Interactive Depth of Field Using Simulated Difiusion on a GPU
msra(2006)
摘要
Figure 1: Top: Pinhole camera image from an upcoming feature film. Bottom: Sample results of our depth-of-field algorithm based on simulated diffusion. We generate these results from a single color and depth value per pixel, and the above images render at 23-25 frames per second. The method is designed to produce film-preview quality at interactive rates on a GPU. Fast preview should allow greater artistic control of depth-of-field effects. Abstract Accurate computation of depth-of-field effects in computer graph- ics rendering is generally very time consuming, creating a problem- atic workflow for film authoring. The computation is particularly challenging because it depends on large-scale spatially-varying fil- tering that must accurately respect complex boundaries. A variety of real-time algorithms have been proposed for games, but the com- promises required to achieve the necessary frame rates have made them them unsuitable for film. 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 computation cre- ates depth-of-field blurs by simulating the heat equation for a non- uniform medium. Our alternating direction implicit solution gives rise to separable spatially varying recursive filters that can com- pute large-kernel convolutions in constant time per pixel while re- specting the boundaries between in-focus and out-of-focus objects. Recursive filters have traditionally been viewed as problematic for GPUs, but using the well-established method of cyclic reduction of tridiagonal systems, we are able to vectorize the computation and achieve interactive frame rates.
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关键词
diffusion,depth of field,tridiagonal matrices,alternating- direction implicit methods,heat equation,cyclic re- duction.,gpu
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