偏振滤波抑制大气背景光的性能计算模型

A New Computational Model for Performance of Airlight Rejection Utilizing Polarization Filtering

如何定量计算和预测在不同条件下偏振滤波抑制大气背景光的效果,目前缺乏合适的性能表征量及其计算模型,为此提出了偏振滤波抑制大气背景光的性能计算模型。定义了大气背景光抑制比(ARR),综合天空光相对光谱辐射功率模型和地面太阳直接辐射光谱模型、地物反射特性等,给出了以太阳方位、相机光轴方向、大气能见度和地物光谱反射率等为输入参数的ARR计算公式。该模型的仿真实验结果表明,在晴天与轻霾天气条件下,太阳夹角、大气能见度和地物类型三因素的变化对ARR的影响依次减弱;太阳夹角的变化强烈影响ARR;偏振滤波对多数地物取得相似的大气背景光抑制效果;ARR指标值越大,图像对比度提高越明显。

There are no appropriate performance characteristic parameters and computational models to quantitatively compute and predict the performance of airlight rejection utilizing polarization filtering under different conditions.Therefore,a computational model for performance of airlight rejection utilizing polarization filtering is presented.This model defines the airlight rejection ratio（ARR）,integrates a model for skylight relative spectral radiant power,a solar spectral model for direct irradiance on horizontal planes,an object reflection characteristic,and other factors,and gives the ARR calculation formula whose inputs contain a sun position,an optical axis direction of a camera,atmospheric visibility,object spectral reflectance,and other parameters.Simulation and experiment of this model indicate that in sunny weather and slight haze weather,the influence respectively resulting from changes of the angular distance between the observation direction and the direction of sunlight,atmospheric visibility,and object types on the ARR gradually weakens;the change of angular distance between the observation direction and the direction of sunlight intensively affects the ARR;polarization filtering achieves similar effect of airlight rejection for most objects;the larger the ARR index is,the more effectively the image contrast is improved.