Journal of Applied Geodesy最新文献

{"title":"Investigation of the trade-off between the complexity of the accelerometer bias model and the state estimation accuracy in INS/GNSS integration","authors":"Gilles Teodori, H. Neuner","doi":"10.1515/jag-2022-0034","DOIUrl":"https://doi.org/10.1515/jag-2022-0034","url":null,"abstract":"Abstract The integration of Inertial Navigation Systems and Global Navigation Satellite Systems (GNSS) represents the core navigation unit for mobile platforms in open sky environments. A realistic assessment of the accuracy of the navigation solution depends on the accurate modelling of inertial sensor errors. Sensor noise and biases contribute most to short-term navigation errors. For the latter, different models can be used, varying in complexity. This paper investigates how the use of two different models for the accelerometer bias affects the accuracy of the state estimate in an extended Kalman filter. For this purpose, the Allan variance technique is applied to a data sequence from a specific inertial sensor to identify and quantify the underlying noise processes. The estimated noise parameters are used to characterise a bias model for the accelerometers that in addition to the static bias model takes non-white noise processes of the inertial sensor under investigation into account. This detailed accelerometer bias model is compared to a classical modelling approach that only considers static biases. Both approaches are evaluated based on simulation studies for continuous and intermittent GNSS coverages. The results show no significant difference between the two modelling approaches in terms of horizontal position and attitude precision. Furthermore, the correctness of the accelerometer bias estimates is not significantly affected by the modelling approach. All in all, it can be concluded that a detailed bias model of the accelerometers does not outperform the classical modelling approach.","PeriodicalId":45494,"journal":{"name":"Journal of Applied Geodesy","volume":"17 1","pages":"181 - 195"},"PeriodicalIF":1.4,"publicationDate":"2023-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45383538","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High-precision intermode beating electro-optic distance measurement for mitigation of atmospheric delays","authors":"Pabitro Ray, D. Salido-Monzú, A. Wieser","doi":"10.1515/jag-2022-0039","DOIUrl":"https://doi.org/10.1515/jag-2022-0039","url":null,"abstract":"Abstract High-precision electro-optic distance measurement (EDM) is essential for deformation monitoring. Although sub-ppm instrumental accuracy is already feasible with state-of-the-art commercial technology, the practically attainable accuracy on distances over more than a few hundred meters is limited by uncertainties in estimating the integral refractive index along the propagation path, which often results in measurement errors of several ppm. This paper presents a new instrumental basis for high-accuracy multispectral EDM using an optical supercontinuum to enable dispersion-based inline refractivity compensation. Initial experiments performed on two spectrally filtered bands of 590 and 890 nm from the supercontinuum show measurement precision better than 0.05 mm over 50 m for an acquisition time of around 3 ms on the individual bands. This represents a comparable performance to our previously reported results on 5 cm by over a range of 3 orders of magnitude longer, which can still be improved by increasing the acquisition time. The preliminary results indicate a relative accuracy of about 0.1 mm at 50 m on each wavelength. Improvement is possible by calibration and by implementing a self-reference scheme that mitigates slow drifts caused by power-to-phase coupling. The results reported herein thus indicate that the presented approach can be further developed for achieving sub-ppm accuracy of refractivity compensated distance measurements on practically useful ranges and under outdoor conditions.","PeriodicalId":45494,"journal":{"name":"Journal of Applied Geodesy","volume":"17 1","pages":"93 - 101"},"PeriodicalIF":1.4,"publicationDate":"2023-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43696466","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Image segmentation of breakwater blocks by edge-base Hough transformation","authors":"F. Soares, Vinicius Barbon","doi":"10.1515/jag-2022-0044","DOIUrl":"https://doi.org/10.1515/jag-2022-0044","url":null,"abstract":"Abstract A rubble mound breakwater (BW) is a coastal engineering structure built for purposes of harbor protection in areas with severe wave regimes. Block displacements can lead to a structure weakening, making the harbor more vulnerable to waving hazard. During the phase of BW design/rehabilitation the effectiveness evaluation of both the shape and the protective elements is made throughout 3D scale models, built inside wave basins or wave flumes. The experiment consists of simulating the impact of the swell on the model. During the process, 3D point cloud (PC) data is recorded with depth sensors, or later generated by photogrammetry from image data. Surface changes are obtained by comparing PCs, with the estimation of depth