The reflection of ocean surface is often assumed azimuthally symmetric in the previous vector discrete ordinate radiative transfer(VDISORT)and many other radiative transfer solvers.This assumption can lead to obvious ...The reflection of ocean surface is often assumed azimuthally symmetric in the previous vector discrete ordinate radiative transfer(VDISORT)and many other radiative transfer solvers.This assumption can lead to obvious errors in the simulated radiances.In this study,the vector radiative transfer equation is solved with a polarized bidirectional reflection distribution function(pBRDF)for computing the surface-leaving radiation from the lower boundary.An azimuthally asymmetric pBRDF model at visible and infrared bands over oceans is fully coupled with the updated VDISORT model.The radiance at the ocean surface is combined with the contributions of atmospheric scattering and surface properties.It is shown that the radiance at the ocean surface also exhibits a strong angular dependence in the Stokes vector and the magnitudes of I.Q.and V increase for a larger azimuthal dependence of pBRDF.In addition,the solar position affects the peaks of sun glitter pattern,thus modulating the signal magnitudes and the angular distributions.As ocean wind increases,the reflection weakens with reduced magnitudes of Stokes parameters and lessvarying angular distributions.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
This paper retrieves the bidirectional polarization distribution functions (BPDFs) of the distinct urban cover in the Pearl River Delta (PRD) region employing the high spatial resolution of multi-angle polarized measu...This paper retrieves the bidirectional polarization distribution functions (BPDFs) of the distinct urban cover in the Pearl River Delta (PRD) region employing the high spatial resolution of multi-angle polarized measurements made by the Directional Polarimetric Camera (DPC).The BPDF operational products of MICROPOL and POLDER measurements were used to validate the BPDF products of the DPC,with the results demonstrating that the BPDF product of the DPC measurements accurately expresses the surface polarized reflectance.The polarized reflectance of distinct surface types in the PRD region was studied using the DPC measurements.The results demonstrate that the polarized reflectances of different surface types differ and decrease as the normalized difference vegetation index increases.The polarized reflectance of a distinct surface type in the PRD region decreases with increasing scattering angle.The basic theory of investigating surface properties using multi-angle polarized measurements is proposed.展开更多
目标双向反射分布函数BRDF (Bidirectional Reflectance Distribution Function)不仅是陆面遥感的关键地球物理参数,也是星载光学遥感仪器基于地面目标的场地辐射校正重要参量,是影响定标精度的关键要素。传统野外地物多角度测量使用的...目标双向反射分布函数BRDF (Bidirectional Reflectance Distribution Function)不仅是陆面遥感的关键地球物理参数,也是星载光学遥感仪器基于地面目标的场地辐射校正重要参量,是影响定标精度的关键要素。传统野外地物多角度测量使用的观测设备,一般其结构较为复杂,重量体积较大,而且运输和组装过程繁琐,观测目标时容易受地形和交通限制,难以进行高效快速精确的野外测量。近年来,无人机由于其设备操作简便、运输和观测方式灵活等方面的优点,可作为新的观测平台应用于当前遥感试验中。本文设计了一种基于无人机平台的地表BRDF测量装置、观测方案和数据处理流程。利用多旋翼低空无人机和云台的组合,搭载野外地物光谱仪和跟拍相机,通过对地面目标多角度观测和高精度定位及角度控制,实现针对固定目标的多方位角和天顶角观测。本文采用上述设计方案和观测流程,在敦煌辐射校正场开展多次稳定均匀沙漠目标的多角度光谱观测试验,并利用实验观测数据,基于Ross-Li核驱动模型推算了场地BRDF模型参数,并与MODIS的陆表BRDF产品(MCD43C1)及反射率产品(MOD/MYD09)进行对比验证。通过开展野外实验,核验了这种新的BRDF观测手段的可靠性,获取的敦煌地表BRDF参数与MODIS遥感产品有良好的一致性,各波段的相对偏差在5%以内。本研究表明,基于多旋翼无人机的BRDF观测系统,提供了一种全新的地物目标方向反射特性观测方法,可用于自动化高频次场地特性观测以及卫星同步定标等野外实验活动。在保证观测精度的同时,极大地减轻人力物力的投入,值得广泛推广应用。展开更多
基金Supported by the National Natural Science Foundation of China(U2142212 and U2242211),Hunan Provincial Natural Science Foundation of China(2021JC0009)National Key Research and Development Program of China[2019QZKK(Qinghai Tibet KeKao)].
