80 % and 65 % of the PS derived from Sentinel-1 and TerraSAR-X mission data, respectively, in both ascending and descending geometries. To validate the obtained results, in addition to the quantitative assessment, a qualitative analysis is performed based on a developed 3D visualization module showing all stages of the proposed methodology.
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Statistical analysis of Precipitable Water Vapor and rainfall variability in different geographical conditions of the Indian region

June 25, 2025

Aaryan Kulkarni, Vesapogu Sujana Deepthi, Nishant Kumar, Sridhar Miriyala, Devanaboyina Venkata Ratnam

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Monitoring Precipitable Water Vapor (PWV) with Global Navigation Satellite System (GNSS) receivers is becoming a more viable and effective solution for meteorological applications such as rainfall prediction, climate change, and weather forecasting etc. This study investigates the statistical relationship between GNSS-derived Precipitable Water Vapor (PWV) and rainfall variability across five Indian cities, Bangalore, Hyderabad, Guwahati, Thiruvananthapuram, and Madurai, representing diverse geographic and climatic zones. GNSS-derived PWV data from the GPS Aided Geo Augmented Navigation (GAGAN) network and rainfall data from the Indian Meteorological Department (IMD) were considered from March 2013 to February 2014. Data has been analyzed based on seasonal trends and the dynamic interaction between atmospheric moisture and precipitation. The results represented significant spatial and temporal differences in rainfall patterns, with Thiruvananthapuram recording the highest monthly rainfall (143.90 mm in October 2013) due to dual monsoon exposure, and Madurai the lowest (88.5 mm in October 2013) owing to its rain-shadow location. Guwahati shows strong orographic influence and early monsoon peaks (121.30 mm in June 2013), while inland cities like Bangalore and Hyderabad experience delayed rainfall peaks during post-monsoon periods. Average monthly rainfall and PWV values were found to be closely linked to geographical factors such as elevation, topography, and proximity to coastlines. A clear correlation was observed between PWV and subsequent rainfall events; sharp increases in PWV exceeding 30 mm daily or rising at rates above 0.5 mm/h often preceded heavy precipitation.
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Evaluating stochastic models for estimating site velocity from daily and weekly GNSS time series in the stable region of the South American plate

June 23, 2025

Haroldo Antonio Marques, Lucas Gonzales Lima Pereira Calado, João Francisco Galera Monico, Heloisa Alves Silva Marques, Maurício Carvalho Mathias de Paulo, Gabriela de Oliveira Nascimento Brassarote

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Accurate estimation of GNSS station velocities requires a precise characterization of stochastic noise in coordinate time series. This study evaluates stochastic models for estimating site velocities using weekly network and daily PPP GNSS solutions from 74 stations in the stable South American mid-plate. The functional model incorporated seasonal components, while the stochastic model was based on noise variance estimates. The Non-Negative Least Squares Variance Component Estimation method was applied to estimate noise amplitudes, classifying noise as a combination of white and colored components. Additionally, the spectral index was refined using Maximum Likelihood Estimation. Results show that most time series are best described by a combination of white and flicker noise, with differences in spectral properties between weekly and daily solutions. The impact of these models on velocity uncertainties was assessed, showing that neglecting an appropriate noise model can lead to overestimated uncertainties. These findings contribute to improving GNSS-based velocity estimations for geodynamic studies.
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Regional assessment of high-degree combined global gravity field model for geoid modelling over Nigeria

June 23, 2025

Michael Bako

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Given the multitude of global gravity field model (GGMs) at our disposal, evaluating them against independent data is indispensable for delineating their quality and ascertaining their accuracy in Nigeria regions. In this study, we evaluated five combined GGMs (specifically SGG-UGM-2, XGM2019e_2159, GECO, EIGEN-6C4, and EGM2008) over Nigeria. Our evaluation is conducted using geoid undulations (mainly in FCT-Abuja) and free-air gravity anomalies (covering the whole country, Nigeria). The results showed that the differences between observed and GGMs implied geoid undulations at 20 GNSS/levelling points over FCT-Abuja (small area) revealed that XGM2019e_2159 fit better with standard deviation (SD) of 11.9 cm over the study area compared to other four evaluated combined GGMs. On the other hand, SD of the differences between observed and GGMs implied free-air gravity anomalies over Nigeria showed that XGM2019e_2159 performs slightly better than the other four evaluated combined GGMs with an SD of 7.04 mGal. These results further indicate a good prospect for the development of a precise gravimetric geoid model over Nigeria using XGM2019e_2159 model. However, more GNSS/levelling stations will be required for fittings of the gravimetric geoid model to the national vertical datum of Nigeria.
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Global equatorial F- and E-region ionospheric irregularities from COSMIC-RO and SCINDA-GNSS observations