differences. However, inaccurate face delimitation on PCs may lead to less conclusive results of blocks’ location and motion. In this study, it is proposed an edge-based image segmentation method, based on the Hough transformation algorithm, in order to obtain the straight edges of the block’s faces in images of breakwater models. By crossing each resulting polygonal region with the PC depth data of the block, a regular plane surface can be adjusted to the 3D points, from which the block’s center point can be geometrically estimated. For this study RGB and PC data regions were selected from a scanned BW model, built with small cubic concrete blocks. The results obtained reinforce the positive contribution that the proposed image segmentation methodology can provide, regarding the improvement of displacement accuracy and spending time analysis, in BW monitoring work.","PeriodicalId":45494,"journal":{"name":"Journal of Applied Geodesy","volume":"17 1","pages":"131 - 137"},"PeriodicalIF":1.4,"publicationDate":"2022-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42456571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A mobile robot for monitoring floor flatness in real-time","authors":"C. Naab","doi":"10.1515/jag-2022-0046","DOIUrl":"https://doi.org/10.1515/jag-2022-0046","url":null,"abstract":"Abstract As part of the structural inspection, compliance with the specified flatness tolerances according to DIN (in particular DIN 18202:2019-07) has to be checked. Today, the monitoring of the flatness is carried out mainly with levelling instruments and tacheometers. However, these measuring methods are time-consuming, as stacking out the measuring grid and capturing the heights are performed manually. In addition, the data evaluation must be done in a separate work step. Therefore, we developed the mobile robot RITA for height measurement in combination with a stationary tacheometer. Now, the entire process of flatness control is carried out automatically, and heights are recorded reliably in real-time. For practicality, we developed a compact design of the mobile robot in combination with hardware modules. Our reflector tracking unit makes it possible to follow the reflector on the robotic platform in order to maintain the line of sight to the tacheometer. Furthermore, our mechanical pendulum unit ensures that the height measurement is always carried out vertically, even if the robot itself is tilted. Initial practical tests have shown that the high demands on the robotic platform are met and that the implementation of the flatness control can be automated. For that, investigations concerning the location accuracy of the robot were carried out, and the height measurement was validated. It turns out, that demands in the lowest millimeter range are fulfilled. Overall, these tests showed the enormous gain in performance due to the newly developed height measurement robot compared to the previous slow, complex, and tiring manual process.","PeriodicalId":45494,"journal":{"name":"Journal of Applied Geodesy","volume":"17 1","pages":"109 - 117"},"PeriodicalIF":1.4,"publicationDate":"2022-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43594770","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ionospheric scintillation characteristics from GPS observations over Malaysian region after the 2011 Valentine’s day solar flare","authors":"Aramesh Seif, S. Panda","doi":"10.1515/jag-2022-0053","DOIUrl":"https://doi.org/10.1515/jag-2022-0053","url":null,"abstract":"Abstract Ionospheric scintillations due to plasma irregularities can severely affect the modern dynamic and technological systems whose operations rely on satellite-based navigation systems. We investigate the occurrence of ionospheric scintillation in the equatorial and low latitude region over Malaysia after the 2011 Valentine’s Day solar flare. A network of three Global Ionospheric Scintillation and Total Electron Content Monitor (GISTM) GSV4004B receivers with increasing latitudes from the magnetic equator were used to monitor ionospheric TEC, rate of change of TEC index (ROTI), and amplitude (S4) as well as phase (σ φ) scintillation indices. The results show a simultaneous sudden rise in S4 and σ φ along with a significant depletion of TEC at all three locations. However, the largest enhancement of scintillation indices accompanying a substantial TEC depletion is observed at the farthest low latitude station (UNIMAS) from the equator with values around 0.5, 0.3 rad, and 1 TECU, respectively. The corresponding values at the near-equatorial station (Langkawi; 0.4, 0.2 rad, and 3 TECU) and intermediate station (UKM; 0.45, 0.3 rad, and 5 TECU) are examined along with ROTI variations, confirming the simultaneous occurrence of kilometer-scale and sub kilometer scale irregularities during 17 and 18 February 2011. The radiation effects of the solar flare on the ionosphere were prominently recognized at the local nighttime hours (around 14:00 to 17:00 UT) coinciding with the equatorial prereversal enhancement (PRE) time to seed the equatorial plasma bubbles (EPBs) enhancement that resulted in ionospheric irregularities over the low latitudes. The significant TEC depletion seen