28‐1: Invited Paper : Why Focus Cues Matter

Focus cues play a significant role in three-dimensional (3-D) depth perception. Conventional stereoscopic displays, however, lack the ability to correctly render these cues, because they present a pair of stereoscopic images on a fixed image plane while forcing the eyes to converge at different distances to view objects at different depths. Using a fast liquid-lens device, we present the design and implementation of a time-multiplexed dual-focal plane display that is capable of rendering correct or near-correct focus cues as well as other depth cues, such as occlusion and shading for a 3-D scene. The focus range of the dual focal planes can vary from infinity to as close as 8 diopters. Two driving mechanisms are proposed to render near-correct focus cues and their effects on image sharpness, flicker, and brightness are compared.

Stereoscopic displays provide viewers with stereoscopic images that are easily viewable. It is necessary to adjust the binocular disparity of a three-dimensional image to the allowable disparity range of a stereoscopic display. In this paper, we propose a method of adjusting the depth of field of binocular cameras in order to extract objects in the allowable disparity range. We develop a stereoscopic display system that enables the adjustment of the depth of field of binocular cameras. We have analyzed the disparity distribution and boundary of stereoscopic vision and discussed the most effective use of reproducible depth. Furthermore, the viewability of stereoscopic images taken at different depths of field was evaluated by a pair-comparison method. The experimental results showed that control of the depth of field is effective in leading a viewer's gaze to specific objects within the reproducible depth.

This paper describes a task-oriented approach to cope with the difference between the three dimensional (3D) space in a virtual reality (VR) system and that perceived by the user from its stereoscopic images with binocular disparity. This difference occurs for the reason that human visual perception is affected not only by binocular disparity but also by various kinds of visual cues. Although it is possible to set some of those cues consistent with each other when they are presented by a stereoscopic display, it is difficult to do the same for other cues especially vergence and focus. As the result, the users of VR systems often fail to manipulate virtual objects due to this difference. In this article, we propose to adjust the virtual space in a VR system through object manipulation by the user so that the user does not fail in each manipulation. We verified by experiments that this adjustment is effective to improve the rate of successful manipulation.

Visual comfort is a subjective aspect related to road-lighting quality. If the degree of visual comfort is not good enough, a motorist’s level of fatigue will increase and as a consequence, his visual performance and alertness will decrease. So both visual comfort and visual performance are important for road safety. Subjective appraisal studies have shown that the lighting level, the uniformity of the roadsurface luminance pattern and glare have an influence on visual comfort. The same type of studies have been the basis for definitions of visual comfort metrics such as longitudinal uniformity, luminance gradient and discomfort glare marks. The spectrum of the light source used has an influence on the last mentioned. LEDs may sometimes have a special influence on visual comfort because they are available in a much wider range of spectra than are the conventional light sources. Their small light-emitting surfaces enable more pronounced beams to be produced, that in turn may influence visual comfort or discomfort. Most LED luminaires consist of a multiple array of small LEDs resulting in a non-uniform luminance distribution of the light-emitting surface, which may have an influence on their discomfort glare aspect.

In the natural world, a number of visual cues indicate that an item is quickly approaching the perceiver. Binocular disparity is one cue for depth, and it has been demonstrated that abrupt changes in disparity, artificially unaccompanied by correlated depth cues, are capable of causing the perception of looming for the observer. An experiment involving 38 undergraduates, using a computer-controlled stereoscopic display, examined the ability of above-threshold changes in disparity (artificial looming) to facilitate response time and accuracy for observers engaged in an object-enumeration task within a cluttered display. Compared with performance using the same stimuli without disparity information (lateral motion), participants were more accurate regardless of the disparity level (9, 12, 24, or 48 minutes of arc) and faster at the two lowest levels of disparity. Participants showed the classic subitizing function, suggesting that target stimuli presented with motion information were segregated from otherwise identical distractor items. It is proposed that binocular disparity information can act as a valid location cuing method in stereoscopic computer displays in which form and color information are to be preserved.

