Towards the Integration of SAR Tomography and PSI for Improved Deformation Assessment in Urban Areas

Siddique, Muhammad Adnan; Hajnsek, Irena; Wegmüller, U.; Frey, Othmar

doi:10.5270/fringe2015.pp92

Cited by 5 publications

(7 citation statements)

References 23 publications

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“…The PSI solution, as shown in Figure 6, provides a good coverage over the viewed scene, which is typical with high resolution X-band interferometric imagery over urban areas such as Barcelona city [59,60]. The PS heights fit reasonably with actual 3-D structures, as shown for selected buildings in our earlier work in [26,27]. The PSI solution reveals deformation along the shoreline, which was partly observed in [59] as well.…”

Section: Interferometric Processingsupporting

confidence: 57%

“…In the absence of noise, for a given range-azimuth resolution cell, the mathematical model for SAR tomography (3-D SAR) can be written as [16,19,21,26,45]:…”

Section: Sar Tomography: Mathematical Modelmentioning

confidence: 99%

“…Additionally, differential SAR tomographic methods [23][24][25] allow a joint spatio-temporal inversion of the coherent scatterers in layover, i.e., the position along the elevation axis as well as the deformation velocity of the interfering scatterers are simultaneously estimated. Therefore, differential SAR tomography has been proposed as an add-on to PSI techniques to improve deformation sampling by resolving the scatterers in layover that are rejected in the PSI processing [26][27][28][29]. Inevitably, a detection strategy is again required to classify whether the detection of one or more scatterers in the same resolution cell is true or false.…”

Section: Introductionmentioning

confidence: 99%

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SAR Tomography as an Add-On to PSI: Detection of Coherent Scatterers in the Presence of Phase Instabilities

et al. 2018

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The estimation of deformation parameters using persistent scatterer interferometry (PSI) is limited to single dominant coherent scatterers. As such, it rejects layovers wherein multiple scatterers are interfering in the same range-azimuth resolution cell. Differential synthetic aperture radar (SAR) tomography can improve deformation sampling as it has the ability to resolve layovers by separating the interfering scatterers. In this way, both PSI and tomography inevitably require a means to detect coherent scatterers, i.e., to perform hypothesis testing to decide whether a given candidate scatterer is coherent. This paper reports the application of a detection strategy in the context of "tomography as an add-on to PSI". As the performance of a detector is typically linked to the statistical description of the underlying mathematical model, we investigate how the statistics of the phase instabilities in the PSI analysis are carried forward to the subsequent tomographic analysis. While phase instabilities in PSI are generally modeled as an additive noise term in the interferometric phase model, their impact in SAR tomography manifests as a multiplicative disturbance. The detection strategy proposed in this paper allows extending the same quality considerations as used in the prior PSI processing (in terms of the dispersion of the residual phase) to the subsequent tomographic analysis. In particular, the hypothesis testing for the detection of coherent scatterers is implemented such that the expected probability of false alarm is consistent between PSI and tomography. The investigation is supported with empirical analyses on an interferometric data stack comprising 50 TerraSAR-X acquisitions in stripmap mode, over the city of Barcelona, Spain, from 2007-2012.

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Section: Interferometric Processingsupporting

confidence: 57%

“…In the absence of noise, for a given range-azimuth resolution cell, the mathematical model for SAR tomography (3-D SAR) can be written as [16,19,21,26,45]:…”

Section: Sar Tomography: Mathematical Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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SAR Tomography as an Add-On to PSI: Detection of Coherent Scatterers in the Presence of Phase Instabilities

et al. 2018

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“…In [41] and [42], the extended phase model considers the nonlinear motion as a temporally sinusoidal variation alongside the linear component. The investigations presented in [43]- [45], however, explicitly include local temperature values to model phase variations related to thermal dilation; the results are provided for single scatterers only.…”

Section: A Related Workmentioning

confidence: 99%

Single-Look SAR Tomography as an Add-On to PSI for Improved Deformation Analysis in Urban Areas

