Polarization Characteristics Analysis Of Target Surface Based On PBRDF Model

Imaging detection is an important means to obtain target information.The traditional imaging detection technology mainly collects the intensity information and spectral information of the target,and classifies the target by analyzing and processing the image information.In practical application,due to the mixed scenes,the target may be affected by the skylight background and climate interference,so it can not meet the needs of target recognition.Compared with traditional detection techniques,polarization detection can not only analyze polarized images,but also make use of the unique polarization properties of light acting on the target.In this paper,the reflection mechanism of target surface is studied from the microscopic perspective,and the polarization characteristic model is established to represent the relationship between the polarization state of reflected light and the target surface parameters,and the polarization characteristic test experiment is carried out.The experimental data are used to invert the target surface parameters,providing a new information dimension for intelligent target recognition.The main research contents are as follows:Firstly,the scattering characteristics of polarized light are studied based on the microplane element theory,and the scattering from the target surface is divided into specular reflection,diffuse reflection and volume scattering,that is single reflection from the surface,multiple reflection from the surface,and the part of light emitted from the surface after interacting with particles inside the material.A polarization bidirectional reflection distribution function(pBRDF)model for rough surface targets is established based on the three-component assumption,and the expression of polarization degree of target reflected light is derived from the model.Secondly,the polarization measurement system of target surface is designed and built,which consists of active lighting device,polarization measurement device and information processing device.By changing the position of the SALSA polarizing camera,the polarized images of different material objects at different angles are collected under the active illumination of fully linearly polarized light.Then the acquired image information is processed and the polarization characteristics of the target are described by the degree of polarization.The measured data show that the degree of polarization has a great relationship with zenith angle and azimuth angle.The polarization degree of the target is minimum in the direction of incident light source and maximum in the direction of specular reflection.Target classification can be realized by comparing the polarization degree of different materials with their different polarization characteristics.Finally,the complex refractive index of the target is inverted using the experimental data.The high accuracy of inversion results proves the applicability of the model,and the extinction coefficient K can also be used to classify targets effectively.Then the inversion results are substituted into the model to simulate the polarization degree.The simulation results are in good agreement with the measured results,which proves that the pBRDF model established in this paper can provide theoretical support for the analysis of polarization characteristics of target surface.