Research On The Modeling And Influencing Factors Of Polarization Characteristics Of Typical Targets In Near Infrared

Polarization is one of the essential characteristics of light.For any object,light reflected from surfaces is partly polarized.The polarization characteristic,closely related to the own natures of the target,is the most inherent property of the target.The polarized properties of targets with different natures are quite different.Especially,the polarized properties between the target and background are more obvious.The modeling of polarization characteristics,as a theoretical basis for the effective identification of the target in the natural environment,is the premise of studying the difference of polarized reflectance properties of different targets.The analysis of polarization characteristics is one of the hotpots for the research of targets characteristics.The modeling of polarization characteristics of the target and background in near-infrared band is a useful complement to the modeling in visible band.However,most of the existing polarized bidirectional reflectance distribution function(pBRDF)models are aimed at visible band,and the pBRDF models in near-infrared band has not been further studied.In the near-infrared wavelength range,the modeling methods of the polarization characteristics of the painted surfaces and natural ground-feature’s background have been studied in this thesis.The main works include:Under different observation geometries in the field,the spectral properties and hemispherical distribution characteristics of polarization information for typical painted surfaces and natural ground-feature’s background have been studied.To obtain the polarized reflectance information of the target,an automatic polarization detection system is built based on the theory of multi-angular polarization detection.The system comprise:goniometer,automatic polarimetric spectrometer,mainly control software and target samples.At the same time,the automatic polarimetric spectrometer has been implemented polarized calibration experiment.The modeling method of scattering polarization properties of painted surfaces is studied.A multiple-component polarized BRDF model is established on the basis of the Kubelka-Munk(KM)theory with the considering of surface scattering and volume scattering.The model introduces the mirror parameter to characterize surface scattering contributions,and makes the new polarized BRDF model containing five parameters more consistent with the actual scattering polarization of painted surfaces.The degree of polarization data sets for green,black and yellow painted surfaces have been used to invert the five key parameters and verified the accuracy of the model.The results show that the simulated results based on the multiple-component polarized BRDF model coincide with the experimental data for different painted surfaces,and the accuracy is improved by the introduction of mirror parameter.The modeling method of polarized reflectance properties of natural ground-feature’s background is studied.Based on the multi-component polarized BRDF model with the basis of the Kubelka-Munk theory,a backscattering component of Gaussian distribution is introduced,and a six-component polarized BRDF model is presented.The model is more consistent with the polarized reflectance properties of natural ground-feature’s background.Using the measured polarized reflectance factors of grass and soil under different observation geometries at 865nm,and combing the genetic algorithms,six parameters in the model have been fitted.The simulated polarization values from the six-component model are compared with the measured data.It is show that a good agreement is obtained between polarization measurement data and modeled results.The accuracy and validity of model are confirmed.The elimination method of diffuse skylight from the polarized BRDF measurement of painted surfaces under high-loading aerosol conditions is studied.A new diffuse skylight elimination method is proposed by coupling the multi-component polarized BRDF model based on the Kubelka-Munk theory and RT3 model.The new method has been quantitatively compared and verified with the traditional shadow masked method by combing the measured degree of polarization for green and yellow painted surfaces.The results show that the calculated values of degree of polarization for painted surfaces by this method are closer to the theoretical values,which improves the accuracy of measurement.A new approach is provided to measure the polarization information for the ground target under the special weather conditions in the field.