Based on the three-component assumption that the reflection is divided into specular reflection,directional diffuse reflection,and ideal diffuse reflection,a bidirectional reflectance distribution function（BRDF） mod...Based on the three-component assumption that the reflection is divided into specular reflection,directional diffuse reflection,and ideal diffuse reflection,a bidirectional reflectance distribution function（BRDF） model of metallic materials is presented.Compared with the two-component assumption that the reflection is composed of specular reflection and diffuse reflection,the three-component assumption divides the diffuse reflection into directional diffuse and ideal diffuse reflection.This model effectively resolves the problem that constant diffuse reflection leads to considerable error for metallic materials.Simulation and measurement results validate that this three-component BRDF model can improve the modeling accuracy significantly and describe the reflection properties in the hemisphere space precisely for the metallic materials.展开更多
In this study, the bidirectional reflectance distribution function （BRDF） of a one-dimensional conducting rough surface and a dielectric rough surface are calculated with different frequencies and roughness values i...In this study, the bidirectional reflectance distribution function （BRDF） of a one-dimensional conducting rough surface and a dielectric rough surface are calculated with different frequencies and roughness values in the microwave band by using the method of moments, and the relationship between the bistatic scattering coefficient and the BRDF of a rough surface is expressed. From the theory of the parameters of the rough surface BRDF, the parameters of the BRDF are obtained using a genetic algorithm. The BRDF of a rough surface is calculated using the obtained parameter values. Further, the fitting values and theoretical calculations of the BRDF are compared, and the optimization results are in agreement with the theoretical calculation results. Finally, a reference for BRDF modeling of a Gaussian rough surface in the microwave band is provided by the proposed method.展开更多
We present a bidirectional reflection distribution function （BRDF） model for thermal coating surfaces based on a three-component reflection assumption, in which the specular reflection is given according to the micr...We present a bidirectional reflection distribution function （BRDF） model for thermal coating surfaces based on a three-component reflection assumption, in which the specular reflection is given according to the microfacet theory and Snell＇s law, the multiple reflection is considered Nth cosine distributed, and the volume scattering is uniformly distributed in reflection angles according to the experimental results. This model describes the reflection characteristics of thermal coating surfaces more completely and reasonably. Simulation and measurement results of two thermal coating samples SR107 and S781 are given to validate that this three-component model significantly improves the modeling accuracy for thermal coating surfaces compared with the existing BRDF models.展开更多
An expression of degree of polarization（DOP） for metallic material is presented based on the three-component polarized bidirectional reflectance distribution function（p BRDF） model with considering specular reflec...An expression of degree of polarization（DOP） for metallic material is presented based on the three-component polarized bidirectional reflectance distribution function（p BRDF） model with considering specular reflection, directional diffuse reflection and ideal diffuse reflection. The three-component p BRDF model with a detailed reflection assumption is validated by comparing simulations with measurements. The DOP expression presented in this paper is related to surface roughness, which makes it more reasonable in physics. Test results for two metallic samples show that the DOP based on the three-component p BRDF model accords well with the measurement and the error of existing DOP expression is significantly reduced by introducing the diffuse reflection. It indicates that our DOP expression describes the polarized reflection properties of metallic surfaces more accurately.展开更多
多尺度非均匀背景为不同尺度和形状且在空间上分布不均匀的粗糙结构。本文针对多尺度非均匀粗糙背景散射特性快速计算问题,提出了基于散射中心方法的参数化表征模型。多尺度非均匀背景的散射场一般由地表大尺度表面所产生的镜反射分量...多尺度非均匀背景为不同尺度和形状且在空间上分布不均匀的粗糙结构。本文针对多尺度非均匀粗糙背景散射特性快速计算问题,提出了基于散射中心方法的参数化表征模型。多尺度非均匀背景的散射场一般由地表大尺度表面所产生的镜反射分量、大尺度表面几何不连续处所产生的绕射分量和地表小尺度粗糙面引起的漫散射分量共同组成。传统雷达目标散射中心建模采用分布型、局部型和滑动型散射中心模型(scattering center model, SCM)表征目标的反射和绕射散射;但是,传统散射中心表征形式仅能描述大尺度光滑表面、几何不连续处的散射场,无法描述小尺度粗糙面的散射效应。本文结合粗糙面的相干-非相干散射理论,在大尺度地形散射中心表征模型的基础上,利用相干模型修正小尺度粗糙面对大尺度表面散射场幅度的影响;利用双向反射分布函数(bidirectional reflectance distribution function, BRDF)建立非相干散射的参数化表征形式。对两种非均匀多尺度背景的散射特性进行参数化表征,并采用商业软件高频求解器对计算结果的精度和效率进行了校验,证明了粗糙背景散射中心参数化建模方法的可行性。展开更多
文摘Based on the three-component assumption that the reflection is divided into specular reflection,directional diffuse reflection,and ideal diffuse reflection,a bidirectional reflectance distribution function（BRDF） model of metallic materials is presented.Compared with the two-component assumption that the reflection is composed of specular reflection and diffuse reflection,the three-component assumption divides the diffuse reflection into directional diffuse and ideal diffuse reflection.This model effectively resolves the problem that constant diffuse reflection leads to considerable error for metallic materials.Simulation and measurement results validate that this three-component BRDF model can improve the modeling accuracy significantly and describe the reflection properties in the hemisphere space precisely for the metallic materials.
