All-frequency shadows using non-linear wavelet lighting approximation
All-frequency shadows using non-linear wavelet lighting approximation
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DOI：
10.1145/1201775.882280
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发表时间：
2003-07
期刊：
影响因子：
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通讯作者：
Ren Ng;R. Ramamoorthi;P. Hanrahan
中科院分区：
文献类型：
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作者：
Ren Ng;R. Ramamoorthi;P. Hanrahan
我们提出了一种基于预先计算光传输的方法，用于在全频率、时变照明下实时渲染物体，并将其表示为高分辨率环境地图。目前的技术局限于小区域的灯光，有明显的阴影，或者大的低频灯光，有非常柔和的阴影。我们的主要贡献是在小波基中近似环境图，只保留最大的项（这被称为非线性近似）。我们通过在同一基上稀疏而精确地编码光传输矩阵来进一步压缩。渲染是通过稀疏光向量乘以稀疏传输矩阵来执行的，这是非常快的。为了精确渲染，使用非线性小波比使用线性球面谐波快一个数量级，线性球面谐波是目前最好的技术。
We present a method, based on pre-computed light transport, for real-time rendering of objects under all-frequency, time-varying illumination represented as a high-resolution environment map. Current techniques are limited to small area lights, with sharp shadows, or large low-frequency lights, with very soft shadows. Our main contribution is to approximate the environment map in a wavelet basis, keeping only the largest terms (this is known as a non-linear approximation). We obtain further compression by encoding the light transport matrix sparsely but accurately in the same basis. Rendering is performed by multiplying a sparse light vector by a sparse transport matrix, which is very fast. For accurate rendering, using non-linear wavelets is an order of magnitude faster than using linear spherical harmonics, the current best technique.