A Discrete Scatterer Technique for Evaluating Electromagnetic Scattering from Trees
Technical Report,01 Jan 2015,21 Sep 2016
Sensors and Electron Devices Directorate, US Army Research Laboratory Adelphi United States
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An analytical solver is developed for characterizing the coherent scattering responses of trees. Realistic 3-D tree structures are first constructed using an open-source random tree generation engine. The trees are then parsed into discrete, canonical scatterers, such as cylinders and disks, and a multi-ray approach is applied for the calculation of the aggregate response of the scene, with the transmissivity of each ray determined from a cell-based representation of the computational domain. As each scatterer in the outlined framework is assigned a deterministic position, the spatial distribution of the trees and their canopy structures is fully preserved. A cell-by-cell strategy is also proposed for speeding up the calculations of the responses from small components such stems and leaves, which are expected to far outnumber those scatterers composing the main trunks. The accuracy of the analytical solver is assessed by comparing simulation results for a forest stand with solutions from a large-scale, full-wave solver. The primary aim of this study is to develop an accurate and computationally efficient solver to facilitate scattering simulations of realistic forest scenes for airborne foliage-penetration radar applications.