Levels Of Glare Research Articles

The role of fenestration in promoting daylight performance. The mosques of Alexandria since the 19th century

Mosques have always been sacred places with distinctive sustainable environments. Fenestration in the prayers’ zone whether clerestories, screened windows, dome lighting and other light features have managed to produce significant spiritual human comfort areas. This paper focuses on fenestration of divine mosques and relates them to promoting daylight performance. The research process emphasizes the importance of daylight performance by promoting simulation tools on historical mosques of Alexandria since the 19th century that has witnessed change over time. The paper is a step toward sustainable lighting schemes in prayers’ zones that help to achieve human comfort as well as minimize use of energy. This study aimed at investigating the daylight performance by the use of climate based daylighting metrics which is “Daylight Autonomy” (DA). Daylight Autonomy is evaluated in the year round for the day lighted prayer periods to evaluate the behavior of fenestration of the different selected sample of mosques since the 19th century in Alexandria on a simulation tool in order to check whether it complies with the required illuminate and glare levels. The research findings are an attempt to lead to performative design guidelines introducing a contemporary interpretation for use in enhancing new designs of these holistic buildings.

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.

Test track evaluation of headlight glare associated with adaptive curve HID, fixed HID, and fixed halogen low beam headlights

Adaptive curve headlights swivel with steering input and are linked to reduced insurance claims and improved visual performance. This study assessed glare experienced from adaptive curve high-intensity discharge (HID), fixed (non-swiveling) HID and fixed halogen headlights – all tested in low beam mode. Twenty participants rated glare from vehicles’ headlights using the DeBoer visual discomfort scale as a test driver drove towards them from five approaches on a test track. Participants rated the fixed halogen condition as less glaring than the adaptive curve and fixed HID conditions. There was no significant difference in ratings between the HID low-beam conditions. Collapsing across roadway approaches, the mean subjective ratings for the fixed halogen, adaptive curve HID and fixed HID low-beam conditions indicated ‘satisfactory’ levels of glare. Differences between subjective ratings were supported by illuminance data. Differences among the three low-beam systems appear minor, relative to their differences from a benchmark high-beam condition.Practitioner Summary: Insurance data indicates reduced claims associated with adaptive curve lighting. The current effort was to study how such lighting affects discomfort glare of oncoming drivers relative to conventional headlights. Participants rated halogen headlights as less glaring than fixed and adaptive curve HID low beams. Differences among systems were small and associated with acceptable levels of discomfort glare.

Google Glass Glare: disability glare produced by a head-mounted visual display.

Head mounted displays are a type of wearable technology - a market that is projected to expand rapidly over the coming years. Probably the most well known example is the device Google Glass (or 'Glass'). Here we investigate the extent to which the device display can interfere with normal visual function by producing monocular disability glare. Contrast sensitivity was measured in two normally sighted participants, 32 and 52 years of age. Data were recorded for the right eye, the left eye and then again in a binocular condition. Measurements were taken both with and without the Glass in place, across a range of stimulus luminance levels using a two-alternative forced-choice methodology. The device produced a significant reduction in contrast sensitivity in the right eye (>0.5 log units). The level of disability glare increased as stimulus luminance was reduced in a manner consistent with intraocular light scatter, resulting in a veiling retinal illuminance. Sensitivity in the left eye was unaffected. A significant reduction in binocular contrast sensitivity occurred at lower luminance levels due to a loss of binocular summation, although binocular sensitivity was not found to fall below the sensitivity of the better monocular level (binocular inhibition). Head mounted displays such as Google Glass have the potential to cause significant disability glare in the eye exposed to the visual display, particularly under conditions of low luminance. They can also cause a more modest binocular reduction in sensitivity by eliminating the benefits of binocular summation.

An assessment of the effectiveness of high definition cameras as remote monitoring tools for dolphin ecology studies.

Research involving marine mammals often requires costly field programs. This paper assessed whether the benefits of using cameras outweighs the implications of having personnel performing marine mammal detection in the field. The efficacy of video and still cameras to detect Indo-Pacific bottlenose dolphins (Tursiops aduncus) in the Fremantle Harbour (Western Australia) was evaluated, with consideration on how environmental conditions affect detectability. The cameras were set on a tower in the Fremantle Port channel and videos were perused at 1.75 times the normal speed. Images from the cameras were used to estimate position of dolphins at the water’s surface. Dolphin detections ranged from 5.6 m to 463.3 m for the video camera, and from 10.8 m to 347.8 m for the still camera. Detection range showed to be satisfactory when compared to distances at which dolphins would be detected by field observers. The relative effect of environmental conditions on detectability was considered by fitting a Generalised Estimation Equations (GEEs) model with Beaufort, level of glare and their interactions as predictors and a temporal auto-correlation structure. The best fit model indicated level of glare had an effect, with more intense periods of glare corresponding to lower occurrences of observed dolphins. However this effect was not large (-0.264) and the parameter estimate was associated with a large standard error (0.113). The limited field of view was the main restraint in that cameras can be only applied to detections of animals observed rather than counts of individuals. However, the use of cameras was effective for long term monitoring of occurrence of dolphins, outweighing the costs and reducing the health and safety risks to field personal. This study showed that cameras could be effectively implemented onshore for research such as studying changes in habitat use in response to development and construction activities.

