A Monte Carlo coherent scattering model for forest canopies using fractal-generated trees
A Monte Carlo coherent scattering model for forest canopies using fractal-generated trees
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DOI：
10.1109/36.739083
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发表时间：
1999-12
期刊：
影响因子：
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通讯作者：
Yi-Cheng Lin;K. Sarabandi
中科院分区：
文献类型：
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作者：
Yi-Cheng Lin;K. Sarabandi
开发并验证了基于分形生成树木散射的蒙特卡罗模拟的树冠相干散射模型。与非相干模型相比，本模型计算由真实树木结构组成的森林冠层的相干反向散射，其中保留了各个散射体的相对相位信息。通过采用分形概念和 Lindenmayer 系统以及结合现场测量数据，计算机生成忠实于真实林分的树结构。通过将树结构视为任意倾斜平面（地面）上方的由圆柱体（树干和树枝）和圆盘（叶子）组成的散射体簇来处理电磁散射问题。使用单散射近似，通过平均场照射的每个散射体的各个散射的相干相加获得总散射场。调用 Foldy 近似来计算被建模为多层非均匀介质的森林冠层内的平均场。反向散射统计数据是通过对大量实现进行蒙特卡罗模拟获得的。使用多频多极化合成孔径雷达（SAR）[航天飞机成像雷达-C（SIR-C）]从枫树支架上以多个入射角获取的测量数据验证了模型的准确性。灵敏度分析表明，地面倾斜角和树结构可能会显着影响极化雷达响应，特别是在较低频率下。
A coherent scattering model for tree canopies based on a Monte Carlo simulation of scattering from fractal-generated trees is developed and verified. In contrast to incoherent models, the present model calculates the coherent backscatter from forest canopies composed of realistic tree structures, where the relative phase information from individual scatterers is preserved. Computer generation of tree architectures faithful to the real stand is achieved by employing fractal concepts and Lindenmayer systems as well as incorporating the in situ measured data. The electromagnetic scattering problem is treated by considering the tree structure as a cluster of scatterers composed of cylinders (trunks and branches) and disks (leaves) above an arbitrary tilted plane (ground). Using the single scattering approximation, the total scattered field is obtained from the coherent addition of the individual scattering from each scatterer illuminated by a mean field. Foldy's approximation is invoked to calculate the mean field within the forest canopy that is modeled as a multilayer inhomogeneous medium. Backscatter statistics are acquired via a Monte Carlo simulation over a large number of realizations. The accuracy of the model is verified using the measured data acquired by a multifrequency and multipolarization synthetic aperture radar (SAR) [Spaceshuttle Imaging Radar-C (SIR-C)] from a maple stand at many incidence angles. A sensitivity analysis shows that the ground tilt angle and the tree structure may significantly affect the polarimetric radar response, especially at lower frequencies.