Siddique¹,

Wegmüller

Hajnsek

et al. 2016

IEEE Trans. Geosci. Remote Sensing

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Persistent scatterer interferometry (PSI) is in operational use for spaceborne synthetic aperture radar (SAR)-based deformation analysis. A limitation inherently associated with PSI is that, by definition, a persistent scatterer (PS) is a single dominant scatterer. Therefore, pixels containing signal contributions from multiple scatterers, as in the case of a layover, are typically rejected in the PSI processing, which in turn limits deformation retrieval. SAR tomography has the ability to resolve layovers. This paper investigates the added value that can be achieved by operationally combining SAR tomography with a PSI approach toward the objective of improving deformation sampling in layover-affected urban areas. Different tomographic phase models are implemented and compared as regards their suitability in resolving layovers. Single-look beamforming-based tomographic inversion and a generalized likelihood ratio test (GLRT)-based detection strategy are used to detect single and double scatterers. The quantity of the detected scatterers is weighed against their quality as defined in terms of the phase deviation between the single-look complex (SLC) measurements and the tomographic model fit. The gain in deformation sampling that can be derived with tomography relative to a PSI-based analysis is quantitatively assessed, and alongside the quality of the scatterers obtained with tomography is compared with the quality of the PSs identified with a PSI approach. The experiments are performed on an interferometric stack of 50 TerraSAR-X stripmap images. The results obtained show that, although there is a tradeoff between the quantity and the quality of the detected scatterers, the tested SAR tomography approach leads to an improvement in deformation sampling in layover-affected areas.Index Terms-Deformation analysis in urban areas, persistent scatterer interferometry (PSI), synthetic aperture radar (SAR) tomography.

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“…SGLRTC compares the normalized energies of the potential scatterers against preselected thresholds. For details on SGLRTC the reader is referred to [29] and to our earlier works in [31], [79], [80].…”

Section: Scatterer Parameter Estimation and Detectionmentioning

confidence: 99%

A Case Study on the Correction of Atmospheric Phases for SAR Tomography in Mountainous Regions

Siddique

Strozzi

Hajnsek

et al. 2019

IEEE Trans. Geosci. Remote Sensing

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Synthetic aperture radar (SAR) tomography with repeat-pass acquisitions generally requires a priori phase calibration of the interferometric data stack by compensating for the atmosphere-induced phase delay variations. These variations act as a disturbance in tomographic focusing. In mountainous regions, the mitigation of these disturbances is particularly challenging due to strong spatial variations of the local atmospheric conditions and propagation paths through the troposphere. In this paper, we assess a data-driven approach to estimate these phase variations under a regression-kriging framework. The vertical stratification of the troposphere is modeled functionally while the impact of spatial turbulence is considered in a stochastic sense. The methodology entails an initial persistent scatterer interferometry (PSI) analysis. The atmospheric phases isolated for the persistent scatterers (PS) within the PSI processing are considered as samples of the 3-D distribution of the phase delay variations over the scene. These atmospheric phases are regressed against the spatial coordinates in map geometry at PS locations. In turn, kriging predictions are obtained at each location along the elevation profile where tomographic focusing is intended. A key point of this approach is that the requisite atmospheric corrections are incorporated within the tomographic focusing model. A case study has been performed on a data stack comprising 32 Cosmo-SkyMed stripmap images acquired over the Matter Valley in the Swiss Alps, in the summers of 2008-2013. The results show locally improved deformation sampling with tomographic methods compared to the initial PSI solution, primarily due to the improved phase calibration. In general, the work underscores the indispensability of height-dependent correction of atmospheric phases for SAR tomography. Index Terms-Synthetic aperture radar (SAR), SAR tomography, atmospheric phases, persistent scatterer interferometry (PSI), tomography in mountainous regions, SAR interferometry, deformation analysis in mountainous areas, radar interferometry Disclaimer: Graphical/textual differences may exist between this post-print and the final version published by IEEE which can be accessed at: https: //ieeexplore.ieee.org/document/8450633/.

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Towards the Integration of SAR Tomography and PSI for Improved Deformation Assessment in Urban Areas

Cited by 5 publications

References 23 publications

SAR Tomography as an Add-On to PSI: Detection of Coherent Scatterers in the Presence of Phase Instabilities

SAR Tomography as an Add-On to PSI: Detection of Coherent Scatterers in the Presence of Phase Instabilities

Single-Look SAR Tomography as an Add-On to PSI for Improved Deformation Analysis in Urban Areas

A Case Study on the Correction of Atmospheric Phases for SAR Tomography in Mountainous Regions

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