Evaluation Of Discomfort Glare Research Articles

Comparison of Simulation Methods for Glare Risk Assessment with Roller Shades

Daylight discomfort glare evaluation is important when selecting shading properties. New standards recommend allowable glare frequency limits but do not specify the modeling accuracy required for annual glare risk assessment. Fast simulation tools allow users to perform hourly glare evaluations within minutes. However, reliable evaluation of glare through roller shades requires accurate modeling of their specular and diffuse transmission characteristics, affected by color, materials, and weaving technology. This study presents a systematic comparison between commonly used glare simulation methods against the “ground truth” Radiance ray-tracing tool rpict in terms of hourly daylight glare probability (DGP), hourly vertical illuminance (Ev), and annual visual discomfort frequency. The results are presented for two shade fabrics using light transmission models with and without a peak extraction algorithm (Radiance–aBSDF and Radiance–BSDF) for the specular component. The impact of sky/sun discretization on glare prediction is also discussed. The results show that the Radiance 5–Phase Method (5PM) is superior when modeling direct sunlight and DGP through shades, while other investigated methods (3–Phase Method, imageless DGP, ClimateStudio Annual Glare) are not as robust for that purpose. Users are encouraged to understand the underlying assumptions in the imageless methods to avoid errors when simulating glare, especially due to the contrast effects.

Morphological and Position Factors of Vertical Surface Light Source Affecting Discomfort Glare Perception

Distinguished from conventional lighting, the LED vertical surface light source (VSLS) is directly exposed to human view, and the effects of which form it takes on visual perception are non-negligible. In the current discomfort glare evaluation system, the solid angle and the position index, which represent the relative relation between the glaring light source and human visual field, are not completely applicable for large-area VSLS, and hence are awaiting supplementation and modification. In this study, a physical experimental setup was established to conduct an evaluation experiment on discomfort glare, employing an LED display and white translucent frosted film to simulate vertical surface light sources (VSLS). The experiments were arranged with 21 VSLS shapes (comprising 3 areas and 7 length-to-width ratios) and 11 mounting positions. Subjective ratings and four eye-movement data parameters—namely, the change rate of pupil diameter (CRPD), mean saccadic amplitude (SA), blinking frequency (BF), and saccadic speed (SS)—were collected from 24 participants under each working condition using the Boyce Evaluation Scale and eye tracking techniques. The main results of this study are the following: (a) CRPD is the most appropriate eye-movement index for characterizing VSLS glare perception; (b) The area of the VSLS is the primary shape element influencing discomfort glare. Furthermore, with the same surface area, the lateral view angle (LaVA) and the longitudinal view angle (LoVA) perceived by the human eye also impact glare perception; (c) A functional equation between the VSLS area, LaVA, and LoVA to the borderline luminance between comfort and discomfort (BCD luminance) is fitted; (d) Based on the eccentric angle and the azimuthal angle, a modified position index P’ is proposed to represent the relative position of the VSLS in the visual field, and the ratio function of BCD luminance of the VSLS at non-central positions and the central position is fitted.

Experimental study on the impact of double tilted Venetian blinds on indoor daylight conditions

One of the most important concerns when designing buildings as liveable spaces is the indoor comfort. This depends on different factors, including daylight availability and discomfort glare conditions.The increasing use of glazing areas in the building's envelopes can lead to high energy consumption and problems such as visual discomfort. The use of shading devices stands out as a sustainable design strategy to reduce energy consumption in the buildings. This work presents an experimental analysis of the impact of an innovative shading device, a double-tilted venetian blind (DTVB) with different positions of upper and lower slats, on the indoor daylight conditions. Moreover, discomfort glare evaluation, through DGPs metric, is performed.The experimental campaign was conducted in an outdoor test cell during three periods of the year: summer solstice, winter solstice and autumn equinox. Experiments were carried out with both white and grey DTVBs, for several positions of upper and lower slats, under clear and overcast sky conditions. This comprises the measurement of indoor and outdoor horizontal and vertical illuminances and irradiances and solar and visible transmittance of the fenestration. It was concluded that DTVBs can achieve a higher performance, regarding solar protection, daylighting and glare control, when compared with more traditional venetian blinds systems.

