Michael Kass, Aaron Lefohn, John Owens
Abstract:
Accurate computation of depth-of-field effects in computer graphics
rendering is generally very time consuming, creating a problematic
workflow for film authoring. The computation is particularly
challenging because it depends on large-scale spatially-varying
filtering that must accurately respect complex boundaries. Here we
introduce an approximate depth-of-field computation that is good
enough for film preview, yet can be computed interactively on a GPU.
The method makes use of separable recursive filters to create
efficient large-kernel convolutions. The individual recursive filters
are derived from a minimum principle that produces spatially varying
coefficients in the course of solving a tri-diagonal linear system. A
straightforward GPU implementation of recursive filters would have
poor performance, but using the well-established method of cyclic
reduction, we are able to vectorize the computation and achieve
interactive frame rates.
Paper (PDF)
Additional materials: [movie.avi]
Available as Pixar Technical Memo #06-01