Assessment of Scattering Mechanism of Polarimetric SAR Signal From Mountainous Forest Areas

Abstract

International audienceThis study aims to understand the effects of the topographic slope variation on the vegetation backscattering characteristics of polarimetric imaging radar. Most of the previous studies in modeling microwave backscattering signatures of vegetated area have been carried out over relatively flat areas. In order to model vegetation scattering mechanisms of mountainous forests, this paper presents an improvement of the radiative transfer model that accounts for the tilted scattering surface beneath a forest canopy. An L-band polarimetric synthetic aperture radar (SAR) data set acquired by the NASA/Jet Propulsion Laboratory Airborne SAR system was used to test and to assess the vegetation scattering model for a sloping forest area. Experimental result shows the proposed model to be adequate for evaluating slope-induced changes in microwave scattering mechanisms

The Effect of Topography on Target Decomposition of Polarimetric SAR Data

“…In mountainous forests, local topographic variations can lead to changes in the microwave scattering mechanisms [11][12][13]. Particularly, it has been reported that, among the radar backscattered signals, direct ground and vegetation-ground interactions can be significantly affected by the presence of topography [13].…”

“…Particularly, it has been reported that, among the radar backscattered signals, direct ground and vegetation-ground interactions can be significantly affected by the presence of topography [13]. Consequently, the validity of the scattering models used in the target decomposition and relating slope-induced errors in the output of target decomposition techniques should be carefully evaluated in sloping forest areas.…”

“…In this study, the effect of topographic slope variations on the model-fitting-based target decomposition method is evaluated on the basis of the simulated target matrix by the microwave vegetation scattering model proposed in [13]. In the following section, a brief review of the target decomposition methods is presented.…”

“…The experimental analysis of topography effects on the target decomposition methods is carried out by using the simulated coherency matrix obtained from vegetation scattering model of sloping terrain [13]. This vegetation scattering model is based on the first-order solution of the radiative transfer model and considers a tilted scattering surface beneath forest canopy.…”

“…Densities, dimensions and orientation distributions for each layer are specified as summarized in Table 1. The orientation of vegetation constituents is characterized by the Eulerian polar angle [13]. It is assumed to be uniformly distributed within the angular boundaries listed in Table 1.…”