BackgroundCeramic tiles are widely used in workplace environments, and their visual characteristics can influence users’ perceptual and cognitive experiences. However, research remains limited on how ceramic tile properties affect visual comfort, cognitive performance, and related neural responses.MethodThis study examines six common types of mass-produced ceramic tiles, employing virtual reality (VR) and electroencephalogram (EEG) technologies to evaluate visual comfort and cognitive performance. A 2 (patterned vs. non-patterned) × 3 (light-toned, medium-toned, dark-toned) factorial design was used to construct six immersive VR environments through 3D modeling. Data on visual comfort ratings, cognitive behavioral performance, and EEG responses were collected from participants in each environment. The effects of tile’s pattern and brightness on visual comfort, cognitive outcomes, and neural activity were analyzed.ResultThe findings indicate that environments with non-patterned and light-toned ceramic tiles received higher visual comfort ratings and elicited increased alpha wave power spectral density, reflecting positive emotional experiences. In terms of cognitive performance, the participants had shorter reaction durations in the environments of light-toned ceramic tiles and patterned ceramic tiles, and were negatively correlated with the beta wave power spectral density values.DiscussionThe results suggest that ceramic tile selection can be tailored to the functional needs of interior spaces. For instance, in relaxing settings such as lounges, tiles that enhance alpha-wave activity may be preferable, while in workspaces requiring high cognitive engagement--such as studios, meeting rooms, or offices--tiles that promote moderate beta-wave activity may be more suitable. This study provides valuable insights and evaluation methods for interior and ceramic tile designers, especially for design of Chinese region.

Discerning objects from their surrounds (i.e., figure-ground segmentation) in a way that guides adaptive behaviors is a fundamental task of the brain. Neurophysiological work has revealed a class of cells in the macaque visual cortex that may be ideally suited to support this neural computation: border ownership cells (Zhou H, Friedman HS, von der Heydt R. J Neurosci 20: 6594–6611, 2000). These orientation-tuned cells appear to respond conditionally to the borders of objects. A behavioral correlate supporting the existence of these cells in humans was demonstrated with two-dimensional luminance-defined objects (von der Heydt R, Macuda T, Qiu FT. J Opt Soc Am A Opt Image Sci Vis 22: 2222–2229, 2005). However, objects in our natural visual environments are often signaled by complex cues, such as motion and binocular disparity. Thus for border ownership systems to effectively support figure-ground segmentation and object depth ordering, they must have access to information from multiple depth cues with strict depth order selectivity. Here we measured in humans (of both sexes) border ownership-dependent tilt aftereffects after adaptation to figures defined by either motion parallax or binocular disparity. We find that both depth cues produce a tilt aftereffect that is selective for figure-ground depth order. Furthermore, we find that the effects of adaptation are transferable between cues, suggesting that these systems may combine depth cues to reduce uncertainty (Bülthoff HH, Mallot HA. J Opt Soc Am A 5: 1749–1758, 1988). These results suggest that border ownership mechanisms have strict depth order selectivity and access to multiple depth cues that are jointly encoded, providing compelling psychophysical support for their role in figure-ground segmentation in natural visual environments.NEW & NOTEWORTHY Figure-ground segmentation is a critical function that may be supported by “border ownership” neural systems that conditionally respond to object borders. We measured border ownership-dependent tilt aftereffects to figures defined by motion parallax or binocular disparity and found aftereffects for both cues. These effects were transferable between cues but selective for figure-ground depth order, suggesting that the neural systems supporting figure-ground segmentation have strict depth order selectivity and access to multiple depth cues that are jointly encoded.

It is important to acquire the proper parallax images for the stereoscopic display system. By setting the proper distance between the cameras and the location of the convergent point in this capturing configuration, the displayed 3D scene with the appropriate stereo depth and the expected effect in front of and behind the display screen can be obtained directly. The quantitative relationship between the parallax and the parameters of the capturing configuration with two cameras is presented. The capturing system with multiple cameras for acquiring equal parallaxes between the adjacent captured images for the autostereoscopic display system is also discussed. The proposed methods are demonstrated by the experimental results. The captured images with the calculated parameters for the 3D display system shows the expected results, which can provide the viewers the better immersion and visual comfort without any extra processing.

Human factors are of high importance in 3D visualization, but subjective evaluation of 3D displays is not easy because of a high variability among users. This study aimed to evaluate and compare two different 3D visualization systems (a market stereoscopic display, and a state-of-the-art multi-view display) in terms of user performance and quality of experience (QoE), in the context of interactive visualization. An adapted methodology has been designed in order to focus on 3D differences and to reduce the influence of all other factors. Thirty-six subjects took part in an experiment during which they were asked to judge the quality of their experience, according to specific features. Results showed that a scene understanding and precision was significantly better on the multi-view display. Concerning the quality of experience, visual comfort was judged significantly better on the multi-view display and visual fatigue was reported by 52% of the subjects on the stereoscopic display. This study has permitted to identify some factors influencing QoE such as prior experience and stereopsis threshold.

