计算机工程Issue(3)：228-236,9.DOI:10.3969/j.issn.1000-3428.2015.03.043
针对薄层介质的多极漫射模型扩展
Extension of Multipole Diffusion Model for Thin Medium
摘要
Abstract
The Multipole diffusion model is a simple model that well describes light scattering in translucent materials. However,it is not well suited for very thin medium, particularly those close to or thinner than one Mean Free Path ( MFP) . This paper tries to extend the Multipole diffusion model for very thin medium with reasonable accuracy. It reviews the Multipole diffusion model and its assumptions,and to relax one of the assumptions by separating the direct transmitting component and the diffuse component of light. It adjusts the way the Multipole model places its point light sources to better match characteristics of light transport in thin medium. The diffuse part of the light is calculated using the modified source placement, and the direct transmitting part is approximated using a Dirac delta distribution. To evaluate the accuracy of the extended model,it is compared with the classical Multipole and Monte-Carlo simulations. The resulting profiles is predicted by the three models,as well as actual renderings. It is shown that the classical Multipole model is unable to compute profiles correctly for materials close to or less than one MFP thick. The extended model matches Monte-Carlo results better than the classical Multipole model. The extension of the current Multipole diffusion model proposed is suitable for medium close to or thinner than one MFP, and matches the Monte-Carlo method with reasonable accuracy. It can be easily integrated with existing Multipole implementations.关键词
次表面散射/半透明/薄层介质/漫射模型/反射分布/平均自由程Key words
subsurface scattering/translucent/thin materials/diffusion model/reflectance profile/Mean Free Path( MFP)分类
信息技术与安全科学引用本文复制引用
吴一帆,杨旭波..针对薄层介质的多极漫射模型扩展[J].计算机工程,2015,(3):228-236,9.基金项目
国家自然科学基金资助项目(61373085,61173105,60970051)。 （61373085,61173105,60970051）