June 13, 2025

Aramesh Seif, Sampad Kumar Panda, Scott M. Bailey

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This study utilizes data from the FORMOSAT-3/Constellation Observing System for Meteorology, Ionosphere, and Climate radio occultation (COSMIC-RO) observations and ground-based Scintillation Network Decision Aid (SCINDA) GNSS recordings at four longitudinal stations situated in the vicinity of the magnetic equator for probing the characteristics of the ionospheric F and E region irregularities in the equatorial region. We utilize the amplitude scintillation index (S4) derived from these datasets to understand the morphology of nighttime and daytime plasma irregularities in the equatorial ionosphere. By combining ground-based data with a limb-viewing geometry from space, valuable complementary information has been obtained on the nighttime/daytime scintillation occurrences and their morphological associations with the equatorial irregularities in the F (equatorial plasma bubbles, EPB) and E (sporadic E layer; Es) region ionosphere. The occurrence of amplitude scintillation retrieved from COSMIC RO data was calculated to analyze its diurnal and seasonal variations. By conducting a statistical analysis on a dataset in 2013, we observed that the occurrence of ionospheric scintillation, as measured by both techniques, displayed similar variations. In this study, it is observed that scintillation in daytime is associated with Es and is predominantly seen over the Asian sector whilst nighttime scintillation associated with plasma bubbles is most frequently observed in the African sector. These results emphasize the need for RO profiles from active missions to serve as effective tools for monitoring scintillation events both regionally and globally.
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Intrinsic and extrinsic calibration of a UAV-based multi-sensor system

May 23, 2025

Arman Khami, Ingo Neumann, Sören Vogel

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The integration of multiple sensors, such as cameras and LiDARs, is increasingly employed in vehicle navigation and 3D environmental mapping. Accurate multi-sensor data fusion relies heavily on the precise estimation of extrinsic parameters, which define the geometric transformations between sensors. However, when low-cost sensors are used, systematic errors in their intrinsic characteristics often introduce inaccuracies in subsequent applications. To address this challenge, we investigate the impact of intrinsic calibration of a low-cost LiDAR on the accuracy of its extrinsic calibration parameters. Our study evaluates a generalized intrinsic calibration approach that assumes a single scale factor and bias for the LiDAR’s laser rays, in contrast to a detailed model where individual scale factors and biases are estimated for each ray. While the generalized approach exhibits noticeable deviations from the systematic parameters of some rays, it has a substantial positive impact on the estimated extrinsic parameters of the LiDAR, leading to improved mounting accuracy. This improvement highlights the critical role of intrinsic calibration in achieving reliable extrinsic calibration for multi-sensor systems. To ensure robust extrinsic calibration, we decouple the intrinsic and extrinsic calibration processes, thereby providing rectified input data for extrinsic calibration. Furthermore, we present an extrinsic calibration approach for a multi-sensor system comprising an inertial measurement unit, two cameras, and a LiDAR, where the cameras and LiDAR share only a narrow overlapping field of view, resulting in minimal shared information. By employing a high-accuracy reference instrument, we address the limited overlap issue and validate both the extrinsic calibration results and the impact of the LiDAR’s intrinsic calibration. Our findings demonstrate that untreated LiDAR intrinsic errors lead to significant deviations in the extrinsic calibration parameters, underscoring that intrinsic calibration is not merely a preliminary step but a vital factor in ensuring accurate extrinsic calibration in multi-sensor systems.
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Assessment of temporal variations of geoid, ellipsoidal and orthometric heights at proposed IHRF sites using space geodetic data

May 23, 2025

Walyeldeen Godah, Samuel Milki Yadeta, Malgorzata Szelachowska, Georgia Fotopoulos