in the signals from selected GPS satellites (PRNs 11, 19, 23, and 32) suggests plausible degradation in the performance of GPS-based services over the Malaysian region. The study provides an effective understanding of the post-flare ionospheric irregularities during an episode of minor geomagnetic storm period and aligns with the efforts for mitigating the scintillation effects in space-based radio services over low latitudes.","PeriodicalId":45494,"journal":{"name":"Journal of Applied Geodesy","volume":"17 1","pages":"79 - 90"},"PeriodicalIF":1.4,"publicationDate":"2022-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43263305","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A real-time algorithm for continuous navigation in intelligent transportation systems using LiDAR-Gyroscope-Odometer integration","authors":"Tarek Hassan, T. Fath-Allah, M. Elhabiby, Alaa ElDin Awad, M. El‐Tokhey","doi":"10.1515/jag-2022-0022","DOIUrl":"https://doi.org/10.1515/jag-2022-0022","url":null,"abstract":"Abstract Real-time positioning in suburban and urban environments has been a challenging task for many Intelligent Transportation Systems (ITS) applications. In these environments, positioning using Global Navigation Satellite Systems (GNSS) cannot provide continuous solutions due to the blockage of signals in harsh scenarios. Consequently, it is intrinsic to have an independent positioning system capable of providing accurate and reliable positional solutions over GNSS outages. This study exploits the integration of Light Detection and Ranging (LiDAR), gyroscope, and odometer sensors, and a novel real-time algorithm is proposed for this integration. Real field data, collected by a moving land vehicle, is used to test the presented algorithm. Three simulated GNSS outages are introduced in the trajectory such that each outage lasts for five minutes. The results show that using the proposed algorithm can achieve a promising navigation performance in urban environments. In addition, it is shown that the denser environments, that existed over the second and third outages, can provide better positioning accuracies as more features are extracted. The horizontal errors over the first outage, with less density of surroundings, reached 7.74 m (0.43%) error with a mean value of 3.15 m. Moreover, the horizontal errors in the denser environments over the second and third outages reached 4.97 m (0.28%) and 3.99 m (0.23%), with mean values of 2.25 m and 1.89 m, respectively.","PeriodicalId":45494,"journal":{"name":"Journal of Applied Geodesy","volume":"17 1","pages":"65 - 77"},"PeriodicalIF":1.4,"publicationDate":"2022-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46041154","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"EDM-GNSS distance comparison at the EURO5000 calibration baseline: preliminary results","authors":"K. Wezka, L. García-Asenjo, D. Próchniewicz, S. Baselga, R. Szpunar, P. Garrigues, J. Walo, Raquel Luján","doi":"10.1515/jag-2022-0049","DOIUrl":"https://doi.org/10.1515/jag-2022-0049","url":null,"abstract":"Abstract At the Pieniny Klippen Belt in Poland, the novel primary reference baseline EURO5000 is required as part of the European Research project GeoMetre to both validate refractivity-compensated EDM prototypes and investigate the metrological traceability of GNSS-based distances. Since the aimed uncertainty is 1 mm at 5 km (k = 2), the design, construction, and validation must be carefully prepared to fulfil the high standards of the GeoMetre field campaigns which are planned to be carried out in May 2022. This contribution describes the main features of the EURO5000 and presents the results of the preliminary validation which includes a first comparison between the results obtained by using precise currently available EDMs as well as GNSS techniques following the standard GNSS geodetic processing algorithms, on the one hand, and the improved GNSS-Based Distance Meter (GBDM+) approach developed at UPV, on the other hand. The preliminary validation presented in this contribution also permits (1) to detect potential problems in the use of the baseline such as potential geodynamic problems, atmospheric refraction or multipath limitations, (2) to produce a set of reliable results, and (3) to pave the way for the final field comparisons between the novel EDMs and the GBDM+ approach. The result of this metrological experiment may significantly contribute to overcome the limitations of current high-precision deformation monitoring applications that require their scale to be consistent with the SI-metre within 0.1 ppm in several km.","PeriodicalId":45494,"journal":{"name":"Journal of Applied Geodesy","volume":"17 1","pages":"101 - 109"},"PeriodicalIF":1.4,"publicationDate":"2022-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41358640","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Forecasting post-earthquake rockfall activity","authors":"Michael J. OlsenM.J. Olsen, C. Massey, B. Leshchinsky, J. Wartman, A. Senogles","doi":"10.1515/jag-2022-0045","DOIUrl":"https://doi.org/10.1515/jag-2022-0045","url":null,"abstract":"Abstract Important infrastructure such as highways or railways traverse unstable terrain in many