There-reality : selective rendering in high fidelity virtual environments

There-reality environments are those virtual environments which evoke the same perceptual response from a viewer as if they were actually present, or there, in the real scene being depicted. While it is possible to compute highly accurate representations of real scenes, the computational requirements of such a full physically-based global illumination solution are significant, currently precluding its computation on even a powerful modern PC in reasonable let alone real time. However, to provide a useful tool, there-reality environments need to be interactive. A key factor to consider if we are ever to achieve such “Realism in Real-Time” is that we are computing images for humans to look at. Although the human visual system is very good, it is by no means perfect. By understanding what the human does, or perhaps more importantly, does not see, enables us to save substantial computation effort without any loss of perceptual quality of the resultant image. This paper describes the novel techniques of selective rendering which allow us to direct computational resources to those areas of high perceptual importance while avoiding computing any detail which will not be perceived by the viewer. Such selective rendering methods offer us the real possibility of achieving there-reality environments of complex scenes at interactive rates

The influence of sound effects on the perceived smoothness of rendered animations

The developers and users of interactive computer graphics (CG), such as 3D games and virtual reality, are demanding ever more realistic computer generated imagery delivered at high frame rates, to enable a greater perceptual experience for the user. As more computational power and/or transmission bandwidth are not always available, special techniques are applied that trade off fidelity in order to reduce computational complexity, while trying to minimise the perceptibility of the resulting visual defects. Research on human visual perception has promoted the development of perception driven CG techniques, where knowledge of the human visual system and its weaknesses are exploited when rendering/displaying 3D graphics. It is well known in the human perception community that many factors, including audio stimuli, may influence the amount of cognitive resources available to perform a visual task. In this paper we investigate the influence sound effects have on the perceptibility of motion smoothness in an animation (i.e. on the perception of delivered frame rate). Forty participants viewed pairs of computer-generated walkthrough animations (with the same visual content within the pair) displayed at five different frame rates, in all possible combinations. Both walkthroughs in each test pair were either silent or accompanied by sound effects and the participant had to detect the one that had a smoother motion (i.e. was delivered at higher frame rate). A significant effect of sound effects on the perceived smoothness was revealed. The participants who watched the audiovisual walkthroughs gave more erroneous answers while performing their task compared to the subjects in the "No Sound" group, regardless of their familiarity with animated CG. Especially the unfamiliar participants failed to notice motion smoothness variations which were apparent to them in the absence of sound. The effect of the type of camera movement in the scene (translation or rotation) on the viewers' perception of the motion smoothness/jerkiness was also investigated, but no significant association between them was found. Our results should lead to new insights in 3D graphics regarding the requirements for the delivered frame rate in a wide range of applications

The Effect of Music on the Perception of Display Rate and Duration of

It's currently impossible, even on modern graphics hardware to compute high fidelity graphics of complex scenes in real time. As we are producing the graphics for human observers it may be possible to exploit limitations of the human perceptual system to improve the quality/rendering time ratio. When confronted with multisensory input the human has to divide his/her cognitive resources between the different sensory stimuli. This paper presents an independent samples experiment on the influence of musical tempo and emotional suggestiveness of music on the perception of motion and time duration in a computer graphics environment. The purpose of this work is to investigate whether music would be a significant distractor, allowing us to render at a slower frame rate without any perceivable difference for the user. No overall main effect of fast tempo/exciting music was revealed, while slow tempo/relaxing music resulted in longer duration estimations and slower perceived temporal rates

Auditory bias of visual attention for perceptually-guided selective rendering of animations

The developers and users of real-time graphics, such as games and virtual reality, are demanding ever more realistic computer generated images. Despite the availability of modern graphics hardware, such real-time high fidelity graphics is still not feasible on a single PC. Research on visual perception has shown that the perceived quality of rendered graphics depends not only on the fidelity of the generated imagery but also on the characteristics of visual attention and the limitations of the human visual system. The findings of this research have been used to define perceptually driven criteria for rendering with the aim to reduce rendering times. Furthermore, in reality there are strong crossmodal interactions between auditory and visual stimuli, with a number of studies showing that stimuli reaching the various senses are not, in general, processed independently. In this paper we investigate whether auditory stimuli, and more specifically sound effects with abrupt onsets, affect a viewer's perceived quality of rendered images while watching computer generated animations. In fact, we show how we can potentially accelerate the rendering of animations by directing the viewer's attention towards the source of a sound and selectively render at high quality only the sound emitting object. For this purpose a renderer was implemented which selectively renders the sound emitting objects and the surrounding pixels to high quality while the rest of the scene is rendered at a significantly lower quality. A psychophysical experiment with 120 participants was run which revealed a significant effect of sound effects on the perceived rendering quality. Our results show that audio stimuli, and in particular sound effects, can be exploited when rendering animations, to significantly reduce rendering time without any loss in the user's perception of delivered quality

The Influence of Sound Effects on the Perceived Smoothness of Rendered Animations

The developers and users of interactive computer graphics (CG), such as 3D games and virtual reality, are demanding ever more realistic computer generated imagery delivered at high frame rates, to enable a greater perceptual experience for the user. As more computational power and/or transmission bandwidth are not always available, special techniques are applied that trade off fidelity in order to reduce computational complexity, while trying to minimise the perceptibility of the resulting visual defects. Research on human visual perception has promoted the development of perception driven CG techniques, where knowledge of the human visual system and its weaknesses are exploited when rendering/displaying 3D graphics. It is well known in the human perception community that many factors, including audio stimuli, may influence the amount of cognitive resources available to perform a visual task. In this paper we investigate the influence sound effects have on the perceptibility of motion smoothness in an animation (i.e. on the perception of delivered frame rate). Forty participants viewed pairs of computer-generated walkthrough animations (with the same visual content within the pair) displayed at five different frame rates, in all possible combinations. Both walkthroughs in each test pair were either silent or accompanied by sound effects and the participant had to decide which one had a smoother motion. A significant effect of sound effects on the perceived smoothness was revealed. The participants who watched the audiovisual walkthroughs gave more erroneous answers while performing their task compared to the subjects in the "No Sound" group, regardless of their familiarity with animated CG. Especially the unfamiliar participants failed to notice motion smoothness variat..