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The determination of accurate geoid, ellipsoidal and orthometric heights is essential for applications related to surveying engineering, geodetic and geoscience research. The International Association of Geodesy (IAG) defined the International Height Reference System (IHRS) as the conventional gravity field-related global height system. The realization of the IHRS to establish an International Height Reference Frame (IHRF) and its temporal variations, is an ongoing geodetic task. The objective of this research is to assess temporal variations of geoid, ellipsoidal and orthometric heights at proposed IHRF sites using space geodetic data, namely Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GRACE-FO), Global Navigation Satellite Systems (GNSS), Very Long Baseline Interferometry (VLBI), Satellite Laser Ranging (SLR), Doppler Orbitography and Radio-positioning Integrated by Satellite (DORIS) and hydrological model. GRACE/GRACE-FO-based and GLDAS-based Global Geopotential Models were utilized to determine temporal variations of geoid height (Δ N ) and time-dependent changes of ellipsoidal height (Δ h ) at proposed IHRF sites. Moreover, Δ h at proposed IHRF sites were also obtained from GNSS, VLBI, SLR and DORIS solutions. Temporal variations of orthometric height (Δ H ) at proposed IHRF sites were determined by combining Δ N and Δ h . Results reveal that Δ N , Δ h , and Δ H at proposed IHRF sites are not negligible as they can reach several centimetres in terms of seasonal variations and at the and 1 cm level annually. These Δ N , Δ h , and Δ H would be required for the modernization and unification of international/national vertical datums in addition to contemporary requirements for precise height measurements.
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An autoregressive adaptive Kalman filter carrier tracking approach for mitigating ionospheric scintillation effects in GNSS receivers

April 29, 2025

Ram Kumar Vankadara, Melania Susi, Abhijit Dey, Emanuele Pica, Alex Minetto, Sampad Kumar Panda

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Ionospheric scintillation causes a serious threat to the accuracy, integrity, and reliability of Global Navigation Satellite System (GNSS) receivers, leading to significant amplitude fading, and rapid phase fluctuations. The GNSS receivers with traditional carrier-tracking loops may sometimes fail to retain signal integrity during high scintillation scenarios, leading to degraded positioning performance or even loss of lock and can seriously affect the dynamic systems and safety of life-critical applications. We present an Autoregressive Adaptive Kalman Filter (AR-KF) based tracking approach to enhance the robustness of the GNSS receivers under scintillation conditions. The adaptive KF algorithm in the proposed framework dynamically adjusts the time-varying characteristics of the parameters in its tracking loop by leveraging insights gained from a sophisticated and high rate software defined radio-frequency (RF) system collocated by a specialized ionospheric monitoring GNSS receiver whereas the succeeding AR algorithm plays a crucial role by intelligently predicting and refining the carrier phase estimates, thereby mitigating the distortions and enhancing the GNSS tracking loop resiliences. The efficacy of the proposed filtering algorithm is evaluated using real-time GNSS signals affected by weak, moderate, and strong scintillation conditions. Experimental results demonstrate that the combined approach in this work can ensure relatively robust navigation and timing performance by effectively tracking even in severe scintillation conditions. The analysis revealed minimal intervention of the algorithm during weak scintillation but intelligently improving the performance in moderate, and strong scintillation scenarios. The findings from this study suggest the effectiveness of integrating adaptive KF and AR architecture through advanced signal processing methodologies into GNSS receivers, offering a consistent solution for navigational applications during strong scintillation conditions.
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Assessment of orthometric height determination utilizing network of multi-baselines of GNSS Continuously Operating Reference Stations

April 29, 2025

Chaiyaporn Kitpracha, Panithan Bamrungrad, Chalermchon Satirapod

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Global Navigation Satellite Systems (GNSS) offer a modern, efficient alternative to traditional leveling methods, with advantages in accuracy, cost-effectiveness, and adaptability to diverse terrains. This study examines GNSS leveling techniques using Thailand’s Continuously Operating Reference Station (CORS) network. A multi-baseline network approach is proposed to enhance redundancy, enabling weighted least squares adjustment for both absolute and relative methods. The performance of the multi-baseline approach is compared to the single-baseline method to assess its benefits. Results indicate that the multi-baseline absolute method achieves an accuracy of approximately 4 cm, surpassing the single-baseline absolute method and demonstrating a robustness to orthometric height errors caused by reference station anomalies. On the other hand, the relative method shows degraded performance for both single and multi-baseline approaches due to biases in antenna eccentricity, which necessitate reducing the ellipsoidal height at the marker point to the Permanent Bench Mark (PBM) level.
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Post-midnight impact of ionospheric irregularities on GPS based kinematic precise point positioning

