Joint Phase-Screen Estimation in Airborne Multibaseline SAR Tomography Data Processing

Airborne interferometric data is typically affected by phase distortions originated from subwavelength residual positioning uncertainties (phase screen) when acquired along different tracks. Available methods estimate the phase screen affecting stacks of multibaseline acquisitions, mainly by exploiting single interfograms separately. A novel method for the joint estimation of the multibaseline phase screens is proposed. The results of the implemented phase calibration are analyzed via a tomographic inversion, allowing to obtain a 3-D imaging estimating the vertical characteristics of the scene scattering. Specifically, we processed the multibaseline, fully polarized P-band synthetic aperture radar (SAR) data collected during the AfriSAR campaign in July 2015 over the Lopé tropical forests in Gabon, West Africa. Validation of the 3-D imaging results, supported by reference LiDAR (NASA LVIS) data, allowed demonstrating that the proposed joint estimation method overcomes the classical disjoint estimation solutions.