Special Issue “Synthetic Aperture Radar (SAR) Techniques and Applications”

Bovenga, F.

doi:10.3390/s20071851

Cited by 24 publications

(14 citation statements)

References 19 publications

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“…Throughout the phase information mapped on the interferograms, deformations due to large earthquakes can be detected and main faults revealed. Some of the studies mentioned in [2] use SAR interferometry (InSAR) to detect the displacement related to land subsidence [3], earthquakes ( [4][5][6]), highway deformation [7] and similar land displacements ( [8], anthropogenic deformation phenomenon [9,10]), or urban change ( [11,12]). It has also been proved by a recent study [13] that InSAR measurements produce noise, but the noise can be reduced without the loss of significant data information by applying the processing techniques.…”

Section: Introductionmentioning

confidence: 99%

Coseismic Ground Displacement after the Mw6.2 Earthquake in NW Croatia Determined from Sentinel-1 and GNSS CORS Data

et al. 2021

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At the very end of the year 2020, on 29 December, a hazardous earthquake of Mw = 6.2 hit the area of Petrinja and its surroundings, in the NW of Croatia. The earthquake was felt across the area of 400 km, leaving an inconceivable damage in the vicinity of the epicenter, devastated towns and ruined lives. In order to map the spreading of earthquake waves and to determine the coseismic ground displacement after the mainshock, we have analyzed open satellite radar images of Sentinel-1 and the GNSS data from the nearest CORS station related to the epicenter, along with the seismic faults. In this paper, we addressed and mapped the displacement linear surface ruptures detected by the SAR interferometry. The results show the vertical ground displacement to the extent of −12 cm in the southern area and up to 22 cm in the north-western part of a wide area struck by the earthquake impact, related to the epicenter. Subsidence and uplift in a range of ±5 cm over a wider affected area indicate a spatial extent and hazardous impact made by the earthquake. The ground displacement of 30 cm to the West and 40 cm to the East has been identified considering the intersection of Pokupsko and Petrinja strike-slip fault system in the seismic zone of Pannonian basin. Accordingly, we obtained matching results of 5 cm south-easting shift and −3 cm subsidence on Sisak GNSS CROPOS station, addressing the tectonic blocks movement along the activated complex fault system. The results compared with the geology data confirm the existence of two main faults; the Pokupsko and the Petrinja strike-slip faults and interpret the occurrence of secondary post-seismic events over the observed area.

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Section: Introductionmentioning

confidence: 99%

Coseismic Ground Displacement after the Mw6.2 Earthquake in NW Croatia Determined from Sentinel-1 and GNSS CORS Data

et al. 2021

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“…In all of these cases, quick, precise, and interpretable change detection is critical to deriving timely information and properly reacting in the subsequent follow-up. A synthetic aperture radar (SAR) sensor is extensively used in numerous areas [ 7 ] to obtain change maps since it is not affected by the weather, light, or flight altitude [ 8 , 9 ]. These images typically form the function for actions such as those listed above.…”

Section: Introductionmentioning

confidence: 99%

Comparative Analyses of Unsupervised PCA K-Means Change Detection Algorithm from the Viewpoint of Follow-Up Plan

Kılıç

Nielsen

2022

Sensors

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In this study, principal component analysis and k-means clustering (PCAKM) methods for synthetic aperture radar (SAR) data are analyzed to reduce the sensitivity caused by changes in the parameters and input images of the algorithm, increase the accuracy, and make an improvement in the computation time, which are advantageous for scoring in the follow-up plan. Although there are many supervised methods described in the literature, unsupervised methods may be more appropriate in terms of computing time, data scarcity, and explainability in order to supply a trustworthy system. We consider the PCAKM algorithm, which is used as a benchmark method in many studies when making comparisons. Error metrics, computing times, and utility functions are calculated for 22 modified PCAKM regarding difference images and filtering methods. Various images with different characteristics affect the results of the configurations. However, it is evident that the PCAKM becomes less sensitive and more accurate for both the overall results and image results. Scoring by utilizing these results and other map information is a gap and innovation. Obtaining a change map in a fast, explainable, more robust and less sensitive way is one of the aims of our studies on scoring points in the follow-up plan.

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“…However, large size devices are not convenient for wearable systems. In this context, synthetic aperture radar (SAR) techniques are of great relevance to improve the cross-range resolution and accurately determine the location of targets [18]. This technique involves the movement of an antenna along certain path [19].…”

Section: Introductionmentioning

confidence: 99%

System Based on Compact mmWave Radar and Natural Body Movement for Assisting Visually Impaired People

et al. 2021

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The aim of this paper is to show how compact mmWave radar systems, attached to a person, can take advantage of their movements, in order to significantly improve the image resolution by means of synthetic aperture radar (SAR) techniques. Thus, high resolution imaging becomes possible even with tiny on-chip systems, opening up a horizon of possibilities to assist visually impaired people. The approach is illustrated for movements in terms of arm swings. For this purpose, it is firstly shown that the information from an inertial measurement unit (IMU) can be used to provide a trajectory estimation, which is enough to apply synthetic aperture radar processing. As a consequence, the resolution of the radar is greatly improved when compared with that achieved considering a single position. In order to avoid the continuously growing position error, commonly observed in dead-reckoning systems relying just on IMU, zero velocity updates (ZUPT) will be systematically applied. For doing so, two different zero velocity detectors (ZVD) are considered, one based on acceleration data and other on velocity estimation. Although the positioning information is extracted from the IMU, demonstrating the enhanced obstacle detection capabilities obtained with this approach, other sensors that can be carried by a person and that are capable of providing trajectory estimations to combine measurements acquired with compact mmWave radars could have been used. The system is tested using different targets and a good performance comparable to the one achieved by using a high accuracy reference positioning system is attained. The compactness of the system enables the possibility of using it as a wearable device, e.g., attached to the wrist. This shows that an IMU is enough for tracking relatively simple movements, though more complex positioning systems can be used for more general actions.INDEX TERMS Freehand imaging, visually impaired, inertial measurement unit, mmWave radar, synthetic aperture radar (SAR), wrist mounted imager, zero velocity detectors (ZVD).

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Special Issue “Synthetic Aperture Radar (SAR) Techniques and Applications”

Cited by 24 publications

References 19 publications

Coseismic Ground Displacement after the Mw6.2 Earthquake in NW Croatia Determined from Sentinel-1 and GNSS CORS Data

Coseismic Ground Displacement after the Mw6.2 Earthquake in NW Croatia Determined from Sentinel-1 and GNSS CORS Data

Comparative Analyses of Unsupervised PCA K-Means Change Detection Algorithm from the Viewpoint of Follow-Up Plan

System Based on Compact mmWave Radar and Natural Body Movement for Assisting Visually Impaired People

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