Tree height estimation using an airborne L-band polarimetric interferometric SAR

Interferometric phase difference among the SAR and trees, composed of trunks, branches, and canopies, provides an information related to trees heights and structures at a given polarization. Vertical polarization (like) is sensitive on the vertical structure and the horizontal pot. (like) for the horizontal one. Cross pol. is sensitive to the inclined branches (inclined cylinder depolarizes the incoming signal). Thus, combination of the polarization based phase measurement might give tree height distribution and the structures when a scattering model that simulates electromagnetic signal interaction with the trees is used. Interferometric sensitivity to the height decreases with slant range and signal to noise ratio and increases with the baseline and the spaceborne sensor has some difficulty. Thus, we used the NASDA-CRL´s airborne L-band Polarimetric Interferometric Synthetic Aperture Radar (PISAR), and its acquired polarimetric SAR interferometry datasets. Test site was the Tottori Dune and its surrounding area, where pine trees were planted and the characteristics were well known. Coherence and the phase differences obtained by the interferometric analysis were evaluated. As a result, we could estimate the tree height distribution if the polarimetric SAR images (co-pol and cross-pot) are acquired with larger baselines and smaller slant ranges. Quantitative evaluation is required to relate the phase center differences and the tree types and the polarization combinations