USER EVALUATIONS OF CONTRAST-DOMINANT DISCOMFORT GLARE IN DIM DAYLIT SCENARIOS: PRELIMINARY FINDINGS

Discomfort glare metrics typically consider at least one of the two effects of discomfort glare - saturation and contrast - in their equation. The former occurs when there is an excessively bright glare source in the field of view, while the latter occurs when there is a high luminance ratio between the glare source and the adaptation level of the eye. We hypothesize that the contrast effect may dominate in low-light scenarios such as those commonly found in open-plan offices. Thus, we designed and carried out a user study in controlled laboratory conditions with 63 participants with a total of 252 scenes to investigate discomfort glare evaluations in dim daylight office environments with low adaptation levels. Our preliminary findings support our hypothesis that contrast-driven metrics predict glare responses in a more reliable way than hybrid metrics at low adaptation levels where the contrast effect dominates, which underlines the need for refining glare metrics in low brightness conditions.

ON SENSITIVITY TO GLARE AND ITS RELATIONSHIP WITH MACULAR PIGMENT

Current trends in discomfort glare research have suggested the influence of physiological parameters on individual glare perception. To this end, we hypothesize that a specific ocular physiology characteristic, namely the macular pigment (MP) in the retina, could have an influence on glare sensitivity, encouraged by recent findings from the literature that have shown that high MP levels were indicative of better visual performance. This study investigates whether a person’s sensitivity to glare could be somehow correlated to their macular pigment optical density (MPOD). We measured MPOD in 56 participants and compared it with their discomfort glare thresholds, which were determined psychophysically by exposing the participants to a series of lighting conditions varying in intensity. We found that the influence of MPOD on glare sensitivity is borderline significant with small effect size but does not follow intuition. Additional data will be required to validate and refine these initial findings.

A GENERIC GLARE SENSATION MODEL BASED ON THE HUMAN VISUAL SYSTEM

Conventional discomfort glare measures are based on glare source properties like luminous intensity or luminance and typically are valid only to specific situations and to specific types of light sources. For instance, the Unified Glare Rating (UGR) is intended for indoor lighting conditions with medium-sized glare sources, whereas another class of discomfort glare measures is specifically devoted to car headlamps. Recently, CIE TC 3-57 started with the aim to develop a more generic glare sensation model based on the human visual system. We present an example of such a model, including a detailed description of aspects like pupil constriction, retinal image formation, photoreceptor response and adaptation, receptive field-type filtering in the retina, and neural spatial summation. The linear correlation of the model to UGR in an indoor setting, and to subjective glare responses in an outdoor-like setting indicate that the human-visual-system-based model may indeed be considered generic.

ILLUMINANCE AT THE EYE AS A SIMPLE METRIC FOR DISCOMFORT GLARE FROM PEDESTRIAN SCALE LUMINAIRES

In outdoor environments after dark, pedestrians may experience discomfort from road lighting. Previous studies have therefore developed models to predict discomfort from glare in pedestrian applications. However, the performance of these models has not been comprehensively assessed, and measurement challenges arise in field evaluations. This paper evaluates the performance of a model proposed by Bullough et al (2008) and compares it to prediction using only direct illuminance at the eye. Diagnostic metric tests were conducted using three independent datasets from previously published studies. The results suggested that direct illuminance at the eye performed similarly to the Bullough et al. model over the range of lighting conditions examined. These conditions included one glare source that contributed between 4 lx - 82 lx, and a low contribution from indirect illuminance and other lighting installations 1 lx - 4 lx. Further studies are needed to examine the importance of incorporating indirect illuminance from source and ambient illuminance for predicting discomfort glare.

Maximum Luminances and Luminance Ratios and their Impact on Users' Discomfort Glare Perception and Productivity in Daylit Offices: Testing the Hypothesis: Maximum Luminance and Ratio Recommendations For Visual Comfort Should be Specific to the Luminous Conditions and by Accounting For the Impact of Adaptation, the Recommendations Will be More Accurate.

<p>Lighting is an important environmental factor when considering health and safety, visual comfort and workplace design. But how well do we really understand the implications of lighting on these factors, especially in a workplace environment? When one attempts to digest the enormous volume of information of the past century regarding recommended lighting conditions, one begins to see that these recommendations are varied, not extensively tested and often apply to a very limited set of luminous conditions. In a world with daylighting design which increasingly challenges creative and technological boundaries, it is important that the factors and limits which contribute to visual comfort are well understood in order to test these new designs. Daylighting design also becomes important simply from a sustainability standpoint with energy efficiency becoming increasingly important in this age of diminishing natural resources. With an increase in the amount of daylight in buildings spawning from this desire to capitalize on the free and daily renewable light from the sun, difficult and often immeasurable factors such as a view of the outdoors and higher adaptation levels of space users' eyes could very realistically affect the current limits of the human visual system for visual comfort. Visual comfort, limits, which at best are ball park figures, loosely understood and rarely adhered to. This paper documents the testing of 48 test subjects, all of an age where they could feasibly be expected to work in an office environment, in a simulated contemporary office environment with a simulated daylighting window where the luminous conditions and layout were altered to assess the impact of such changes on visual comfort, productivity and different types of user characteristics. The window is designed so luminances of the window can be changed at will. By comparing subjective assessments of the lighting conditions with test performances, a greater understanding of the luminance limits (maximums and ratios) of the human eye for different contemporary lighting layouts within working-aged populations can be defined. With improved understanding of human tolerances to luminance distributions and lighting conditions which romote visual comfort and productivity, designers can begin to give glare prediction with respect to likely effects on these factors. This information would be highly valuable to office based firms who are currently building new or retrofitting premises (to the point where they would likely pay for it as an investment for future efficiency of their firms) thereby proving beneficial to demand for skilled architects, interior and lighting designers. In comparison to the relatively more complicated glare prediction indices involving various factors and calculations, luminance ratio recommendations are an easy to understand tool which with further study could become a powerful method of site and even user-specific glare prediction in the future.</p>

Maximum Luminances and Luminance Ratios and their Impact on Users' Discomfort Glare Perception and Productivity in Daylit Offices: Testing the Hypothesis: Maximum Luminance and Ratio Recommendations For Visual Comfort Should be Specific to the Luminous Conditions and by Accounting For the Impact of Adaptation, the Recommendations Will be More Accurate.

