Animating radiosity environments through the Multi‐Frame Lighting Method

Abstract

Realistic rendering animation is known to be an expensive processing task when physically based global illumination methods are used in order to improve illumination details. This paper presents the Multi-Frame Lighting Method, an efficient algorithm to compute animations in radiosity environments. The method, based on global Monte Carlo techniques, performs the lighting simulation of groups of consecutive frames in a single process. All frames computed have the same accuracy as if they were computed independently while a significant high speed-up is achieved. Results show that the method it is an interesting alternative for computing non-interactive radiosity animations for moderately complex scenarios. Copyright IntroductionHigh-quality realistic animation is often a desired objective in image synthesis. The accurate computation of the illumination plays a very important role in the improvement of realism on simulated sequences. For this reason, global illumination models are required when computing realistic animations. These models have in general a high computational cost when dealing with complex scenarios where we want to simulate illumination details like soft shadows, diffuse interreflections or more complex lighting phenomena involving caustics or participating media. For animations, usually composed of sequences of lots of images, this problem grows, leading to large amounts of computation if each frame is treated independently. Thus, efficient solutions are searched in order to reduce the computation cost. Considering that in most cases changes in illumination between consecutive frames are usually smooth as a consequence that animation changes are also smooth, a natural possibility for an efficient approach is to improve global illumination models in order to make use of this source of coherence. For example, a significant computation time can be saved by reusing illumination already computed that is invariant in an interval of time within the animation.The radiosity method, introduced in Goral et al., 1 allows interactive walkthroughs since it is a viewindependent global illumination solution. For this reason, it is an attractive method to be used both in animations and in interactive applications. Many works with a focus on this last domain have been proposed. Strategies like progressive refinements methods 2-4 or hierarchical radiosity [5][6][7] have been developed with the goal of quickly updating changes in illumination for a given demand. In the case of non-interactive radiosity animations, [8][9][10][11][12] where all time-dependent parameters can be known a priori, requirements are not the same as in the interactive case: there is not a high compromise on speeding updates of single frames. However, a large number of frames must be computed, maintaining a high-quality level of accuracy. Although in most cases interactive techniques could be adapted to animation purposes, a specific approach for animations can extract more benefits.In this paper we present the Multi-Frame Lighting Method, a M...

Temporal Radiance Caching

“…Many approaches for such computation have been proposed in the last 20 years. Most of these methods are based on radiosity, such as those in [1], [2], [3], and [4]. However, radiosity methods are prone to visual artifacts due to undersampling or high memory consumption and computational cost due to high-quality sampling.…”