Level of Detail (LoD) techniques for real-time... In this paper, we are particularly interested in the problem of realistic collision simulation in scenes where large numbers of objects are colliding and processing must occur in real-time. An interruptible and therefore degradable collision handling mechanism is used and the perceptual impact of this degradation is explored. We look for ways in which we can optimise the realism of such simulations and describe a series of psychophysical experiments that investigated different factors affecting collision perception, including eccentricity, separation, distractors, causality and accuracy of physical response. Finally, strategies for incorporating these factors into a perceptually adaptive real-time simulation of large numbers of visually similar objects are presented.

INTRODUCTION A growing number of people suffer from visual impairments. These impairments and the resulting disabilities greatly affect the quality of life of many older, otherwise healthy people. The rehabilitation needs of people with visual impairments cover a wide scope of activities including reading, face recognition, independent mobility, attending to daily activities, and watching television (TV). Traditionally, vision rehabilitation has been aimed at improving mobility and reading skills. The incorporation of computerized image enhancement to improve video images for people with visual impairments was first proposed by Peli and Peli. Although image enhancement may be used in portable mobility devices, 2,3 in the near future we see the main value of image enhancement in providing people with visual impairments with access to the growing volume of video images presented on stationary monitors. TV is an important means of obtaining information and sharing in our culture. S

The perceived contrast of a central stimulus can be decreased (surround suppression) or increased (surround facilitation) by the presence of surround stimuli. In this report we examined center-surround interactions in foveal and peripheral vision using contrast-matching tasks. We found that: (1) surround suppression became markedly stronger as the center-surround stimulus was moved toward the periphery; (2) surround facilitation diminished in the periphery; and (3) the suppression in the periphery was less orientation- and frequency-specific than that in the fovea, so that significant suppression was induced even when the central and surround gratings had very different orientations and spatial frequencies. The different center-surround interactions in the fovea and periphery can not be accounted for by cortical magnification, suggesting that center-surround interactions in the fovea and periphery are incommensurable and play different functional roles in human image processing. 2000 E...

this report is to study the variation of the slope of the psychometric function for character recognition versus pattern contrast, across the horizontal meridian, for binocular and monocular vision. A fine, 2-deg raster of horizontal eccentricities is used across the entire range to obtain a detailed description of any variation. The slope data at finely spaced retinal positions presented here should provide a firm basis on which to build future studies

Seven models of human visual recognition from cognitive psychology, visual psychophysics, and connectionism were compared. They were used to predict psychophysical classification data obtained via supervised learning with parametrised gray-level patterns (compound Gabor signals). Four sets of learning patterns as well as foveal and extrafoveal viewing conditions were applied. Model performance was determined by comparing observed and predicted data with respect to RMS deviation and to signal reconstruction via multidimensional scaling. Results show that a psychophysical theory of classification requires a similarity concept that is based both on physical signal description and on cognitive bias. The latter is less pronounced in foveal recognition, where all seven models performed almost equally well, but matters in extrafoveal recognition. Virtual prototype models (Rentschler et al. 1994, Vision Research 34, 669-687), which best accommodate stimulus- and observer-dependen...

In this chapter, we will discuss the usefulness of eye-tracking for computer applications that attempt to render simulations at interactive rates.