Recent studies have shown that the volumetric scatterers of different canopy types warranted varying scattering models, which feature different orientation and shape characteristics. In this paper, we explore the possibility of estimating the orientation and shape parameters from POLSAR observations. Both the orientation and shape parameters of the canopy are defined by a cloud of spheroids with independent orientation and shape distributions. The respective parameters clearly express themselves in the circular polarization basis in which we derive the analytic solutions. Applying the estimation to POLSAR data, we demonstrate these parameters capable of characterizing the canopy scatterers, providing a consistent physical interpretation of the target scattering mechanisms and generating a fine-grained initialization for Wishart classifications of vegetation and forest targets.