April 24, 2025

Mohammed Yousuf, Sridhar Miriyala, Nirvikar Dashora

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The kinematic precise point positioning (KPPP) is one of the best techniques aiming for zero-difference precise positioning. Recent studies have shown a growing use of KPPP in several kinematic platform-based applications for precision approach. This study therefore aims to explore the impact of the ionospheric plasma density perturbations on the KPPP, which bear significant effect over the global equatorial and low latitude belt. With a unique data set of simultaneous observations from a reference station and a close-by scintillation monitoring station located within Hyderabad in India, a study of impact of post-midnight scintillations on KPPP is performed. A 4-year duration around peak of the solar cycle 24 between 2013 and 2016 is considered for KPPP analysis by GipsyX software using continuous observations. The daily ENU (east, north, up) residuals are obtained by subtracting the monthly mean precise position from the daily 30-s sampled KPPP estimates. Then the nighttime ENU residuals (between 18:00 and 06:00 Indian standard time, IST) are segregated into pre-midnight (18:00 to 00:00 IST) and post-midnight (00:00 to 06:00 IST) intervals for all the nights. Owing to a different nature of post-midnight irregularities over the equatorial and low latitudes, the results are obtained for post-midnight KPPP. The amplitude scintillation index S4 is obtained for the corresponding nights for all the days and simultaneous records are used to obtain a few case studies of very high ENU residuals reaching up to 20 m in some cases. Also, the statistical analysis of the ENU shows a decreasing trend in the amplitude of ENU perturbations from midnight to morning hours, wherein, maximum perturbations are observed from 00:00 to 01:00 local time. Conclusions are presented in comparison with the previous literature, and it is found that this could possibly be the first report of the post-midnight impact of the ionospheric scintillation on the KPPP over Indian region.
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Estimation of GPS-based ionospheric indices by GIX, SIDX, and ROTI during the St. Patrick’s Day geomagnetic storm event in the Indian low latitude region

April 24, 2025

Srilatha Talluri, Ravi Kumar Mokkapati, Swapna Raghunath, Venkata Ratnam Devanaboyina

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The disturbance in ionospheric conditions caused by geomagnetic storms leads to problems with the ground, satellite communication, and navigation technology. The Ionospheric perturbations affect the accomplishment of the Global Navigation Satellite System (GNSS), namely accuracy, continuity, availability, and integrity. During the ionosphere’s disturbance level, the Precision and safety of GNSS applications are essential to obtain data about space weather conditions. Along different GNSS satellite receiver paths, GNSS receivers are particularly vulnerable to expeditious changes in Total Electron Content (TEC) and critical spatial variations. The ionospheric indices, namely the Gradient Ionosphere Index (GIX), Rate of TEC Index (ROTI), and the Sudden Ionospheric Disturbance Index (SIDX), are employed for monitoring ionospheric conditions. The ionospheric disturbances can be assessed using GIX and SIDX without prior data. These indices have been modeled and validated based on GNSS observations provided by the Indian region. This research work examines the effects of the ionosphere on the St. Patrick’s Day geomagnetic storm (17th March 2015) by inspecting TEC variations from March 14 to 19, 2015, using spatial and temporal indices for GNSS stations at Trivandrum, Hyderabad, Mumbai, Kolkata, Bhopal, Delhi positioned in the Indian subcontinent. In low-latitude regions, the highest GIX, ROTI, and more negative SIDX values started recording from 1,200 h UT to 1,500 h UT on 17th March 2015. On 17th March 2015, during the storm’s main phase, the selected stations showed GIX values ranging from 47.2 to 103.3 m TECU/km. On Recovery Day 19th March 2015, GIX readings range from 38.1 to 60 m TECU/km, this research plays a part in understanding ionospheric gradients in the equatorial and low latitudes, where it is applicable for improving Ground Based Augmentation Systems (GBAS) and GPS-aided GEO Augmented Navigation (GAGAN) effective for aircraft landing.
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Comparative analysis of pseudorange multipath mitigation performance using K-means and Fuzzy c-means clustering techniques

April 24, 2025

Valanon Uaratanawong, Chalermchon Satirapod

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Low satellite signal quality in urban areas is caused by multipath interference resulting from the abundance of various obstacles that limit satellite visibility performance, leading to poor satellite geometry and an increase in dilution of precision (DOP). The chance of encountering multipath significantly increases when receiving reflected signals from non-line-of-sight (NLOS) satellites, causing large positioning errors in pseudorange measurements. Enhanced identification of the multipath error source can improve positioning accuracy. This study first detected and then minimized multipath effects in pseudorange measurements using two unsupervised learning techniques – K-means and Fuzzy c-means (FCM) – which executed clustering across diverse multipath conditions and different combinations of GNSS, handled unlabeled quantitative data, and defined a certain number of clusters. Results indicated comparable performances of the K-means and FCM algorithms, with horizontal positioning accuracy improved by up to 35 % and vertical accuracy enhanced by up to 27 %.
Open Access
The usefulness of the MAFA method for smartphone precise positioning

