To identify coatings and analyze the anti-detection capabilities of camouflage patterns, material samples can be prepared using the super-pixel segmentation method. A spectral polarization imaging system is developed,...To identify coatings and analyze the anti-detection capabilities of camouflage patterns, material samples can be prepared using the super-pixel segmentation method. A spectral polarization imaging system is developed, based on the principle of bidirectional reflectance distribution function(BRDF), to obtain spectral reflection intensities of coatings at full spatial angles, and use polarization images to calculate the refractive index by the Fresnel equation. The index is then coupled into TorranceSparrow model to simulate the spectral scattering intensity to mutually verify the experimental results. The spectral scattering characteristics of standard camouflage patterns are then revealed and pinpoint the signature band and the angle of reflecting sensitivity.展开更多
为了更好地表征物体表面辐射偏振特性,以P-G模型为基础,针对物体表面微面元分布情况,建立了一种基于柯西分布的二分量偏振双向反射分布函数(Polarization Bidirectional Reflection Distribution Function,PBRDF)模型。基于红外偏振辐...为了更好地表征物体表面辐射偏振特性,以P-G模型为基础,针对物体表面微面元分布情况,建立了一种基于柯西分布的二分量偏振双向反射分布函数(Polarization Bidirectional Reflection Distribution Function,PBRDF)模型。基于红外偏振辐射传输特性,采用黑体辐射定律推导出红外辐射线偏振度模型,并通过设计红外偏振成像实验对该模型进行检验。将实测数据与数值计算结果进行对比,分析引入柯西分布后的红外线偏振度模型相较于高斯分布对精度的影响。结果表明,采用柯西分布表征的微面元模型在描述物体表面的红外线偏振度时具有更好的适用性。研究结果为双向反射分布函数(Bidirectional Reflection Distribution Function,BRDF)模型精度的进一步优化提供了理论支撑与技术支持。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
Based on the study of phase angle and wavelength in pBRDF (Polarized bidirectional reflectance distribution function), roujean model was proposed to describe Orient (Polarization phase angle) quantitatively. The Rouje...Based on the study of phase angle and wavelength in pBRDF (Polarized bidirectional reflectance distribution function), roujean model was proposed to describe Orient (Polarization phase angle) quantitatively. The Roujean model was used to quantitatively describe different fruits intensity components (<i><span style="font-family:Verdana;font-size:12px;">F</span></i><sub><span style="font-family:Verdana;font-size:12px;vertical-align:sub;">00</span></sub><span style="font-family:Verdana;font-size:12px;">) and polarization phase angle (Orient), and the simulation results were analyzed and compared using statistical analysis and comparison methods to realize the prediction from the regular model to the outdoor fruit tree canopy to the canopy of outdoor fruit tree canopy random distribution. The experimental results showed that: 1) when the phase angle of jujube was 52.19<span style="white-space:nowrap;">°</span>, 66.51<span style="white-space:nowrap;">°</span></span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">and 88.26<span style="white-space:nowrap;">°</span>, the </span><i><span style="font-family:Verdana;font-size:12px;">R</span></i><sup><span style="font-family:Verdana;font-size:12px;vertical-align:super;">2</span></sup><span style="font-family:Verdana;font-size:12px;"> and average errors of </span><i><span style="font-family:Verdana;font-size:12px;">F</span></i><sub><span style="font-family:Verdana;font-size:12px;vertical-align:sub;">00</span></sub><span style="font-family:Verdana;font-size:12px;"> parameters described by Roujean model are 0.9982, 0.9963, 0.9912 and 3.80%, 4.17%, 6.40%, respectively;</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">a</span><span style="font-family:Verdana;font-size:12px;">nd the </span><i><span style="font-family:Verdana;font-size:12px;">R</span></i><sup><span style="font-family:Verdana;font-size:12px;vertical-align:super;">2</span></sup><span style="font-family:Verdana;font-size:12px;"> and average error of Orient parameters described by Roujean model are 0.9056,</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">0.9223,</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">0.9260 and 6.23%,</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">3.32%,</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">8.05%, respectively;It can be seen that roujean model can quantitatively describe the Orient parameter of jujube</span><span style="font-family:Verdana;font-size:12px;">;</span><span style="font-family:Verdana;font-size:12px;">2) When the phase angle of apricot was 70.99<span style="white-space:nowrap;">°</span>, 71.28<span style="white-space:nowrap;">°</span> and 67.91<span style="white-space:nowrap;">°</span>, the </span><i><span style="font-family:Verdana;font-size:12px;">R</span></i><sup><span style="font-family:Verdana;font-size:12px;vertical-align:super;">2</span></sup><span style="font-family:Verdana;font-size:12px;"> and average errors of </span><i><span style="font-family:Verdana;font-size:12px;">F</span></i><sub><span style="font-family:Verdana;font-size:12px;vertical-align:sub;">00</span></sub><span style="font-family:Verdana;font-size:12px;"> parameters described by Roujean model </span><span style="font-family:Verdana;font-size:12px;">is</span><span style="font-family:Verdana;font-size:12px;"> 0.9862, 0.9823, 0.9792 and 3.40%,</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">4.82%,</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">5.19%, respectively;</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">And the R</span><sup><span style="font-family:Verdana;font-size:12px;vertical-align:super;">2</span></sup><span style="font-family:Verdana;font-size:12px;"> and average error of Orient parameters described by Roujean model are 0.9382, 0.8947, 0.8849 and 7.19%, 9.28%, 9.47%, respectively.