A Three-Layer Scattering Model of the Slope Forest Area for Polarimetric SAR Interferometry

Abstract

Polarimetric SAR interferometry (PolInSAR) is a promising remote sensing technique for extracting forest height in which the random volume over ground (RVoG) model has been extensively applied to polarimetric interferometry SAR data for the retrieval of forest geophysical parameters. The complex interferometric coherence of the RVoG model was originally derived in a simplified way by neglecting some factors, like the terrain slope and the double bounce interaction with the stems or trunks. But in many cases, none of them should be ignored. Therefore, a slope three-layer scattering (STLS) model is proposed to correct the terrain distortion for forest parameters estimation in a sloping forest area. At the same time, this model separates the vertical structure of forest into three layers: ground, tree-trunk and the canopy layer which account for the simultaneous effects of three scattering components on complex coherence. A significant model complexity reduction is achieved by aligning the reference frame along the local terrain slope and changing the corresponding radar geometrical configuration. The STLS model provides a better understanding of microwave scattering process in the terrain slope area compared to traditional RVoG model.