Laser dazzler emitting three-colour radiation

The article presents a laser dazzle generating three overlapping laser beams of different colours and an analysis of the possibility of dazzling people with this radiation. The analysis took into account the eye’s photopic sensitivity and the additivity of the three radiation beams. Such analysis, to the knowledge of the authors, is presented for the first time. The possibility of dazzling for four different dazzle levels and three levels of ambient luminance was presented. It has been shown that in some conditions it is possible to damage the eye without causing the assumed dazzle effect. Full Text: PDF ReferencesJoint Non-Lethal Weapons Program, Non-Lethal Optical Distracters Fact Sheet, (2016). DirectLink https://www.faa.gov/about/initiatives/lasers/laws/ DirectLink N. Raoof, et al., "‘Toy’ laser macular burns in children", Eye 28, 231 (2014). CrossRef D. B. Gosling, J. B. O'Hagan, and F. M. Quhill, "Blue Laser Induced Retinal Injury in a Commercial Pilot at 1300 ft", Aerospace Medicine and Human Performance 87, 69 (2016). CrossRef J. Marshall, J. B. O'Hagan, and J. R. Tyrer, "Eye hazards of laser ‘pointers’ in perspective", Br. J. Ophthalmol. 100, 583 (2016). CrossRef N. Raoof, J. O'Hagan, N. Pawlowska, and F. Quhill, "Toy’ laser macular burns in children: 12-month update", Eye 30, 492 (2016). CrossRef S. Androudi and E. Papageorgiou, "Macular Hole from a Laser Pointer", New England Journal of Medicine 378, 2420 (2018) CrossRef J. E. Neffendorf, G. D. Hildebrand and S. M. Downes, "Handheld laser devices and laser-induced retinopathy (LIR) in children: an overview of the literature", Eye 33, 1203 (2019). CrossRef E. Linton, et al., "Retinal burns from laser pointers: a risk in children with behavioural problems", Eye 33, 492 (2019). CrossRef P. Dockrill, Science alert, (2020). DirectLink IEC 60825-1:2014, Safety of laser products - Part 1: Equipment classification and requirements (International Electrotechnical Commission 2014). DirectLink ANSI Z136.1-2014, American National Standard for Safe Use of Lasers (American National Standards Institute 2014). DirectLink C. A. Williamson and L. N. McLin, "Nominal ocular dazzle distance (NODD)", Appl. Opt. 54, 1564 (2015). CrossRef C. A. Williamson and L. N. McLin, "Determination of a laser eye dazzle safety framework", Journal of Laser Applications 30, 032010 (2018). CrossRef J. Mlynczak, K. Kopczynski, M. Kaliszewski, M. Wlodarski, "Estimation of nominal ocular hazard distance and nominal ocular dazzle distance for multibeam laser radiation", Applied Optics, 60(22), 6414-6421 (2021). CrossRef CVRL Database, CVRL functions, Luminous efficiency functions, 2-deg functions. DirectLink Peter Lennie, Joel Pokorny, and Vivianne C. Smith, "Luminance", Journal of the Optical Society of America A, 10 (6), 1283-1293, (1993) CrossRef H. Cai and T. Chung, "Evaluating discomfort glare from non-uniform electric light sources", Lighting Research & Technology, 45 (3), 267-294 (2012). CrossRef

Evaluation of Driver Discomfort Glare for Road Lighting in Adverse Weather by Utilizing UGR (Unified Glare Rating)

Evaluation of Driver Discomfort Glare for Road Lighting in Adverse Weather by Utilizing UGR (Unified Glare Rating)

Discomfort Glare Evaluation using DIALux Lighting Simulation software and using developed Python Program model

Glare is a visual sensation caused by excessive brightness. It is subjective and person dependent. So, it is very difficult to measure glare factor accurately. Glare can be disabling or uncomfortable. Disability glare is the reduction in vision caused by bright light sources and it can be increased with the age of a person. Discomfort glare is a sensation of irritation due to bright light sources. There are various methods to evaluate discomfort glare. These methods are discussed in this paper.
 This paper mainly focuses on two methods of discomfort glare evaluation; Unified Glare Rating (UGR) and Daylight Glare Probability (DGP). These glare factors are calculated by using DIALux lighting simulation software and by using developed program. The experimentation was carried out in two different spaces; Conference room and Optoelectronics laboratory. The values of UGR, daylight factor are calculated by using DIALux and developed program. The comparison of the results obtained is discussed at the end of this paper.

