Modelled polarimetric backscattering response from single pine trees and pine canopies
Helsinki University of Technology,
P.O. Box 3000,
FIN-02015 HUT, Finland,
In this work polarimetric backscattering model has been employed to simulate L-and C-band polarimetric backscattering from single pine tree and pine forest stand. Behaviors of several polarimetric parameters (entropy, alpha angle, covariance matrix elements etc.) are examined as a function of forest and tree geometry parameters (number of branches, stem size, etc.). Also forest interferometric coherence is studied for different polarizations. Lately developed 'Electromagnetic Scattering Model for Forest Remote Sensing', elaborated in Rolf Nevanlinna institute in Finland (L. Zurk et. al. 2002) has been used. The model extends the discrete particle approach to rigorously handle the first order direct scattering, the single and double ground bounce terms, and the first order interaction between the trunk and branches. For the first order interaction between the trunk and branches it is employs computational segmentation and a local plane wave expansion to provide efficient calculation. The model computes fully coherent polarimetric quantities for general bistatic remote sensing of a forested region at microwave frequencies. The model assumes that the trees are made up of cylinders that represent its trunk and branches. Trees for simulations are created with LIGNUM tree growth model. The LIGNUM model is based on extensive studies of tree growth in Finland and it is able to generate photo-realistic trees. Results are discussed and compared with results obtained from SAR images. In comparison EMISAR images from 1995 from Finland are used.