April 23, 2025

Dawid Kwaśniak, Marcin Uradziński

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The paper presents smartphone GPS positioning results, using phase observations on the L1 frequency. In this research, we used one Huawei P30 Pro mobile phone, one Samsung S22 Ultra, and one geodetic receiver (Javad Triumph-1) acting as the reference receiver. Smartphones were placed on an aluminum base at an equal distance of 0.34 m from this receiver. Such a close distance was used to achieve identical observation conditions. The analysis was carried out from static GPS positioning, using the Modified Ambiguity Function Approach (MAFA) method. The short baselines were used during the tests. For the first part of the test, 5-min static sessions were performed for both smartphones. For post-processing kinematic (PPK), 1, 3, 5, and 10-s solutions achieved decimeter-level accuracy, while 30 and 60-s solutions provided centimeter-level accuracy for N and E on both smartphones. The results obtained from both smartphones are very promising. The authors proved that the MAFA method can be used for precise mobile phone positioning for short baselines.
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Influence of orbit and clock file diversity on GNSS ambiguity resolution

April 23, 2025

Heba K. Khayyal, Fawzi H. Zarzoura, Mahmoud El-Mewafi, Ashraf G. Shehata

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The continuous and accurate determination of positions, velocities, and time in Global Navigation Satellite Systems (GNSS) fundamentally relies on the precise knowledge of satellite orbits and clock information. These critical components, commonly referred to as orbit and clock files, serve as the backbone of GNSS systems such as GPS, GLONASS, Galileo, and others. They play an essential role in enabling high-accuracy positioning services for a wide range of applications, including navigation, mapping, scientific research, and time synchronization. A clear understanding of the principles and functionality of these orbit and clock files is paramount for comprehending the intricate mechanisms that underpin GNSS systems and their profound impact on positioning accuracy. This study provides a comprehensive exploration of GNSS systems with a particular focus on accuracy enhancement. The research primarily aims to elucidate the pivotal role played by a diverse array of organizations in supplying accurate and reliable orbit and clock files. By examining the multifaceted contributions and effects of these entities, the investigation unveils the complex processes through which GNSS accuracy is elevated to unprecedented levels. The findings underscore the indispensable contributions of these organizations in advancing the precision and reliability of GNSS technologies, thereby highlighting their critical importance in supporting the ever-growing demands of global positioning and timing applications.
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Recent estimates of crustal deformation and land subsidence in the Nile Delta, Egypt using GNSS-PPP datasets over 2012–2024

April 23, 2025

Gomaa M. Dawod, Essam M. Al-Krargy

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The Precise Point Positioning (PPP) technique has been utilized to process the Global Navigation Satellite Systems (GNSS) annual datasets at 24 stations in the Nile Delta region, Egypt from 2012 to 2024. The present study aims to present recent estimates of horizontal crustal deformation, vertical land movements, and the analysis of the International Terrestrial Reference Frame (ITRF) coordinate conversion between the two utilized ITRF frames in Egypt, namely ITRF2020 (epoch 2024) and ITRF2008 (epoch 2012). Based on the accomplished findings, it has been found that the land subsidence in the Nile Delta region ranges between −3.9 mm/year and 2.3 mm/year with an average of −1.5 ± 1.9 mm/year. Regarding the horizontal crustal movements, it is recognized that such crustal deformations vary between 25.8 mm/year to 27.6 mm/year with an average equals 27.0 ± 1.0 mm/year. In addition, the average direction of that deformation equals 38.6° ± 2.1°. Such results agree normally with those of other studies concerning the regional movements of the Nubia tectonic plate. The attained simple mathematical model describing the relationship between ITRF2024 and ITRF2008 frames shows that the average Cartesian displacement vector equals −0.312 m ± 0.026 m, 0.153 m ± 0.010 m, and 0.152 m ± 0.020 m in the X , Y , and Z directions respectively. Additionally, the velocities are −24 ± 2 mm/year, 12 ± 1 mm/year, and 12 ± 2 mm/year respectively.
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Comprehensive statistical analysis of scintillations on L-band signals from six GNSS constellations over low-latitude region

April 23, 2025

Kursheed Mohammed, Dattatreya Sarma Achanta, Lakshmanna Kuruva, Lakshmi Sreenivasa Reddy Dirisinapu

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Rapid variations in the amplitude and phase of signals travelling through the ionosphere of the Earth are known as ionospheric scintillations. This study presents the results of amplitude and phase scintillation characteristics at different L-band signal frequencies of six satellite constellations. The scintillation data was acquired using Septentrio’s PolaRx5S Ionospheric GNSS scintillation monitoring receiver located at a low latitude station. Samples of S 4 and σ φ data above standard threshold values with a 30° elevation mask for 293 days of the year 2023 are considered for analysis. Three aspects of scintillations are studied: i) statistics of their occurrences at different frequencies for all constellations ii) the correlation between amplitude and phase scintillation parameters for different frequencies iii) the temporal and spatial distributions of amplitude and phase scintillation at selected intensity levels. The results shows that about 70 % of total scintillation activity occurred during 20:30 to 22:59 LT. Further it is found that the signals coming in northern direction followed by southern direction are most affected compared to other directions indicating more ionospheric irregularities in those directions. This information is useful for identifying the least scintillation affected signals for position fixing.
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Automated gap and flush measurements between car parts assisted by a highly flexible and accurate robot system