Optical functional performance of the osteo-odonto-keratoprosthesis.

The aim of this study was to evaluate optical and visual functional performance of the osteo-odonto-keratoprosthesis (OOKP). Optical design and analysis was performed with customized optical design software. Nine patients with implanted OOKP devices and 9 age-matched control patients were assessed. Contrast sensitivity was assessed and glare effect was measured with a brightness acuity test. All OOKP patients underwent kinetic Goldmann perimetry and wavefront aberrometry and completed the National Eye Institute Visual Function Questionnaire-25 (NEI VFQ-25). Optical analysis showed that the optical cylinder is near diffraction-limited. A reduction in median visual acuity (VA) with increasing glare settings was observed from 0.04 logMAR (without glare) to 0.20 logMAR (with glare at "high" setting) and significantly reduced statistically when compared with the control group at all levels of glare (P < 0.05). Contrast sensitivity was significantly reduced when compared with age-matched controls at medium and high spatial frequencies (P < 0.05). Median Goldmann perimetry was 65 degrees (interquartile range, 64-74 degrees; V-4e isopters) and 69 degrees excluding 2 glaucomatous subjects. Several vision-related NEI VFQ-25 subscales correlated significantly with VA at various brightness acuity test levels and contrast sensitivity at medium spatial frequencies, including dependency, general vision, near activities and distance activities. The OOKP optical cylinder provides patients with a good level of VA that is significantly reduced by glare. We have shown in vivo that updates to the optical cylinder design have improved the patient's field of view. Reduction of glare and refinement of cylinder alignment methods may further improve visual function and patient satisfaction.

Glare effect for three types of street lamps based on White LEDs

This study is aimed to assess the glare effect from LED-based street lamps with three general optical designs, which are cluster LEDs with a single lens, a LED array accompany with a lens array, and a tilted LED array, respectively. Observation conditions were simulated based on various locations and viewing axes. Equivalent luminance calculations were used to reveal the glare levels of the three designs. The age effect for the calculated equivalent luminance was also examined for human eyes of people at the age of 40 or 60. The results demonstrate that among the three design types, a LED array accompany with a lens array causes relatively smaller glare for most viewing conditions.

A new approach in the design of electronic portal imaging devices for portal dosimetry in radiotherapy

A CCD-based EPID using new crystal-assembly X-ray (CAX) converters is investigated for radiotherapy dosimetry. The proposed EPID design consists in replacing the common phosphor X-ray converters of current CCD-based EPIDs with high-stopping-power CAX converters. A Test Imaging Device (TID), consisting of a 30-mm-thick CAX converter made of Bismuth Germanate (BGO), coupled to a highly sensitive CCD camera, was used to evaluate the accessible imaging and dosimetric performance of the proposed design. The system response to dose and its dependence on photon beam energy were investigated. The effects of ghosting, dose rate, field size and phantom thickness were evaluated as well. The same measurements were also performed with our clinically used aSi-EPID so that comparisons of performance could be directly inferred. The TID displayed no detectable ghosting or sensitivity to dose rate. Its response to MU exposure was found to be linear within about ±1%. The level of glare induced in the TID and the aSi-EPID were equivalent. The TID resolution was higher than that of the aSi-EPID on the axis, but was found to decrease with off-axis distance. Finally, the image quality, assessed on the basis of signal-to-noise ratio in low dose radiographs of the larynx of a patient, was higher for the TID. The imaging performance accessible with the TID proved to be satisfying and its dosimetric capability was found to be superior to that of the current aSi-EPID.

Disability glare: A study in simulated road lighting conditions

Disability glare is associated with veiling luminance caused by light from bright sources being scattered within the eyes of observers, thereby reducing retinal luminance contrast. This study compares the reduction in observers’ performance in the presence of glare with veiling luminance in the eye, calculated using a non-subjective method. A total of 42 observers performed a target detection task in the presence of a glare source in conditions similar to street lighting at night. Luminance contrast thresholds were measured for each observer under different levels of glare. Results show that, while veiling luminance has a significant effect on the performance of observers, its effect is lower than expected from contrast loss. Furthermore, the performance of observers over the age of 50 is unaffected by increasing the glare level.

