Applications of irradiance tensors to the simulation of non-Lambertian phenomena
Applications of irradiance tensors to the simulation of non-Lambertian phenomena
复制标题
辐照度张量在非朗伯现象模拟中的应用
DOI：
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发表时间：
1995
期刊：
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通讯作者：
James Arvo
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文献类型：
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作者：
James Arvo
我们提出了计算非漫射灯具照度和非漫射表面散射的新技术。这些方法是基于使用称为辐照度张量的辐照度的推广而得到的新的闭合形式的表达式。这些张量的元素是角矩，辐射场的加权积分，在模拟各种非漫射现象时很有用。应用包括计算由于方向变化的面光源、来自光滑表面的反射以及通过光滑表面的传输而产生的辐照度。这些原理适用于单位球面上用多项式表示的任何发射、反射或透射率分布。我们推导了这些函数的一个简单但通用的子类的表达式，称为轴矩，并给出了完整的算法，它们在多面体环境中的精确计算。通过模拟类Phong辐射和散射效应对算法进行了验证。Cr
We present new techniques for computing illumination from non-diffuse luminaires and scattering from non-diffuse surfaces. The methods are based on new closed-form expressions derived using a generalization of irradiance known as irradiance tensors. The elements of these tensors are angular moments, weighted integrals of the radiation field that are useful in simulating a variety of non-diffuse phenomena. Applications include the computation of irradiance due to directionally-varying area light sources, reflections from glossy surfaces, and transmission through glossy surfaces. The principles apply to any emission, reflection, or transmission distribution expressed as a polynomial over the unit sphere. We derive expressions for a simple but versatile subclass of these functions, called axial moments, and present complete algorithms their exact evaluation in polyhedral environments. The algorithms are demonstrated by simulating Phong-like emission and scattering effects. CR