McGunnigle G, Dong Junyu, Wang Xuefang
CTR AG, Europastrasse 4/1, A-9524 Villach, Austria.
J Opt Soc Am A Opt Image Sci Vis. 2012 Apr 1;29(4):627-36. doi: 10.1364/JOSAA.29.000627.
This paper investigates the use of photometric stereo (PS) with reflectance functions that are diffuse but not Lambertian. We show that, for the special case where light sources are arranged at 90° intervals around the optical axis, standard PS is not limited to Lambertian surfaces, and we define criteria for its use. A series of rough test surfaces are used as models for surface microstructure-we found that the Oren Nayar (ON) reflectance model accurately predicted the surfaces' reflectance functions. The ON model does not meet our theoretical criteria for using PS, but PS performs well in simulations if the microroughness is moderate (rms slope <0.3). When PS was applied to real surfaces, the estimated and actual slopes were highly correlated, but there were significant errors in the slope estimates for the rougher samples.
本文研究了具有漫反射但非朗伯反射特性的反射函数的光度立体法（PS）的应用。我们表明，对于光源围绕光轴以90°间隔排列的特殊情况，标准PS并不局限于朗伯表面，并且我们定义了其使用标准。一系列粗糙测试表面被用作表面微观结构的模型——我们发现奥伦-纳亚尔（ON）反射模型能准确预测表面的反射函数。ON模型不符合我们使用PS的理论标准，但如果微粗糙度适中（均方根斜率<0.3），PS在模拟中表现良好。当PS应用于真实表面时，估计斜率与实际斜率高度相关，但对于较粗糙的样本，斜率估计存在显著误差。