April 23, 2025

Tobias Schröder, Volker Schwieger

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This research investigates the application of gap and flush measurements between structural car components as part of the quality assurance process in Mercedes-Benz production. The measuring tool, attached to a lightweight robot (LBR), is mounted on a driverless platform Kuka-Motion-Platform (KMP). The study collects measurement data during three critical production phases: car body construction, car varnishing, and body assembly. Throughout the entire production process, observing gap and flush values ensures the fulfilment of both functional and customer requirements. At the assembly line, two measurement approaches are used: Full Automatic Gap-Measuring Installations (SMA): These installations automatically measure gap and flush values. If errors are detected during measurement, the affected car bodies are diverted from the production lane. Hand-Held Instruments: Adjacent to the production line, two employees perform rework and repeat quality measurements to meet the required quality targets. Once corrections are successfully executed, the cars re-enter the production line. The study explores gap measurement using mobile measurement units (SME) in human-robot interaction (HRC). These mobile units, currently fixed in position, offer enhanced automation and flexibility within the production process. Future plans involve replacing the static SMA with systems like SME. Additionally, the research aims to develop a scalable and autonomous measuring system. Toward this goal, two main components from the SME the measurement devices and the LBR, are mounted on the KMP. The empirical determination of measurement device variance at the desired gap is achieved through propagation of uncertainty. In summary, this study contributes to the advancement of quality assurance practices in Mercedes-Benz car production by leveraging innovative measurement techniques and automation.
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Evaluation of mobile mapping point clouds in the context of height difference estimation

March 3, 2025

Markus Wagner, Berit Jost, Lasse Klingbeil, Heiner Kuhlmann

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In recent years, the usage of point cloud data for various mapping and other civil engineering tasks has become increasingly popular. The detailed acquisition of the environment forms a great advantage compared to point-wise methods using e.g. total station measurements. The major drawback is, that the uncertainty analysis of the measured points and accordingly the derived parameters is not straightforward. A variance propagation of the observations would not lead to plausible results, since the stochastic model is unknown in most of the cases. In this work, we present an empirical way to determine uncertainty information of the point cloud data captured by a mobile mapping system (MMS) related to height differences by using mainly the road surface, where the system drives on. Height differences between objects are often considered in the context of monitoring of land subsidence and engineering structures or mapping tasks. For the evaluation, height differences between points are analyzed, which differ in three major aspects from each other: the distances between the height observations, the environmental conditions, and the locations in the measurement volume of the system. Repeated measurements of the road surface and artificial targets are used to evaluate the precision of the height differences. Using reference values enables an analysis of the full uncertainty information. The results from two data sets show, that the environmental conditions severely influence the GNSS quality and consequently the precision of height differences decreases. Due to positive correlations between neighboring points, which are caused by the trajectory information, the height difference uncertainty increases concerning the traveled distance between the points. Because of remaining calibration errors, the location of the objects within the measurement volume of the profile laser scanner also influences the uncertainty of the height values and thereby also of height differences.
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Evaluation of PPP software performance for TEC estimation using IRI-2020, CODE, COSMIC, and SWARM with GNSS data

March 3, 2025

Reham Nagib, Mohamed A. Abdelfatah, Ashraf K. Mousa, Gamal S. EL-Fiky

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This study evaluates the performance of two Precise Point Positioning (PPP) software solutions, GAPS and GAMP, for estimating Vertical Total Electron Content (VTEC). Their outputs were compared against the International Reference Ionosphere (IRI) models, the Center for Orbit Determination in Europe (CODE) solutions, SWARM satellite data, and COSMIC-1 observations. The results demonstrate that GAPS achieves superior accuracy and reliability after initialization, with VTEC estimates closely aligning with CODE, IRI, COSMIC-1, and SWARM data. In contrast, GAMP, while exhibiting faster convergence, showed greater variability and a tendency to underestimate VTEC, especially under dynamic ionospheric conditions. Statistical analyses revealed that GAPS produced lower Root Mean Square (RMS) errors across stations, with values below 20 Total Electron Content Units (TECU) when compared to CODE, IRI and between 5 and 25 TECU when validated against COSMIC-1 and SWARM data. Conversely, GAMP’s RMS values reached up to 65 TECU, indicating lower precision. GAPS also showed smaller average and absolute differences, confirming its ability to capture localized ionospheric variations more effectively than GAMP and IRI models. A t -test analysis indicated no statistically significant differences between GAPS and CODE, IRI, SWARM, or COSMIC-1 for most stations, demonstrating the robustness of GAPS in representing ionospheric behavior. GAMP, however, often exhibited significant differences in VTEC estimates relative to these references. These findings demonstrate GAPS’s superior performance in ionospheric studies and VTEC estimation, underscoring the importance of choosing suitable PPP solutions and prepossessing for high-precision GNSS and atmospheric research.
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Spatiotemporal postseismic deformation due to the 2018 Palu-Donggala earthquake revealed the relative importance of viscoelastic relaxation and the afterslip distribution estimated from geodetic observations

