A perceptual stopping condition for global illumination computations Nawel Takouachet∗

The aim of realistic image synthesis is to produce high fidelity im-ages that authentically represent real scenes. As these images are produced for human observers, we may exploit the fact that not ev-erything is perceived when viewing scene with our eyes. Thus, it is clear that taking advantage of the limited capacity of the human visual system (HVS), can significantly contribute to optimize ren-dering software. Global illumination methods are used to simulate realistic lighting in 3D scenes. They generally provide a progressive convergence to high-quality solution. One of the problem of such algorithms is to determine a stopping condition, for deciding if calculations reached a satisfactory convergence allowing the process to terminate. In this paper, we propose and we discuss different solutions to this important problem. We show different techniques based on the Vi-sual Difference Predictor (VDP) proposed by Daly [Daly 1993] to define a perceptual stopping condition for rendering computations. We use the VDP to measure the perceived differences between ren-dered images and to guide the Path Tracing rendering to satisfy a perceptual quality. Also, in a controlled experimental setting with real subjects, we validate our results