title: Spherical piecewise constant basis functions for all-frequency precomputed radiance transfer.
abstract: This paper presents a novel basis function, called spherical piecewise constant basis function (SPCBF), for precomputed radiance transfer. SPCBFs have several desirable properties: rotatability, ability to represent all-frequency signals, and support for efficient multiple product. By smartly partitioning the illumination sphere into a set of subregions, and associating each subregion with an SPCBF valued 1 inside the region and 0 elsewhere, we precompute the light coefficients using the resulting SPCBFs. Efficient rotation of the light representation in SPCBFs is achieved by rotating the domain of SPCBFs. We run-time approximate the BRDF and visibility coefficients using the set of SPCBFs for light, possibly rotated, through fast lookup of summed-area-table (SAT) and visibility distance table (VDT), respectively. SPCBFs enable new effects such as object rotation in all-frequency rendering of dynamic scenes and on-the-fly BRDF editing under rotating environment lighting. With graphics hardware acceleration, our method achieves real-time frame rates.
authors.affiliation: Department of Computer Science and Technology, Tsinghua University, Beijing, People's Republic of China. xu-k@mails.tsinghua.ed.cn
authors.forename: Kun
authors.initials: K
authors.lastname: Xu
authors.forename: Yun-Tao
authors.initials: YT
authors.lastname: Jia
authors.forename: Hongbo
authors.initials: H
authors.lastname: Fu
authors.forename: Shimin
authors.initials: S
authors.lastname: Hu
authors.forename: Chiew-Lan
authors.initials: CL
authors.lastname: Tai