Depth perception is an important component of many augmented reality applications. It is, however, subject to multiple error sources. In this study, we investigated depth judgments with a stereoscopic video see-through head-mounted display for the purpose of designing depth cueing for systems that operate in an individual’s action space. In the experiment, we studied the use of binocular disparity and relative size to improve relative depth judgments of augmented objects above the ground plane. The relative size cue was created by adding auxiliary augmentations to the scene according to constraints described in the section on the underlying theory. The results showed that binocular disparity and relative size improved depth judgments over the distance range. This indicates that for accurate depth judgments, additional depth cues should be used to facilitate stereoscopic perception within an individual’s action space.

A head‐mounted light field display based on integral imaging is considered as one of the promising methods that can render correct or nearly correct focus cues and address the well‐known vergence‐accommodation conflict problem in head‐mounted displays. Despite its great potential, it still suffers some of the same limitations of conventional integral imaging‐based displays such as low spatial resolution and crosstalk. In this paper, we present a prototype design using tunable lens and aperture array to render 3D scenes over a large depth range while maintaining high image quality and minimizing crosstalk. Experimental results verify and show that the proposed design could significantly improve the viewing experience.

We present an optical mapping near-eye (OMNI) three-dimensional display method for wearable devices. By dividing a display screen into different subpanels and optically mapping them to various depths, we create a multiplane volumetric image with correct focus cues for depth perception. The resultant system can drive the eye's accommodation to the distance that is consistent with binocular stereopsis, thereby alleviating the vergence-accommodation conflict, the primary cause for eye fatigue and discomfort. Compared with the previous methods, the OMNI display offers prominent advantages in adaptability, image dynamic range, and refresh rate.

Lighting plays an important role in the Hospital Diagnostic and Treatment Room. It shall be environmentally and functionally suitable for three groups of people: patients, hospital professionals and visitors. On the other hand lighting is considered a major consumer of electrical energy and therefore, hospital lighting design should consider the visual performance, visual comfort and energy efficiency. This article discusses the performance of different types of lighting installations used for hospital lighting system design applications: first the visual comfort and second to save energy consumptions in such applications. DIALux 4.8 simulation software is used to study and evaluate the efficient lighting scheme for the hospitals through the use of different types of lamps. Also, visual environment lighting system design procedure is explained. Economics of different lighting scenarios are highlighted.

Immersive virtual and augmented reality systems (VR/AR) are entering the consumer market and have the potential to profoundly impact our society. Applications of these systems range from communication, entertainment, education, collaborative work, simulation and training to telesurgery, phobia treatment, and basic vision research. In every immersive experience, the primary interface between the user and the digital world is the near-eye display. Thus, developing near-eye display systems that provide a high-quality user experience is of the utmost importance. Many characteristics of near-eye displays that define the quality of an experience, such as resolution, refresh rate, contrast, and field of view, have been significantly improved in recent years. However, a significant source of visual discomfort prevails: the vergence-accommodation conflict (VAC). This visual conflict results from the fact that vergence cues, but not focus cues, are simulated in near-eye display systems. Indeed, natural focus cues are not supported by any existing near-eye display. Afforded by focus-tunable optics, we explore unprecedented display modes that tackle this issue in multiple ways with the goal of increasing visual comfort and providing more realistic visual experiences.

Adequate daylighting is a vital element of effective learning environments, profoundly affecting students' visual comfort, cognitive performance, and psychological well-being. Insufficient access to natural light not only hampers academic productivity but can also negatively impact the physical and mental health of occupants. In tropical climates such as Chittagong, Bangladesh, the design of educational buildings must strike a careful balance between daylight access and thermal comfort. While external shading devices play a crucial role in minimizing solar heat gain and glare, they can also obstruct daylight entry, potentially diminishing indoor lighting quality. This study explores how different configurations of external shading devices influence daylight performance in south-facing classrooms, using a typical classroom at the Chittagong University of Engineering and Technology (CUET) as a case study. A mixed-method approach was adopted, integrating on-site illuminance measurements with daylight simulation tools to evaluate the effectiveness of the existing shading strategies. Alternative shading configurations were subsequently proposed and analyzed to assess their impact on indoor daylight distribution. The findings indicate that carefully optimized shading geometries can enhance daylight penetration while maintaining acceptable thermal comfort levels, thus improving overall indoor environmental quality. This research provides evidence-based design recommendations for the integration of passive shading solutions in classroom architecture, aiming to assist architects and designers in creating sustainable, energy-efficient educational environments that support both visual comfort and occupant well-being in tropical regions.