Abstract
Conventional differential synthetic aperture radar tomography (D-TomoSAR) can only capture the scatterers’ one-dimensional (1-D) deformation information along the line of sight (LOS) of the synthetic aperture radar (SAR), which means that it cannot retrieve the three-dimensional (3-D) movements of the ground surface. To retrieve the 3-D deformation displacements, several methods have been proposed; the performance is limited due to the insufficient sensitivity for retrieving the North-South motion component. In this paper, an improved D-TomoSAR model is established by introducing the scatterers’ 3-D deformation parameters in slant range, azimuth, and elevation directions into the traditional D-TomoSAR model. The improved D-TomoSAR can be regarded as a multi-component two-dimensional (2-D) polynomial phase signal (PPS). Then, an effective algorithm is proposed to retrieve the 3-D deformation parameters of the ground surface by the 2-D product high-order ambiguity function (PHAF) with the relax (RELAX) algorithm. The estimation performance is investigated and compared with the traditional algorithm. Simulations and experimental results with semi-real data verify the effectiveness of the proposed signal model and algorithm.
Highlights
Differential synthetic aperture radar (SAR) tomography (D-TomoSAR) [1,2] is a kind of multi-baseline SAR processing framework that allows the joint resolution capability of multiple scatterers’ velocities and elevations in the same range-azimuth cell through a two-dimensional (2-D)baseline-time spectral estimation
D-TomoSAR is widely used in mapping and monitoring the infrastructure deformation and ground subsidence caused by the over-pumping of groundwater or mining
The observation geometry of conventional D-TomoSAR is shown in Figure 1, where X represents the ground-range direction, Y is the azimuth direction, Z is the vertical height direction, r is the reference slant range direction along the line of sight (LOS) of the radar, and s is the elevation direction orthogonal to the slant range-azimuth plane
Summary
Differential synthetic aperture radar (SAR) tomography (D-TomoSAR) [1,2] is a kind of multi-baseline SAR processing framework that allows the joint resolution capability of multiple scatterers’ velocities and elevations in the same range-azimuth cell through a two-dimensional (2-D). Results of existing methods for retrieving the 3-D deformation show that the higher the diversity of the geometric configuration (the satellite heading angle and incidence angle of antenna) of the combined SAR data is, the more accurate the North-South retrieval results will be [12] This provides an effective way to improve the accuracy of North-South deformation retrieval. The SuperSAR [12,16] and BiDiSAR [17] are proposed to improve the accuracy of the deformation retrieval in the North-South direction by increasing the squint angle of SAR imaging in D-InSAR. An improved D-TomoSAR signal model is proposed by introducing the squint angle of SAR imaging into the traditional D-TomoSAR model to achieve a higher accuracy for North-South deformation estimation.
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