基于双向反射分布函数模型的红外偏振仿真

Infrared Polarimetric Scene Simulation Based on Bidirectional Reflectance Distribution Function Model

将含有双参数的柯西分布替代常规高斯分布引入微面元双向反射分布函数(BRDF)模型,同时考虑了目标自身辐射强度的方向依赖性,在此基础上推导了长波红外偏振的数学模型,并在合理范围内对模型做简化与修正使之适用于仿真研究。对数学模型双参数(σ和q)的选择进行理论分析并验证了该模型的灵活性以及优势所在。整个仿真过程使用C语言编程实现,仿真流程主要包括目标及场景建模、模型文件处理及导入、仿真参数设定、偏振模型选择、热辐射计算、Gouraud算法表面绘制。偏振场景仿真结果较为理想,得到的目标红外偏振特性与实际图像基本吻合,表明采用的模型及算法适用于红外偏振的研究,对分析复杂目标长波红外偏振物理特性具有重要的理论意义。

The microfacet bidirectional reflectance distribution function （BRDF） model with the two-parameter Cauchy probability distribution,which substitutes for the model with general Gaussian distribution,is used. The directional dependence of emissivity of the object is also taken into account. On the basis,the deduction of mathematical model of long-wave infrared （LWIR） polarization is described. Reasonable simplification and correction for the model is made in order to make the model to be suitable for simulation. Then this paper analyses how to choose the two parameters （σ and q） of the mathematical model and gives the flexibility validation and advantages of the model. The whole process of simulation is done by using C language,the flow of which includes modeling,processing and importing the file into the system of simulation,setting the parameters of polarimetric model,computing the radiation transfer and rendering surface using Gouraud algorithm. The result of polarimetric scene simulation is desirable,which is basically in conformity with real imagers. It proves that the mathematical model and the algorithm in this paper are adequate for the research of LWIR polarization. The conclusion of this paper is significant basis for studying the LWIR polarimetric characteristic of complex objects.