Analysis of Orientation Effects of Crop Vegetation Volumes by Means of SAR Tomography at Different Frequencies

Abstract

Synthetic aperture radar (SAR) tomography is a powerful approach to investigate, widely model free, the relationship between 3-D radar backscattering and physical structure of agricultural vegetation which is not fully understood yet. In this paper, the focus is set on the polarimetric characterization of scattering differences and the detection of orientation effects (i.e. differential extinction) on backscattering of the vegetation layer as a function of species, time and frequency. This is done by separating the ground and volume scattering contributions (applying a coherent layer cancellation to the multi-baseline (MB) multi-polarimetric SAR data stack). To assess the presence of orientation effects, a distance measure is applied to the volume-only coherences to decide if they fit the random volume or the general oriented volume model. The experimental analysis and validation is performed on data acquired by the DLR airborne sensor F-SAR.