基金Project supported by the National Natural Science Foundation for Distinguished Young Scholars of China （Grant No. 61225002）, the Aeronautical Science Fund and Aviation Key Laboratory of Science and Technology on Avionics Integrated Sensor System Simulation, China （Grant No. 20132081015）, and the Fundamental Research Funds for the Central Universities, China （Grant No. SPSZ031403）
文摘In this study, the bidirectional reflectance distribution function （BRDF） of a one-dimensional conducting rough surface and a dielectric rough surface are calculated with different frequencies and roughness values in the microwave band by using the method of moments, and the relationship between the bistatic scattering coefficient and the BRDF of a rough surface is expressed. From the theory of the parameters of the rough surface BRDF, the parameters of the BRDF are obtained using a genetic algorithm. The BRDF of a rough surface is calculated using the obtained parameter values. Further, the fitting values and theoretical calculations of the BRDF are compared, and the optimization results are in agreement with the theoretical calculation results. Finally, a reference for BRDF modeling of a Gaussian rough surface in the microwave band is provided by the proposed method.
文摘We present a bidirectional reflection distribution function （BRDF） model for thermal coating surfaces based on a three-component reflection assumption, in which the specular reflection is given according to the microfacet theory and Snell＇s law, the multiple reflection is considered Nth cosine distributed, and the volume scattering is uniformly distributed in reflection angles according to the experimental results. This model describes the reflection characteristics of thermal coating surfaces more completely and reasonably. Simulation and measurement results of two thermal coating samples SR107 and S781 are given to validate that this three-component model significantly improves the modeling accuracy for thermal coating surfaces compared with the existing BRDF models.
文摘An expression of degree of polarization（DOP） for metallic material is presented based on the three-component polarized bidirectional reflectance distribution function（p BRDF） model with considering specular reflection, directional diffuse reflection and ideal diffuse reflection. The three-component p BRDF model with a detailed reflection assumption is validated by comparing simulations with measurements. The DOP expression presented in this paper is related to surface roughness, which makes it more reasonable in physics. Test results for two metallic samples show that the DOP based on the three-component p BRDF model accords well with the measurement and the error of existing DOP expression is significantly reduced by introducing the diffuse reflection. It indicates that our DOP expression describes the polarized reflection properties of metallic surfaces more accurately.
文摘多尺度非均匀背景为不同尺度和形状且在空间上分布不均匀的粗糙结构。本文针对多尺度非均匀粗糙背景散射特性快速计算问题,提出了基于散射中心方法的参数化表征模型。多尺度非均匀背景的散射场一般由地表大尺度表面所产生的镜反射分量、大尺度表面几何不连续处所产生的绕射分量和地表小尺度粗糙面引起的漫散射分量共同组成。传统雷达目标散射中心建模采用分布型、局部型和滑动型散射中心模型(scattering center model, SCM)表征目标的反射和绕射散射;但是,传统散射中心表征形式仅能描述大尺度光滑表面、几何不连续处的散射场,无法描述小尺度粗糙面的散射效应。本文结合粗糙面的相干-非相干散射理论,在大尺度地形散射中心表征模型的基础上,利用相干模型修正小尺度粗糙面对大尺度表面散射场幅度的影响;利用双向反射分布函数(bidirectional reflectance distribution function, BRDF)建立非相干散射的参数化表征形式。对两种非均匀多尺度背景的散射特性进行参数化表征,并采用商业软件高频求解器对计算结果的精度和效率进行了校验,证明了粗糙背景散射中心参数化建模方法的可行性。