<p>Lighting is an important environmental factor when considering health and safety, visual comfort and workplace design. But how well do we really understand the implications of lighting on these factors, especially in a workplace environment? When one attempts to digest the enormous volume of information of the past century regarding recommended lighting conditions, one begins to see that these recommendations are varied, not extensively tested and often apply to a very limited set of luminous conditions. In a world with daylighting design which increasingly challenges creative and technological boundaries, it is important that the factors and limits which contribute to visual comfort are well understood in order to test these new designs. Daylighting design also becomes important simply from a sustainability standpoint with energy efficiency becoming increasingly important in this age of diminishing natural resources. With an increase in the amount of daylight in buildings spawning from this desire to capitalize on the free and daily renewable light from the sun, difficult and often immeasurable factors such as a view of the outdoors and higher adaptation levels of space users' eyes could very realistically affect the current limits of the human visual system for visual comfort. Visual comfort, limits, which at best are ball park figures, loosely understood and rarely adhered to. This paper documents the testing of 48 test subjects, all of an age where they could feasibly be expected to work in an office environment, in a simulated contemporary office environment with a simulated daylighting window where the luminous conditions and layout were altered to assess the impact of such changes on visual comfort, productivity and different types of user characteristics. The window is designed so luminances of the window can be changed at will. By comparing subjective assessments of the lighting conditions with test performances, a greater understanding of the luminance limits (maximums and ratios) of the human eye for different contemporary lighting layouts within working-aged populations can be defined. With improved understanding of human tolerances to luminance distributions and lighting conditions which romote visual comfort and productivity, designers can begin to give glare prediction with respect to likely effects on these factors. This information would be highly valuable to office based firms who are currently building new or retrofitting premises (to the point where they would likely pay for it as an investment for future efficiency of their firms) thereby proving beneficial to demand for skilled architects, interior and lighting designers. In comparison to the relatively more complicated glare prediction indices involving various factors and calculations, luminance ratio recommendations are an easy to understand tool which with further study could become a powerful method of site and even user-specific glare prediction in the future.</p>

Dynamic Autonomous Identification and Intelligent Lighting of Moving Objects with Discomfort Glare Limitation

The importance of reducing discomfort glare during the dynamic development of high luminance LEDs is growing fast. Smart control systems also offer great opportunities to reduce electricity consumption for lighting purposes. Currently, dynamic “intelligent” lighting systems are a rapidly developing field. These systems, consisting of cameras and lighting units, such as moving heads or multimedia projectors, are powerful tools that provide a lot of opportunities. The aim of this research is to demonstrate the possibilities of using the projection light in dynamic lighting systems that enable the reduction of discomfort glare and the light pollution phenomenon. The proposed system allows darkening or reducing the luminance of some sensitive zones, such as the eyes or the head, in real-time. This paper explores the development of the markerless object tracking system. The precise identification of the position and geometry of objects and the human figure is used for dynamic lighting and mapping with any graphic content. Time measurements for downloading the depth maps, as well as for identifying the human body’s position and pose, have been performed. The analyses of the image transformation times have been carried out in relation to the resolution of the images displayed by the projector. The total computation time related to object detection and image display translates directly into the precision of fitting the projection image to a moving object and has been shown.

The Effect Of Display Brightness On Visual Function For Young And Old Drivers

Nowadays outdoor advertising displays have become popular. Bright displays near the roads could cause drivers to experience disability or discomfort glare, especially at night. Disability glare increases with age, but discomfort glare thresholds are independent of age. The aim of the study was to assess a luminance level of displays, which causes glare for younger and older subjects. 24 young subjects age of 20 to 24 years and 13 older subjects age of 55 to 69 years participated in the study. The task was by using the method of adjustment to find out the acceptable level of display brightness when the recognition of high (>90%) contrast objects was comfortable. Measurements were done in a photopic and mesopic lighting conditions. Results showed that discomfort glare were larger in mesopic than in photopic lighting conditions (p < 0.001) for both age groups. Preferred display brightness in both lighting conditions did not significantly differ between age groups (p > 0.05). We can conclude that discomfort glare thresholds for displays with textual elements are independent of age.

Laboratory testing of a high efficiency light redirection system

Automated daylight redirecting slat technologies are designed to divert sunlight into the living space. They have a distinct advantage in that they can be retracted and extended, and slat angles can be adjusted according to the solar geometry and sky conditions. This study aimed to explore the geometric and photometric properties of a novel high-efficiency light redirection system (LRS). The LRS prototypes were installed in the clerestory window in the south-facing window testbed office and monitored under real sun and sky conditions. Workplane illuminance, daylight delivery efficiency (DDE) and visual comfort were evaluated. A number of simulation studies were conducted to evaluate the LRS and compare the results to the laboratory tests. The study shows that the specular properties of the slats provided significantly higher work plane illuminance and DDE. All systems showed an acceptable discomfort glare, or daylight glare probability (DGP) lower than 0.35. The comparison of the laboratory test and computer simulation was conducted using a Radiance tool. The results show that, for specular slats, the mkillum method with plastic material provided accurate work plane illuminance compared to the measurement. All simulated DGP shows accurate results compared to the laboratory test.