Polarimetric SAR Interferometry makes possible a detailed analysis of the volumetric scattering processes present in microwave scattering in case of forest areas. In previous contributions, the authors, under the hypothesis of the RVoG coherent scattering model, developed a process for the direct extraction of the ground topography. In this paper, the authors present a generalization of this technique allowing to determine a set of scattering mechanisms making possible an optimization process for the estimation of the ground topography. The applicability of this technique, in case of X-band polarimetric SAR interferometric data, is explored considering data obtained in the frame of the TanDEM-X mission.