February 14, 2025

Irma Yusiyanti, Fina Alfi Khasanah, Kautsar Rahtandi Trihandaru, Tattyana Wening Kalbuadi Prajardi, Cecep Pratama, Sidik Tri Wibowo

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The Palu region has attracted attention due to significant seismic activity, including a destructive earthquake in 2018. This study aims to investigate postseismic deformation following the 2018 Palu-Donggala earthquake using the Interferometric Synthetic Aperture Radar (InSAR) technique. We utilized Global Navigation Satellite System (GNSS) data to obtain the viscoelastic mechanism decay time. Therefore, we subtracted the viscoelastic relaxation signal to obtain spatiotemporal afterslip distribution inferred from the 2.5D InSAR observation based on the Steepest Descent Method (SDM). Our results suggest the viscoelastic mechanism is indispensable, with an optimal decay time of about 2 years after the earthquake. Based on the chi-square statistical test, the spatiotemporal afterslip model can explain the observation with good qualification. We found anomalies indicating non-decreasing slip, which is likely due to several factors, such as the presence of Slow Slip Events (SSE). These findings provide valuable insights regarding the potential for future earthquakes and have significant implications for disaster risk assessment in the Palu region and its surroundings.
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Research using GNSS (Global Navigation Satellite System) products – a comprehensive literature review

February 14, 2025

Aleksandra Maciejewska, Kamil Maciuk

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Global Navigation Satellite System (GNSS) products, including satellite orbit and clock corrections, ionospheric and tropospheric delay models, and multi-frequency data, are fundamental to modern geodesy and numerous scientific and industrial applications. The exploitation of these products facilitates the achievement of precise positioning, navigation, and timing (PNT) across a diverse range of fields, including transportation, geodesy, agriculture, and disaster management. Nevertheless, numerous challenges remain, including signal degradation due to multipath effects, atmospheric interference, and vulnerabilities to jamming and spoofing. Recent developments seek to address these limitations and enhance the utility of GNSS products. International collaboration, spearheaded by organizations such as the International GNSS Service (IGS), is crucial for standardizing and distributing GNSS products, facilitating global accessibility and addressing challenges such as climate monitoring and disaster resilience. This review emphasizes the indispensable role of GNSS products in advancing science and industry, highlights persistent challenges, and explores innovative solutions that promise to enhance their accuracy, resilience, and accessibility for addressing global needs.
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Application of GNSS-levelling for updating the base vertical network

February 5, 2025

Łukasz Borowski, Piotr Banasik, Kamil Maciuk

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This study explores the potential of GNSS-levelling to complement geometric levelling in the state levelling network, particularly outside the main lines. The Polish state levelling network plans to reduce the number of points from 40,000 to 16,000 during upcoming updates. GNSS-levelling is considered a cost-effective solution for filling gaps in the network, especially in rural areas. The experiment, commissioned by the Polish Head Office of Geodesy and Cartography, applied Polish geometric levelling accuracy criteria and tested them against GNSS-levelling. The goal was to develop a technique that an average surveying company could apply. The results showed that the initial hypothesis of GNSS-levelling’s suitability was not fully supported, primarily due to inconsistent vector repeatability. Accuracy could be improved by increasing the number of observation sessions or using specialized GNSS software while still maintaining cost-effectiveness. The experiment was conducted in an area where the state quasi-geoid model fits the levelling network with an accuracy of ±1 cm. Furthermore, the single vector solution (SVS) outperformed the each-to-each vector strategy (NET) in aligning with this network. Although challenges remain, GNSS-levelling demonstrates the potential and after refinement of techniques requirements, it is possible to obtain the main goal.
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Advancing magnetometer calibration: a sequential tri-axis approach

January 28, 2025

Omidreza Daneshmandi, Iman Hosseini, Arsalan Dabbagh, Iman Dehbozorgi, Ali Hosseinzadeh, Zahra Mehrmohammadi

