Smoothness perception : investigation of beat rate effect on frame rate perception

Despite the complexity of the Human Visual System (HVS), research over the last few decades has highlighted a number of its limitations. These limitations can be exploited in computer graphics to significantly reduce computational cost and thus required rendering time, without a viewer perceiving any difference in resultant image quality. Furthermore, cross-modal interaction between different modalities, such as the influence of audio on visual perception, has also been shown as significant both in psychology and computer graphics. In this paper we investigate the effect of beat rate on temporal visual perception, i.e. frame rate perception. For the visual quality and perception evaluation, a series of psychophysical experiments was conducted and the data analysed. The results indicate that beat rates in some cases do affect temporal visual perception and that certain beat rates can be used in order to reduce the amount of rendering required to achieve a perceptual high quality. This is another step towards a comprehensive understanding of auditory-visual cross-modal interaction and could be potentially used in high-fidelity interactive multi-sensory virtual environments

Importance driven environment map sampling

In this paper we present an automatic and efficient method for supporting Image Based Lighting (IBL) for bidirectional methods which improves both the sampling of the environment, and the detection and sampling of important regions of the scene, such as windows and doors. These often have a small area proportional to that of the entire scene, so paths which pass through them are generated with a low probability. The method proposed in this paper improves this by taking into account view importance, and modifies the lighting distribution to use light transport information. This also automatically constructs a sampling distribution in locations which are relevant to the camera position, thereby improving sampling. Results are presented when our method is applied to bidirectional rendering techniques, in particular we show results for Bidirectional Path Tracing, Metropolis Light Transport and Progressive Photon Mapping. Efficiency results demonstrate speed up of orders of magnitude (depending on the rendering method used), when compared to other methods

Was Aristotle the founder of chemistry?

Aristotle has recently been construed as the founder of chemistry. Aristotle does give a detailed account of combination in Generation and Corruption that can be read as conforming to the kind of combination characteristic of modern chemistry. Nevertheless, to interpret Aristotle’s discussion as constituting the beginnings of, or opening the way to, chemistry is to misunderstand both Aristotle and chemistry

Aristotle: Critic or Pioneer of Atomism?

Aristotle is typically construed as a critic of atomism. He was indeed a critic of atomism of the extreme kind formulated by Democritus, according to which bulk matter is made of nothing other than unchangeable pieces of universal matter possessing shape and size and capable of motion in the void. However, there is a weaker kind of atomism involving the assumption that macroscopic substances have least parts which have properties sufficient to account for the properties of the bulk substances that they are least parts of. Insofar as atomism has been vindicated by modern science, it is the weaker version of atomism that has proved to be profitable. The beginnings of the weaker version of atomism are to be found in Aristotle. Far from being an opponent of atomism, there is a sense in which Aristotle was one of its pioneers

Aristotle on Atomism

Two kinds of atomism emerged in the philosophy off the Presocratics. One kind was devised as a response to Parmenides and involved indivisible physical atoms. The other kind emerged in response to Zeno’s paradoxes and involved indivisible magnitudes that served as a barrier to the infinite division that led to those paradoxes. I argue, contrary to a range of positions to be found in the literature that Aristotle was aware of the distinction between the two kinds of atomism, did not attribute an atomism involving indivisible magnitudes to Democritus, and countered the two kinds of atomism with distinct kinds of arguments

Aristotle on Homoeomerous Substances

Aristotle’s characterisation of homoeomerous substances in Generation and Corruption is typically interpreted as involving the idea that such substances retain their identity as such however far they are divided. Yet, in Meteorology 4 Aristotle attributes properties of homoeomerous substances to a structure of corpuscles separated by pores. I suggest the clash between these two views is removed once it is appreciated that the position in Generation and Corruption does not involve indefinite division, as is typically supposed. Aristotle’s construal of homoeomerous substances, on my interpretation, is an important part of his attempt to make conceptual sense of the notion that all terrestrial substances are combinations of air, earth, fire and water

HDR video past, present and future : a perspective

High Dynamic Range (HDR) video has emerged from research labs around the world and entered the realm of consumer electronics. The dynamic range that a human can see in a scene with minimal eye adaption (approximately 1,000,000: 1) is vastly greater than traditional imaging technology which can only capture about 8 f-stops (256: 1). HDR technology, on the other hand, has the potential to capture the full range of light in a scene; even more than a human eye can see. This paper examines the field of HDR video from capture to display; past, present and future. In particular the paper looks beyond the current marketing hype around HDR, to show how HDR video in the future can and, indeed, should bring about a step change in imaging, analogous to the change from black and white to colour

Selective rendering for efficient ray traced stereoscopic images

Depth-related visual effects are a key feature of many virtual environments. In stereo-based systems, the depth effect can be produced by delivering frames of disparate image pairs, while in monocular environments, the viewer has to extract this depth information from a single image by examining details such as perspective and shadows. This paper investigates via a number of psychophysical experiments, whether we can reduce computational effort and still achieve perceptually high-quality rendering for stereo imagery. We examined selectively rendering the image pairs by exploiting the fusing capability and depth perception underlying human stereo vision. In ray-tracing-based global illumination systems, a higher image resolution introduces more computation to the rendering process since many more rays need to be traced. We first investigated whether we could utilise the human binocular fusing ability and significantly reduce the resolution of one of the image pairs and yet retain a high perceptual quality under stereo viewing condition. Secondly, we evaluated subjects' performance on a specific visual task that required accurate depth perception. We found that subjects required far fewer rendered depth cues in the stereo viewing environment to perform the task well. Avoiding rendering these detailed cues saved significant computational time. In fact it was possible to achieve a better task performance in the stereo viewing condition at a combined rendering time for the image pairs less than that required for the single monocular image. The outcome of this study suggests that we can produce more efficient stereo images for depth-related visual tasks by selective rendering and exploiting inherent features of human stereo vision

Multi-Sensory Virtual Environments for Investigating the Past

[EN] A human depends on all five senses: visuals, audio, smell, taste and touch to perceive an environment. It is not only the individual senses, but also their interaction that plays a key role in enabling us to understand the world around us. Virtual archaeology is being increasingly used to investigate the past. Failure to consider all senses in these reconstructions runs the very real danger of misrepresenting ancient environments and how they may have been perceived by our ancestors. This paper describes Real Virtuality: true high-fidelity multi-sensory virtual environments, and shows how such an approach may give historians a more valid means of considering the past.[ES] Los seres humanos dependemos de los cinco sentidos: vista, oído, olfato, gusto y tacto para percibir el medio ambiente. Estos sentidos y la interacción que se produce entre ellos es lo que desempeña un papel clave en la comprensión del mundo que nos rodea. La Arqueología virtual cada vez se utiliza más para investigar el pasado. Por ello si no tomamos en consideración todos los sentidos a la hora de realizar reconstrucciones virtuales corremos el peligro real de tergiversar los entornos antiguos y la forma en la que estos entornos pudieron haber sido percibidos por nuestros antepasados. Este artículo describe la Virtualidad Real: entornos virtuales multi-sensoriales de gran fidelidad, y muestra cómo este enfoque puede proporcionar a los historiadores un medio más válido para estudiar el pasado.Chalmers, A.; Zányi, E. (2010). Multi-Sensory Virtual Environments for Investigating the Past. Virtual Archaeology Review. 1(1):13-16. https://doi.org/10.4995/var.2010.4750OJS131611AGGLETON, J., AND WASKETT, L. (1999): "The ability of odours to serve as state-dependent cues for real-world memories: Can Viking smells aid the recall of Viking experiences? 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