Daylight Discomfort Glare Evaluation with Evalglare: Influence of Parameters and Methods on the Accuracy of Discomfort Glare Prediction

Nowadays, discomfort glare indices are frequently calculated by using evalglare. Due to the lack of knowledge on the implications of the methods and parameters of evalglare, the default settings are often used. But wrong parameter settings can lead to inappropriate glare source detection and therefore to invalid glare indices calculations and erroneous glare classifications. For that reason, this study aims to assess the influence of several glare source detection methods and parameters on the accuracy of discomfort glare prediction for daylight. This analysis uses two datasets, representative of the two types of discomfort glare: saturation and contrast glare. By computing three different statistical indicators to describe the accuracy of discomfort glare prediction, 63 different settings are compared. The results suggest that the choice of an evalglare method should be done when considering the type of glare that is most likely to occur in the visual scene: the task area method should be preferred for contrast glare scenes, and the threshold method for saturation glare scenes. The parameters that should be favored or avoided are also discussed, although a deeper understanding of the discomfort glare mechanism and a clear definition of a glare source would be necessary to reliably interpret these results.

A proposed discomfort glare evaluation method based on the concept of 'adaptive zone'

Glare is position and view direction-dependent within a space, but most visual comfort analysis is taken place in a fixed position and view direction. Allowing occupant to rotate view direction or shift seat position to avoid glare will reduce the degree of discomfort perceptions. Such view direction rotation and position shifting range so-called ‘adaptive zone’. The aim of the paper is to acquire the extent of the reduction in predicting glare when considered the ‘adaptive zone’. The research objects are an office room with three façade types, and all the simulation data are generated from radiance-based visualization renderings, which is implemented by DIVA for Grasshopper plus rhino. The simulations are carried out on Summer and Winter solstices and autumnal equinox under Perez sky model. For the façade without shading, the mean glare reduction is 18.7%/28.4%/35.1% if the rotation freedom allowed within ±15°/±30°/±45° and permitting the seat position move about 0.5 m respectively; For the overhang variant, the result is 17.5%/26.2%/31.5%; For the lightshelf variant in this study, the result is 14.6%/22.7%/27.7%; The introduction of the concept of ‘adaptive zone’ in visual comfort predictions significantly reduces both the degree and the occurring time of discomfort glare. Continuous glare analysis based on a moveable view is a beneficial for studying the visual comfort issues rigorously which related to the occupant behavior in an interior space. The concept of ‘adaptive zone’ provides a reasonable idea to deal with the confusion of view direction in visual comfort detect cases.

Effects of Mounting Height, Offset Distance, and Number of Light Towers on Drivers’ Visual Performance and Discomfort Glare in Work Zones

Portable light towers are a significant source of glare to motorists entering a work zone. Although existing research has evaluated the effect of light tower orientation on visibility and glare, the effects of factors like mounting height, offset distance from the roadway, and number of light towers in the work zone, on visual performance and discomfort glare is not known. Understanding these relationships can help in developing illuminating guidelines for work zones that can reduce glare for drivers. The goal of this paper is to understand the effect of mounting height, offset distance to the roadway, and number of light towers in the work zone on drivers’ visual performance and discomfort glare. Participants drove through a realistic work zone and evaluated portable light towers in varying mounting heights, offset distances, and number of light towers in the work zone. Results showed that the mounting height and offset distances play a critical role in affecting the driver’s visual performance and discomfort glare rating. Portable light towers, irrespective of wattage and lumen output, at lower than a mounting height of 20 ft and closer to the roadway result in decreasing driver visual performance and increasing their discomfort glare. Portable light towers should be mounted at a height of at least 20 ft and balloon light towers with higher wattage (4,000 W and greater) and lumen output (400,000 lumens and greater) should be located at an offset distance of at least 10 ft from the roadway.

Correspondence: New methods for the evaluation of discomfort glare

Correspondence: New methods for the evaluation of discomfort glare

A Simple Method to Improve VCP by Reducing DGR in an Interior Lighting Installation

Discomfort glare rating (DGR) and Unified glare rating (UGR) are main models currently used as discomfort glare evaluation systems, both of which are calculated employing four factors including the luminaire size, the luminaire position relative to the observer, background luminance, and the luminaires number and location. This study aims at proposing a simple solution for reducing DGR and thereby increasing visual comfort perception (VCP) in an interior lighting system. The proposed solution is based solely on variations of luminaire surface area without change in other factors, e.g. candlepower and number and location of luminaires in the lighting system. To this end, firstly, the equations related to DGR were modified for a desired luminaire, and, secondly, by solving the modified equations, the new luminaire surface area was obtained, which caused DGR decrease and VCP improvement. Finally, by some modifications in the location of selected luminaires having main role on DGR, the VCP rose considerably.