</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">Roujean model can also quantitatively describe the Orient parameter of white apricot. In summary, the Roujean model can provide a good quantitative description of </span><i><span style="font-family:Verdana;font-size:12px;">f</span></i><sub><span style="font-family:Verdana;font-size:12px;vertical-align:sub;">00</span></sub><span style="font-family:Verdana;font-size:12px;"> and a good quantitative description of Orient, which in turn can predict the pBRDF parameter for more fruits with different incidence and detection directions.</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">It can correct the influence of angle factor in the nondestructive testing of outdoor fruits.</span>展开更多
The ocean surface emissivity model plays a pivotal role in satellite data assimilation and the retrieval of ocean physical parameters.In our previous research,we developed a physical emissivity model featuring a polar...The ocean surface emissivity model plays a pivotal role in satellite data assimilation and the retrieval of ocean physical parameters.In our previous research,we developed a physical emissivity model featuring a polarized Bidirectional Reflectance Distribution Function(pBRDF-E).This model effectively ensures the consistency between surface emission and reflection parameters.However,it suffers from low computational efficiency.In this study,we introduce a fast ocean emissivity model,OceanEM.Leveraging the emissivity data output from the pBRDF-E model,OceanEM is developed by using a multilayer perceptron neural network.It can compute the polarization emissivity vector across a wide range of conditions:incidence angles from 0°to 80°,wind speeds from 2 to 50 m s^(-1),sea surface temperatures from-2°to 30℃,sea surface salinities from 0 to 40 psu,and frequencies from 1.4 to 410 GHz.Alongside the FAST Microwave Emissivity Model(FASTEM6)and SURface Fast Emissivity Model for Ocean(SURFEM-ocean),OceanEM is integrated into the Advanced Radiative Transfer Modeling System(ARMS)as a user-selectable option.To validate the accuracy of OceanEM,we compare it with FASTEM6 and SURFEM-ocean using data from WindSAT,a polarimetric radiometer onboard the Coriolis satellite.The results show that the three models generally yield consistent simulations of WindSAT brightness temperatures.Specifically,for channels at 6.8GHz,10.7 GHz(both horizontal and vertical polarization),and 18.7 GHz(vertical polarization),OceanEM demonstrates higher accuracy than FASTEM6 but lower than SURFEM-ocean.Conversely,for channels of 18.7 GHz(horizontal polarization),23.8 GHz,and 37.0 GHz(both horizontal and vertical polarization),OceanEM outperforms both FASTEM6 and SURFEM-ocean.展开更多
基金supported by the Jilin Province Science and Technology Development Plan Item (No.20240402068GH)。
文摘To identify coatings and analyze the anti-detection capabilities of camouflage patterns, material samples can be prepared using the super-pixel segmentation method. A spectral polarization imaging system is developed, based on the principle of bidirectional reflectance distribution function(BRDF), to obtain spectral reflection intensities of coatings at full spatial angles, and use polarization images to calculate the refractive index by the Fresnel equation. The index is then coupled into TorranceSparrow model to simulate the spectral scattering intensity to mutually verify the experimental results. The spectral scattering characteristics of standard camouflage patterns are then revealed and pinpoint the signature band and the angle of reflecting sensitivity.
文摘为了更好地表征物体表面辐射偏振特性,以P-G模型为基础,针对物体表面微面元分布情况,建立了一种基于柯西分布的二分量偏振双向反射分布函数(Polarization Bidirectional Reflection Distribution Function,PBRDF)模型。基于红外偏振辐射传输特性,采用黑体辐射定律推导出红外辐射线偏振度模型,并通过设计红外偏振成像实验对该模型进行检验。将实测数据与数值计算结果进行对比,分析引入柯西分布后的红外线偏振度模型相较于高斯分布对精度的影响。结果表明,采用柯西分布表征的微面元模型在描述物体表面的红外线偏振度时具有更好的适用性。研究结果为双向反射分布函数(Bidirectional Reflection Distribution Function,BRDF)模型精度的进一步优化提供了理论支撑与技术支持。
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Based on the study of phase angle and wavelength in pBRDF (Polarized bidirectional reflectance distribution function), roujean model was proposed to describe Orient (Polarization phase angle) quantitatively. The Roujean model was used to quantitatively describe different fruits intensity components (<i><span style="font-family:Verdana;font-size:12px;">F</span></i><sub><span style="font-family:Verdana;font-size:12px;vertical-align:sub;">00</span></sub><span style="font-family:Verdana;font-size:12px;">) and polarization phase angle (Orient), and the simulation results were analyzed and compared using statistical analysis and comparison methods to realize the prediction from the regular model to the outdoor fruit tree canopy to the canopy of outdoor fruit tree canopy random distribution. The experimental results showed that: 1) when the phase angle of jujube was 52.19<span style="white-space:nowrap;">°</span>, 66.51<span style="white-space:nowrap;">°</span></span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">and 88.26<span style="white-space:nowrap;">°</span>, the </span><i><span