目标表面遮蔽函数参数的反演与BRDF统计建模的优化  

Inversion parameters of shadowing function and optimization of BRDF statistical modeling on target surface

作　　者：黄朝军[1] 刘亚锋[1] 尹继武[1] 孙彦清[1] 龙姝明[1] 

机构地区：[1]陕西理工学院物理系,陕西汉中723001

出　　处：《红外与激光工程》2010年第5期883-886,891,共5页Infrared and Laser Engineering

基　　金：陕西省自然科学基金资助项目(2009JM10122010JM5011);陕西省教育厅专项科研计划资助项目(09JK376)

摘　　要：遮蔽函数是目标表面双向反射分布函数(BRDF)统计建模中的一个重要因子,工程应用中常将遮蔽函数中的参数取一组不变的经验值,这种近似具有一定优越性,适合一般工程应用。但对于不同材料,这种做法缺乏理论依据,不能准确反映材料表面的散射特性,会给计算结果带来较大误差。利用目标表面CCD图像灰度图,结合图像处理,计算了像素的灰度梯度。通过遗传模拟退火算法反演出BRDF中遮蔽函数的参数,用反演得到的参数替换遮蔽函数中的经验参数计算水泥板表面的BRDF,并将拟合值和BRDF的实验值相比较,结果表明:随入射角增大,遮蔽函数参数取反演值时的BRDF比取经验值时的BRDF精度更高,为目标表面BRDF统计建模的优化提供了一种方法。The shadowing function is an important factor of BRDF statistical modeling on target surface.The parameters of shadowing function is commonly substituted by a set of fixed empirical value in general engineering application.This approximation with definite superiority lacks theory basis for different material,which can not only accurate inversion scattering property of material surface,but also results in major error of calculation result.Using CCD image grey-scale map and combined with image processing,the gray gradient of image element was calculated.After inversing the parameters of shadowing function through genetic simulated annealing algorithm,the BRDF of the cement board surface was computed by replacing the experimental parameters of shadowing function with inversion parameters,and the computed fitted value was compared with experimental value of BRDF.The results show that the precision of BRDF is higher with the increasing of the incident angle,when the parameters of shadowing function gets inversion value.It provides an efficient approach for the optimization of BRDF model on target surface.

关 键 词：遮蔽函数 BRDF 灰度梯度 反演 

分 类 号：O432[机械工程—光学工程]