Discomfort glare evaluation: The influence of anchor bias in luminance adjustments

Luminance adjustment is a procedure commonly used to evaluate discomfort glare and the results from adjustment experiments form the basis of some recommendations for limiting its occurrence. There are, however, strong reasons to expect that settings made using adjustment are unintentionally influenced by extraneous variables. This paper discusses bias towards the initial anchor, the setting of the variable stimulus immediately before an adjustment is made. Specifically, the initial luminance is expected to influence the setting that is made by adjustment; for example, a lower initial luminance leads to a lower setting than a high initial luminance. To investigate anchor bias, a Hopkinson-like multiple-criterion adjustment experiment was undertaken, but with three different anchors. The results confirmed significant bias: glare settings were biased towards the luminance of the initial anchor. This demonstrates a need for caution when using adjustment to explore discomfort glare and when interpreting the results of past studies that used discomfort glare models fitted to data obtained with this procedure.

Survey of discomfort glare from the headlamps of cars widely used in Iran

ABSTRACTObjective: On 2-lane roads, discomfort glare can cause annoyance, discomfort, inconvenience, stress, and fatigue to drivers, posing a risk of accidents. The aim of this study is to evaluate discomfort glare from the headlamps of cars widely used in Iran.Methods: The discomfort glare of new vehicles including Pride Saba model GTX, Pride Model 131SL, Samand Soren, Peugeot 405, Megane, and Peugeot Pars was examined at distances of 5 to 100 m at a background luminance of 50 cd/m2 (late twilight/early dawn lighting) and 1 cd/m2 (nighttime) using Schmidt-Clausen and Bindels model and de Boer's subjective scale.Results: According to the de Boer scale, at a background luminance of 50 cd/m2, the discomfort glare for all studied vehicles was between 1.98 and 4.05 in high-beam mode and between 3.5 and 5.4 in low-beam mode. At a background luminance of 1 cd/m2, discomfort glare was between 0.41 and 2.48 in high-beam mode and between 1.93 and 3.84 in low-beam mode. In high-beam mode, the average levels of discomfort glare of these vehicles gradually increased when the distance between cars was reduced by up to about 20 m. In low-beam mode, there was no discomfort glare up to a vehicle distance of 40 m. In addition, at an angle of 1.15°–5.73° between the line of sight and light of vehicles in high-beam mode, the level of discomfort glare was increased, but at an angle of 5.73°–22.9° the level of discomfort glare was reduced. In low-beam mode at an angle of 2.86°–22.9°, the level of discomfort glare was almost identical. The results show that in high-beam mode and with a 100-m distance between vehicles as well as in low-beam mode at intervals of less than 40 m between cars, discomfort glare is created.Conclusion: It can be concluded that by providing solutions such as installing road lighting system, an increase in luminance of roads, separating or widening road lanes, increasing the lateral distance between vehicles, and increasing the angle between lighted vehicles and drivers can noticeably reduce discomfort glare.

Preliminary evaluation of discomfort glare from organic light-emitting diode and edge-lit light-emitting diode lighting panels.

The organic light-emitting diode (OLED) is an area light source, and its primary competing technology is the edge-lit light-emitting diode (LED) panel. Both technologies are similar in shape and appearance, but there is little understanding of how people perceive discomfort glare (DG) from area sources. The objective of this study was to evaluate the DG of these two technologies under similar operating conditions. Additionally, two existing DG models were compared to evaluate the correlation between predicted values and observed values. In an earlier study, we found no statistically significant difference in human response in terms of DG between OLED and edge-lit LED panels when the two sources produced the same luminous stimulus. The range of testing stimulus was expanded to test different panel luminances at three background illuminations. The results showed no difference in perceived glare between the panels, and, as the background illumination increased, the perceived glare decreased. In other words, both appeared equally glary beyond a certain luminance and background illumination. We then compared two existing glare models with the observed values and found that one model showed a good estimation of how humans perceive DG. That model was further modified to increase its power.