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This paper presents a comparative study on the calibration of magnetometer sensors, focusing on three methods: the least square method, the ellipsoid fitting method, and a proposed sequential method. The effectiveness of the first two methods is investigated, and their results are compared with the outcomes achieved through the application of the sequential method. Practical data is utilized to demonstrate the advantages of the proposed method. Through this research, insights are provided into the performance and limitations of the least square and ellipsoid fitting methods, while highlighting the superior capabilities of the sequential method. The results show that the sequential method inherits the capabilities of both method and leads to a more reliable calibration.
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Impact of baseline length on uncertainty in static relative GNSS positioning

January 27, 2025

Satrio Muhammad Alif, Muhammad Ravid Erlando, Ongky Anggara, Misfallah Nurhayati

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Static relative Global Navigation Satellite Systems (GNSS) positioning is commonly used to achieve mm-level positioning uncertainty. However, few studies have examined the impact of baseline length to the positioning uncertainty. This study assesses 1,500 baselines across the five consecutive observation days and two plate motion inclusion options (15,000 baseline processing), to obtain the relationship between the baseline length and the positioning uncertainty. These baselines connect 25 International GNSS Stations (IGS) stations with the 60 Indonesia Continuously Operating Reference Stations (InaCORS) stations, continuous GNSS network in Indonesia. The 24-h GNSS data is processed using Bernese 5.2 to obtain daily coordinates solution in International Terrestrial Reference Frame 2014 (ITRF2014) with the uncertainty in the east/north/up component. Results show that longer baselines produce higher uncertainties, following an exponential trend. The east component has the lowest uncertainty due to the predominant east baseline azimuths. Baseline azimuths and plate motion considerations slightly influence uncertainty, but baseline length plays a much more significant role. Excluding plate motion noticeably increase uncertainty for baselines over 5,000 km. Specific uncertainty levels can be inferred from the exponential function, such as the baselines under 3,800 km are required for horizontal uncertainties under 3 mm. This exponential function also serves as a basis for selecting the constrained station in the GNSS data processing with the static relative GNSS positioning method.

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Issue 3

Special Issue: Joint International Symposium on Deformation Monitoring 2025

Special Issue: Deformation Monitoring

Special Issue: Deformation Monitoring

Special Issue: Deformation Monitoring

Special Issue on Multi-sensor Systems in Engineering Geodesy and Navigation

Journal of Applied Geodesy publishes special and thematic issues focussed on important and emerging topics in the field of study. The journal has established a rigorous process to ensure that any special issue manuscripts follow the same high-quality standards and peer review processes as regular manuscripts. For further information on the journal’s peer review policy please see the "Instructions for Authors".

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Editors-in-Chief
Hans-Berndt Neuner, TU Wien, Austria
Chris Rizos, University of New South Wales, Sydney, Australia

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Xiaoli Ding, The Hong Kong Polytechnic University, Hong Kong, China
Andreas Eichhorn, Technische Universität Darmstadt, Darmstadt, Germany
Naser El-Sheimy, The University of Calgary, Calgary, Canada
Linlin Ge, University of New South Wales, Sydney, Australia
Vassilis Gikas, National Technical University of Athens, Athens, Greece
Dorota Grejner-Brzezinska, The Ohio State University, Columbus, USA
Cheinway Hwang, Chiao Tung University, Hsinchu City, Taiwan
Allison Kealy, University of Melbourne, Victoria, Australia
Heiner Kuhlmann, Universität Bonn, Bonn, Germany
Hansjörg Kutterer, Bundesamt für Kartographie und Geodäsie, Frankfurt, Germany
Xiaolin Meng, University of Nottingham, Nottingham, United Kingdom
Gyula Mentes, Geodetic and Geophysical Research Institute of HAS, Sopron, Hungary
Hans-Berndt Neuner, Vienna University of Technology, Vienna, Austria
Wolfgang Niemeier, Technical University Braunschweig, Braunschweig, Germany
Alexander Reiterer, Fraunhofer Institute for Physical Measurement Techniques IPM, Freiburg, Germany
Guenther Retscher, Vienna University of Technology, Vienna, Austria
Volker Schwieger, University of Stuttgart, Stuttgart, Germany
Peter Teunissen, Delft University of Technology, The Netherlands and Curtin University of Technology, Perth, Australia
Andreas Wieser, ETH Zürich, Zürich, Schweiz
Caijun Xu, Wuhan University, Wuhan, Hubei, China

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March 22, 2007

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eISSN: 1862-9024

ISSN: 1862-9016

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