mountainous and scenic parts of the world. Rockfalls and landslides result in frequent maintenance needs, system unreliability due to frequent closures and restrictions, and safety hazards. Seismic activity significantly amplifies these negative economic and community impacts by generating large rockfalls and landslides as well as weakening the terrain. This paper interrogates a rich database of repeat terrestrial lidar scans collected during the Canterbury New Zealand Earthquake Sequence to document geomorphic processes as well as quantify rockfall activity rates through time. Changes in the activity rate (spatial distribution) and failure depths (size) were observed based on the Rockfall Activity Index (RAI) morphological classification. Forecasting models can be developed from these relationships that can be utilized by transportation agencies to estimate increased maintenance needs for debris removal to minimize road closures from rockfalls after seismic events.","PeriodicalId":45494,"journal":{"name":"Journal of Applied Geodesy","volume":"17 1","pages":"171 - 179"},"PeriodicalIF":1.4,"publicationDate":"2022-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42619642","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Supervoxel-based targetless registration and identification of stable areas for deformed point clouds","authors":"Yihui Yang, V. Schwieger","doi":"10.1515/jag-2022-0031","DOIUrl":"https://doi.org/10.1515/jag-2022-0031","url":null,"abstract":"Abstract Accurate and robust 3D point cloud registration is the crucial part of the processing chain in terrestrial laser scanning (TLS)-based deformation monitoring that has been widely investigated in the last two decades. For the scenarios without signalized targets, however, automatic and robust point cloud registration becomes more challenging, especially when significant deformations and changes exist between the sequence of scans which may cause erroneous registrations. In this contribution, a fully automatic registration algorithm for point clouds with partially unstable areas is proposed, which does not require artificial targets or extracted feature points. In this method, coarsely registered point clouds are firstly over-segmented and represented by supervoxels based on the local consistency assumption of deformed objects. A confidence interval based on an approximate assumption of the stochastic model is considered to determine the local minimum detectable deformation for the identification of stable areas. The significantly deformed supervoxels between two scans can be detected progressively by an efficient iterative process, solely retaining the stable areas to be utilized for the fine registration. The proposed registration method is demonstrated on two datasets (both with two-epoch scans): An indoor scene simulated with different kinds of changes, including rigid body movement and shape deformation, and the Nesslrinna landslide close to Obergurgl, Austria. The experimental results show that the proposed algorithm exhibits a higher registration accuracy and thus a better detection of deformations in TLS point clouds compared with the existing voxel-based method and the variants of the iterative closest point (ICP) algorithm.","PeriodicalId":45494,"journal":{"name":"Journal of Applied Geodesy","volume":"17 1","pages":"161 - 170"},"PeriodicalIF":1.4,"publicationDate":"2022-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48815360","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fitting a triaxial ellipsoid to a set of quasi-selenoidal points","authors":"E. Kontou, G. Panou","doi":"10.1515/jag-2022-0024","DOIUrl":"https://doi.org/10.1515/jag-2022-0024","url":null,"abstract":"Abstract The aim of this work is the determination of the parameters of the triaxial ellipsoid of the Moon, as derived from a quasi-selenoid model. After a detailed description of various quasi-selenoid models of the lunar gravity field, which were proposed in the last twenty years, we prepare suitable data sets of three-dimensional Cartesian coordinates. The mathematical model adopted is the general (polynomial) equation of an ellipsoid functionally related to the nine unknowns: the coordinates of the ellipsoid center, the three rotation angles and the three ellipsoid semiaxes. Furthermore, we adopt mathematical models for one special and two degenerate cases of the triaxial ellipsoid. We implement the least-squares method of indirect observations and we derive results for eighteen data sets of quasi-selenoidal points. From the results, we report the values of the semiaxes of the triaxial ellipsoid of fitting with three unknowns, for the model GL0660B, to be 1,738,256.3 ± 0.2 m, 1,738,023.1 ± 0.2 m and 1,737,603.2 ± 0.2 m, while the other unknowns remain insignificant. This triaxial ellipsoid leads to the improvement in the RMS value of the height anomaly at about 12 per cent in comparison to the oblate spheroid.","PeriodicalId":45494,"journal":{"name":"Journal of Applied Geodesy","volume":"17 1","pages":"53 - 63"},"PeriodicalIF":1.4,"publicationDate":"2022-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43011716","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}