Blur in Human Vision and Increased Visual Realism in Virtual Environments
A challenge for virtual reality (VR) applications is to increase the realism of an observer’s visual experience. For this purpose the variation of the blur that an observer experiences in his/her vision, while he/she focuses on a particular location, can
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Abstract. A challenge for virtual reality (VR) applications is to increase the realism of an observer’s visual experience. For this purpose the variation of the blur that an observer experiences in his/her vision, while he/she focuses on a particular location, can be mimicked by blurring the VR computer graphics based on a model of the blur. The blur in human vision is the result of a combination of optical and neural vision processes; namely optical refraction, nonuniform retinal sampling, and cortical magnification. Due to the complexity of the phenomenon, apparently no theoretical model of the blur has been published. In this work we model the combined effect by means of a probabilistic model of the human visual system. The results from the models match common vision experience verifying the validity of the underlying theoretical considerations. The implementation of the model for increased realism in virtual reality is illustrated by means of a rendering of a virtual reality scene, which is processed for two different acts of focusing.
1 Introduction Traditional applications of virtual reality (VR) are medical surgery training, flight and driving simulation, as well as industrial and architectural design [1, 2]. In the applications usually a high degree of visual realism is desired for increased effectiveness. Visual realism concerns both, the experienced egocentric and exocentric distances, and the level of visual detail of the environment. A source reducing visual realism of VR experience is the fact that a virtual scene is usually rendered on a 2-dimensional display, so that an observer has some awareness of the display surface [3]. There is evidence that awareness of the display surface interferes with the perceived threedimensionality of a scene displayed [4, 5]. This evidence appears to corroborate with experiments where absolute egocentric distances are found to be generally underestimated in VR [6, 7], while a number of possible reasons for this can be ruled out [8, 9], including the quality of the computer graphics as claimed by [10]. The visual experience of an object differs from the experience of the object’s counterpart in VR. One difference is the experienced variation of visual detail on the object when we focus our vision to a certain location on it. This phenomenon we refer to as blur phenomenon. When we focus on a surface patch S1 of an object, we experience the patch as visually sharp. When we keep focusing on S1, we experience another patch S2 located at some distance from S1 as less sharp, i.e. blur. The degree of experienced blur depends on the geometric relation among S1, S2, and the location of G. Bebis et al. (Eds.): ISVC 2007, Part I, LNCS 4841, pp. 137–148, 2007. © Springer-Verlag Berlin Heidelberg 2007
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M.S. Bittermann, I.S. Sariyildiz, and Ö. Ciftcioglu
observation. We can verify this by increasing the distance between S2 and S1, while we continue to focus on S1. When we experience an environment in virtual reality we obtain the visual information looking at the surface of th
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