文摘The reflection of ocean surface is often assumed azimuthally symmetric in the previous vector discrete ordinate radiative transfer(VDISORT)and many other radiative transfer solvers.This assumption can lead to obvious errors in the simulated radiances.In this study,the vector radiative transfer equation is solved with a polarized bidirectional reflection distribution function(pBRDF)for computing the surface-leaving radiation from the lower boundary.An azimuthally asymmetric pBRDF model at visible and infrared bands over oceans is fully coupled with the updated VDISORT model.The radiance at the ocean surface is combined with the contributions of atmospheric scattering and surface properties.It is shown that the radiance at the ocean surface also exhibits a strong angular dependence in the Stokes vector and the magnitudes of I.Q.and V increase for a larger azimuthal dependence of pBRDF.In addition,the solar position affects the peaks of sun glitter pattern,thus modulating the signal magnitudes and the angular distributions.As ocean wind increases,the reflection weakens with reduced magnitudes of Stokes parameters and lessvarying angular distributions.
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.
基金supported by the National Basic Research Program of China(Grant No.2010CB950800)the National Natural Science Foundation of China(Grant No.41001207)the Funds of the Chinese Academy of Sciences for Key Topics in Innovation Engineering(Grant No.KZCX2-EW-QN311)
文摘This paper retrieves the bidirectional polarization distribution functions (BPDFs) of the distinct urban cover in the Pearl River Delta (PRD) region employing the high spatial resolution of multi-angle polarized measurements made by the Directional Polarimetric Camera (DPC).The BPDF operational products of MICROPOL and POLDER measurements were used to validate the BPDF products of the DPC,with the results demonstrating that the BPDF product of the DPC measurements accurately expresses the surface polarized reflectance.The polarized reflectance of distinct surface types in the PRD region was studied using the DPC measurements.The results demonstrate that the polarized reflectances of different surface types differ and decrease as the normalized difference vegetation index increases.The polarized reflectance of a distinct surface type in the PRD region decreases with increasing scattering angle.The basic theory of investigating surface properties using multi-angle polarized measurements is proposed.
文摘目标双向反射分布函数BRDF (Bidirectional Reflectance Distribution Function)不仅是陆面遥感的关键地球物理参数,也是星载光学遥感仪器基于地面目标的场地辐射校正重要参量,是影响定标精度的关键要素。传统野外地物多角度测量使用的观测设备,一般其结构较为复杂,重量体积较大,而且运输和组装过程繁琐,观测目标时容易受地形和交通限制,难以进行高效快速精确的野外测量。近年来,无人机由于其设备操作简便、运输和观测方式灵活等方面的优点,可作为新的观测平台应用于当前遥感试验中。本文设计了一种基于无人机平台的地表BRDF测量装置、观测方案和数据处理流程。利用多旋翼低空无人机和云台的组合,搭载野外地物光谱仪和跟拍相机,通过对地面目标多角度观测和高精度定位及角度控制,实现针对固定目标的多方位角和天顶角观测。本文采用上述设计方案和观测流程,在敦煌辐射校正场开展多次稳定均匀沙漠目标的多角度光谱观测试验,并利用实验观测数据,基于Ross-Li核驱动模型推算了场地BRDF模型参数,并与MODIS的陆表BRDF产品(MCD43C1)及反射率产品(MOD/MYD09)进行对比验证。通过开展野外实验,核验了这种新的BRDF观测手段的可靠性,获取的敦煌地表BRDF参数与MODIS遥感产品有良好的一致性,各波段的相对偏差在5%以内。本研究表明,基于多旋翼无人机的BRDF观测系统,提供了一种全新的地物目标方向反射特性观测方法,可用于自动化高频次场地特性观测以及卫星同步定标等野外实验活动。在保证观测精度的同时,极大地减轻人力物力的投入,值得广泛推广应用。
