Coherent Radar Backscatter Modeling of Three-Dimensional Forest Canopies
Guoqing
Sun, Department of Geography, University of Maryland, quoqing@ltpmail.gsfc.nasa.gov
(Presenting)
Dawei
Liu, Institute of Remote Sensing Applications, Chinese Academy of Sciences, david_liu863@163.com
A three-dimensional coherent radar backscattering model for forest canopies based on realistic three-dimensional scene is described in this paper. The realistic spatial structure of forest canopies is established through combined use of forest growth model and fractal tree model. A forest growth model parameterized using local environmental parameters provides information of forest stands structure composition in different growth phases. A fractal tree model (L-system) was used to simulate individual 3-D tree structure of different ages or heights. A forest stand is composed of trees with species and sizes simulated from tree growth model. Trees were randomly positioned in a stand resulting in a 3-D medium of discrete scatterers. The radar coherent backscatter model takes the 3-D forest scene as input and simulates the coherent radar backscattering signature. The scattering matrices of all scatterers within a pixel are coherently added to yield the total backscattering field. In this process, the phase information of backscattering is preserved, so the model can be used to simulate interferometric SAR data.
The simulation results of the coherent model were compared with the JERS-1 L-band SAR and ENVISAT ASAR C-band data from pure birch forests of Changqing test site in Daxinganling, Northern China. In sensitivity analysis of this model, the scattering phase center height simulation of birch forest stands shows that interferometric SAR response to forest canopies is influenced by its spatial structure intensively.