実装密度が異なる白色 LED 光源の明るさ評価

Light-emitting diode (LED) light sources are increasingly being used. One LED light source is composed of many small LED chips, so the luminance distribution varies depending on the number and arrangement of the LED chips. Quantitative relationships between non-uniform light sources, such as LEDs, and discomfort glare rating have been widely reported, but the relationship between the non-uniform light sources and the perception of brightness has not been clarified.

自動車用赤色 LED 灯体の不快グレア評価予測

自動車用赤色 LED 灯体の不快グレア評価予測

Assessing and Modeling Discomfort Glare for Raw White LEDs with Different Patterns

ABSTRACTThis article describes an experiment carried out to evaluate discomfort glare of nonuniformly distributed light emitting diode (LED) sources. The glare sources were created with a 4 × 4 LED panel. Twenty participants evaluated 140 lighting conditions consisting of eight nonuniformity patterns, four to five levels of luminous intensity, two levels of background luminance, and two angles above the line of sight. Some clear trends were found: discomfort glare was greater when the light source was less uniform and with higher LED luminous intensity, darker background, or a smaller angle above the line of sight. The unified glare rating (UGR) model for small glare sources (UGRsmall) was tested using the experimental data. Although the UGR model had good correlation with visual results, it underestimated perceived glare. In addition, the degree of uniformity of the glare source was found to influence the performance of UGRsmall. As nonuniformity increases, the performance of UGRsmall decreases. Three modified versions of UGRsmall were derived, where each of the proposed models better predicts discomfort glare from nonuniform raw LED glare sources.

A neural response-based model to predict discomfort glare from luminance image

It is well known that one of the problems of the current method for discomfort glare evaluation, called the unified glare rating, is the non-uniform luminance of the glare source. This paper addresses this issue by considering the spatial contrast of luminance as a measure of non-uniformity. An image-based metric is proposed to evaluate discomfort glare by modeling the neural response of human vision. The model takes an absolute luminance image as input and predicts visual discomfort based on the spatial distribution of the luminance of the stimulus and the background. The developed model was tested to predict subjective glare ratings based on an experiment conducted using non-uniform LED sources with symmetric and asymmetric patterns of LEDs, and its performance was compared with the unified glare rating. As expected, the unified glare rating predictions correlated well with the subjective glare evaluations of luminaires with symmetric patterns of LEDs (as they appear less non-uniform) but not for those with asymmetric patterns. Results showed that the developed model, named the Neural Response-based Glare Model, gave similar performance to unified glare rating for symmetric patterns but outperformed UGR for asymmetric patterns of LEDs.

SELECTED METROLOGY PROBLEMS IMPLIED BY THE APPLICATION OF LED TECHNOLOGY IN LIGHTING

High power LEDs replace traditional light sources in all possible lighting applications, causing significant problems in assessing the quality of lighting. This issue is not limited only to the construction aspects of the measuring equipment, but also has a cognitive dimension. The article presents an overview of the current state of knowledge on color rendering and evaluation of discomfort glare in relation to the widespread use of LEDs in lighting. Some selected parameters developed copyright sources with LED sets. Basic limitations in UGR measurement were indicated.

Absolute glare factor and relative glare factor based metric: Predicting and quantifying levels of daylight glare in office space

Extensive human subject research was performed to develop a daylight glare analysis methodology that correlates the Absolute Glare Factor (AGF) and the Relative Glare Factor (RGF). Literature reviews compared existing luminance thresholds developed by different research groups. More than 450 subjective data and visual scenes have been collected and analyzed to develop a new method. A HDR image analysis tool was developed in MATLAB to calculate luminance values and detect potential glare sources in digitally captured glare scenes. It was determined that using the human eye’s field of view (FOV) improves the discomfort glare evaluation performance. Luminance and glare ratio thresholds were defined in statistical analysis software. In addition to the newly defined luminance and contrast thresholds for different office task types, an AGF- and RGF-based glare equation was developed to evaluate and report perceived glare levels. AGF and RGF dominant zones were displayed on a scatter plot graph to visually explain which glare factor is more dominant to cause discomfort glare. This overall approach can help users to understand a cause of daylight glare and find solutions to avoid glare issues, which would ensure occupant’s visual comfort in buildings.