style="font-family:Verdana;font-size:12px;">R</span></i><sup><span style="font-family:Verdana;font-size:12px;vertical-align:super;">2</span></sup><span style="font-family:Verdana;font-size:12px;"> and average errors of </span><i><span style="font-family:Verdana;font-size:12px;">F</span></i><sub><span style="font-family:Verdana;font-size:12px;vertical-align:sub;">00</span></sub><span style="font-family:Verdana;font-size:12px;"> parameters described by Roujean model are 0.9982, 0.9963, 0.9912 and 3.80%, 4.17%, 6.40%, respectively;</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">a</span><span style="font-family:Verdana;font-size:12px;">nd the </span><i><span style="font-family:Verdana;font-size:12px;">R</span></i><sup><span style="font-family:Verdana;font-size:12px;vertical-align:super;">2</span></sup><span style="font-family:Verdana;font-size:12px;"> and average error of Orient parameters described by Roujean model are 0.9056,</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">0.9223,</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">0.9260 and 6.23%,</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">3.32%,</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">8.05%, respectively;It can be seen that roujean model can quantitatively describe the Orient parameter of jujube</span><span style="font-family:Verdana;font-size:12px;">;</span><span style="font-family:Verdana;font-size:12px;">2) When the phase angle of apricot was 70.99<span style="white-space:nowrap;">°</span>, 71.28<span style="white-space:nowrap;">°</span> and 67.91<span style="white-space:nowrap;">°</span>, the </span><i><span style="font-family:Verdana;font-size:12px;">R</span></i><sup><span style="font-family:Verdana;font-size:12px;vertical-align:super;">2</span></sup><span style="font-family:Verdana;font-size:12px;"> and average errors of </span><i><span style="font-family:Verdana;font-size:12px;">F</span></i><sub><span style="font-family:Verdana;font-size:12px;vertical-align:sub;">00</span></sub><span style="font-family:Verdana;font-size:12px;"> parameters described by Roujean model </span><span style="font-family:Verdana;font-size:12px;">is</span><span style="font-family:Verdana;font-size:12px;"> 0.9862, 0.9823, 0.9792 and 3.40%,</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">4.82%,</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">5.19%, respectively;</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">And the R</span><sup><span style="font-family:Verdana;font-size:12px;vertical-align:super;">2</span></sup><span style="font-family:Verdana;font-size:12px;"> and average error of Orient parameters described by Roujean model are 0.9382, 0.8947, 0.8849 and 7.19%, 9.28%, 9.47%, respectively.</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">Roujean model can also quantitatively describe the Orient parameter of white apricot. In summary, the Roujean model can provide a good quantitative description of </span><i><span style="font-family:Verdana;font-size:12px;">f</span></i><sub><span style="font-family:Verdana;font-size:12px;vertical-align:sub;">00</span></sub><span style="font-family:Verdana;font-size:12px;"> and a good quantitative description of Orient, which in turn can predict the pBRDF parameter for more fruits with different incidence and detection directions.</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">It can correct the influence of angle factor in the nondestructive testing of outdoor fruits.</span>
基金Supported by the National Key Research and Development Program of China(2021YFB3900400)National Natural Science Foundation of China(U2142212)。
文摘The ocean surface emissivity model plays a pivotal role in satellite data assimilation and the retrieval of ocean physical parameters.In our previous research,we developed a physical emissivity model featuring a polarized Bidirectional Reflectance Distribution Function(pBRDF-E).This model effectively ensures the consistency between surface emission and reflection parameters.However,it suffers from low computational efficiency.In this study,we introduce a fast ocean emissivity model,OceanEM.Leveraging the emissivity data output from the pBRDF-E model,OceanEM is developed by using a multilayer perceptron neural network.It can compute the polarization emissivity vector across a wide range of conditions:incidence angles from 0°to 80°,wind speeds from 2 to 50 m s^(-1),sea surface temperatures from-2°to 30℃,sea surface salinities from 0 to 40 psu,and frequencies from 1.4 to 410 GHz.Alongside the FAST Microwave Emissivity Model(FASTEM6)and SURface Fast Emissivity Model for Ocean(SURFEM-ocean),OceanEM is integrated into the Advanced Radiative Transfer Modeling System(ARMS)as a user-selectable option.To validate the accuracy of OceanEM,we compare it with FASTEM6 and SURFEM-ocean using data from WindSAT,a polarimetric radiometer onboard the Coriolis satellite.The results show that the three models generally yield consistent simulations of WindSAT brightness temperatures.Specifically,for channels at 6.8GHz,10.7 GHz(both horizontal and vertical polarization),and 18.7 GHz(vertical polarization),OceanEM demonstrates higher accuracy than FASTEM6 but lower than SURFEM-ocean.Conversely,for channels of 18.7 GHz(horizontal polarization),23.8 GHz,and 37.0 GHz(both horizontal and vertical polarization),OceanEM outperforms both FASTEM6 and SURFEM-ocean.
