近水平观测条件下大气背景光偏振度的计算模型

Computational model for polarization degree of airlight under condition of near-horizontal observation

在光电成像领域,偏振滤波抑制大气背景光是提高成像质量的重要技术途径,其前提条件是分析和计算近水平观测条件下大气背景光偏振度。经典的Rayleigh散射理论和Wilkie天空光偏振模型在近水平观测条件下计算大气背景光偏振度存在较大误差。通过改进Wilkie模型,给出以观测地的经纬度、观测日期和时间、观测方向及大气能见度为输入的近水平观测条件下大气背景光偏振度的计算模型。实验表明:该模型在近水平观测条件下取得比Rayleigh散射理论和Wilkie天空光偏振模型更精确的大气背景光偏振度计算结果。此外,分析了偏振片消光比对大气背景光偏振度测量误差的影响。

In the field of electro-optical imaging,polarization filtering is one of the significant technologies to reject airlight to improve imaging quality,with a prerequisite of analyzing and computing the polarization degree of airlight under condition of near-horizontal observation.In this case,utilizing the classical Rayleigh scattering theory and Wilkie skylight polarization model to compute the polarization degree of airlight resulted in larger error.Therefore,by modifying Wilkie skylight polarization model,a computational model for the polarization degree of airlight under condition of near-horizontal observation was developed in this paper.The inputs of this model contained the latitude and longitude of an observation site,date and time of observation,direction of observation and atmospheric visibility.Experiments indicate that this model can provide more accurate results than both the Rayleigh scattering theory and the Wilkie skylight polarization model under condition of near-horizontal observation.Moreover the influence of extinction ratio on measurement error for the polarization degree of airlight was analyzed.