PolInSAR tomography for vertical profile retrieval of forest vegetation using spaceborne SAR data

Abstract

Forest height plays a crucial role to investigate the bio-physical parameters of forest and the terrestrial carbon. PolInSAR based inversion modeling has been successfully implemented on airborne and spaceborne SAR data. SAR tomography, which is an extension of cross-track interferometric processing is a recent approach to separate scatterers in cross range direction, thus generates its vertical profile. This study highlighted the potential of tomographic processing of fully polarimetric Radarsat-2 SAR system to retrieve backscatter power at different height levels. Eucalyptus patch of Haldwani forest division of Uttarakhand state in India was chosen as the test site. Since SAR tomography is a spectral estimation problem, Fourier transform and beamforming based spectral estimations were applied on the dataset to obtain their vertical profiles. Fourier severely suffered from high sidelobes which was drastically reduced by implementing beamforming by taking into account the multilooking effect at the expense of radiometric accuracy. Backscattered power values were found to be different at different height levels of the forest vegetation. Vertical profile for Fourier as well as beamforming were also retrieved.

UAVSAR Tomography for Vertical Profile Generation of Tropical Forest of Mondah National Park, Gabon

“…Apart from SAR tomography, three‐stage PolInSAR inversion is also a method for estimating the parameter like forest height profile estimation (Babu & Kumar, 2018; Joshi et al, 2016) of a forest. SAR tomography is an extension of 2‐D SAR imaging (range and azimuth plane) to 3‐D by forming an additional aperture (synthetic) in the direction of elevation utilizing the stack of multibaseline InSAR data sets resulting in a profile of height of target as a third dimension in the data (Reigber & Moreira, 2000).…”