Analysis Of Scattering Characteristics Of Ground Objects And Imaging Simulation Based On Vector Radiation Transfer Equatio

The study on electromagnetic scattering characteristics of ground objects has been of great application value in remote sensing,detection,anti-stealth and other fields.The types of ground objects and the distribution of differences with environmental changes also show diversity.With the expansion of computing scenarios,the construction of theoretical models becomes more complex,and the amount of computation will increase significantly.As a result,existing computing platforms and modeling capabilities are inadequate.The electromagnetic scattering characteristics of typical ground objects in large scene environment cannot be simulated and obtained accurately.It should be noticed that theoretical models differ greatly from experimental measurements.Therefore,an efficient analytical modeling analysis method needs to be established.The electromagnetic scattering characteristics of typical ground objects can be analyzed accurately and efficiently.It can be used as an efficient tool for the simulation of electromagnetic characteristics of actual large ground scene.In the first part of this thesis,a method based on Vector Radiative Transfer(VRT)equation is proposed to study vegetation scattering characteristics in ground object environment.At the same time,the applicability of various solutions in the transport equation is analyzed.Finally,the iterative method is selected to solve the scattering coefficient of vegetation modeling on rough surface.Based on VRT modeling theory,the higher order iterative solution of VRT equation for particle layer on rough surface is derived.The secondary scattering term between particles and the multiple scattering term between particles and rough surface are analyzed.In this thesis,the Mueller matrix solution of VRT equation of multi-layer vegetation model is derived.The solution considering that the canopy is a mixed particle state,and the transmission mechanism of electromagnetic wave in canopy+trunk+surface environment is studied.Finally,the scattering coupling between different levels and the scattering effect between different levels are simulated and analyzed,which can simulate and calculate the electromagnetic scattering characteristics of vegetation units in typical ground object environment.In the second part of this thesis,the scattering characteristics of three-dimensional vegetation environment are studied by using the transmission theory and 3D modeling.At first,the ground object elements were voxelized by fast grid generation of octree voxels.Secondly,the ray-tracing method is used to study the grid paths of electromagnetic waves in the modeling environment.Then,the three-dimensional VRT method is used to analyze the variation of electromagnetic ray energy and calculate the scattered energy distribution in vegetation area.In order to simulate the Synthetic-Aperture Radar(SAR)imaging process of ground features and vegetation,an imaging simulation algorithm is proposed.Mapping and Projection Algorithm(MPA)is used to this Algorithm,and considers the equivalent path of electromagnetic wave propagation.Then,the vegetation environment simulation can be obtained by 3 steps,namely is modeling and subdivision、three-dimensional vector radiative transfer equation solution and mapping projection algorithm.And the imaging characteristics of random vegetation model in three-dimensional space can be analyzed.In this thesis,the scattering theory model of ground object environment vegetation modeling is proposed,and the scattering characteristics of ground object environment are analyzed by the analytic method.The correctness of the theoretical model and analytical method is verified by simulation examples.