Empirical Assessment of a Prismatic Daylight-Redirecting Window Film in a Full-Scale Office Testbed

ABSTRACTDaylight-redirecting systems with vertical windows have the potential to offset lighting energy use in deep perimeter zones. Microstructured prismatic window films can be manufactured using low-cost, roll-to-roll fabrication methods and adhered to the inside surface of existing windows as a retrofit measure or installed as a replacement insulating glass unit in the clerestory portion of the window wall. A clear film patterned with linear, 50- to 250-μm-high, four-sided asymmetrical prisms was fabricated and installed in the south-facing, clerestory low-e, clear glazed windows of a full-scale testbed facility. Views through the film were distorted. The film was evaluated in a sunny climate over a 2-year period to gauge daylighting and visual comfort performance. The daylighting aperture was small (window-to-wall ratio of 0.18) and the lower windows were blocked off to isolate the evaluation to the window film. Workplane illuminance measurements were made in the 4.6-m (15-ft)-deep room furnished as a private office. Analysis of discomfort glare was conducted using high dynamic range imaging coupled with the EvalGlare software tool, which computes the daylight glare probability and other metrics used to evaluate visual discomfort.The window film was found to result in perceptible levels of discomfort glare on clear sunny days from the most conservative view point in the rear of the room looking toward the window. Daylight illuminance levels at the rear of the room were significantly increased above the reference window condition, which was defined as the same glazed clerestory window but with an interior Venetian blind (slat angle set to the cut-off angle), for the equinox to winter solstice period on clear sunny days. For partly cloudy and overcast sky conditions, daylight levels were improved slightly. To reduce glare, the daylighting film was coupled with a diffusing film in an insulating glazing unit. The diffusing film retained the directionality of the redirected light spreading it within a small range of outgoing angles. This solution was found to reduce glare to imperceptible levels while retaining for the most part the illuminance levels achieved solely by the daylighting film.

China's Streets Lighting Environment Impact Factors Analysis

This paper proposed a new method of describing street glare. Glare is a typical light environment, it is affected by streetlights and street surface conditions. It impact on street safety. This paper based on survey of Tianjin, Changsha, Zhengzhou street area, included optical lights types, height of light bulbs, distance between tow lights, street surface brightness, illumination and other factors examination and record. Survey date had been used to set 36 street lighting simulated models and compare with the calculation. The output for the analysis is a series of maps reflecting the relationship between street glare environment and its factors. The case study proved that street lighting environment is closely associated with streetlights bulbs brightness and its installation site. The results show that high level of light brightness will lead to high level of glare and higher light bulbs will increase glare.

Visual comfort assessment of smart photovoltachromic windows

An experimental study of photovoltachromic (PVCC) devices for dynamic solar control in buildings is presented. The fabricated devices underwent a complete opto-eletctrical characterization and the results obtained were employed as an input for the simulation of building integrated multifunctional windows. This multidisciplinary activity aims at achieving relevant feedbacks from the simulation of real large area devices in order to adjust and even direct further experimental efforts, before reaching the production phase. Devices having different electrochromic capacitances were used and the optical measurements became useful inputs for the simulation task. Simulation's results turned into feedbacks concerning the modulation of the transmittance spectra, the colour of bleached devices, the scale-up of PVCCs. Devices used in the current work showed a power peak of 4.22mW/cm2 at the maximum power point and a smart modulation of optical transmittance of 50.16% (at 700nm). Simulations of natural light penetration in office buildings showed that the integration of PVCCs in traditional windows could dramatically increase indoor visual comfort. An increase of the average UDI for a typical room up to 71.8% and a decrease of intolerable glare levels (DGP higher than 0.45) down to 12% were the major benefits of the substitution of traditional clear glasses with integrated PVCCs.

Retinal mesopic adaptation model for brightness perception under transient glare

A glare source in the visual field modifies the brightness of a test patch surrounded by a mesopic background. In this study, we investigated the effect of two levels of transient glare on brightness perception for several combinations of mesopic reference test luminances (Lts) and background luminances (Lbs). While brightness perception was affected by Lb, there were no appreciable effects for changes in the Lt. The highest brightness reduction was found for Lbs in the low mesopic range. Considering the main proposal that brightness can be inferred from contrast and the Lb sets the mesopic luminance adaptation, we hypothesized that contrast gain and retinal adaptation mechanisms would act when a transient glare source was present in the visual field. A physiology-based model that adequately fitted the present and previous results was developed.

Work Zone Lighting and Visual Performance

In part because of the potential for high levels of glare from work zone illumination, recommendations for light levels from work zone illumination systems are substantially higher than for levels used along roadways in non–work zone locations. In a two-part study, requirements for work zone illumination light levels were assessed. First, levels for workers varying in age from 20 to 60 years were evaluated with the relative visual performance model, with and without the presence of visibility-reducing glare. Except for the smallest, lowest-contrast tasks performed by the older workers, an illuminance of 10 lx resulted in visibility well above the threshold even in the presence of glare, and an illuminance of 30 lx resulted in suprathreshold visibility for these conditions as well. The results of these computational analyses were largely confirmed in a full-scale, outdoor field demonstration attended by transportation agency engineers and highway contractors. Together, the findings suggest that when lighting systems provide sufficient glare control, light levels do not always need to be especially high to ensure adequate visibility for workers.

Investigation of Evalglare software, daylight glare probability and high dynamic range imaging for daylight glare analysis

The latest glare metric, called daylight glare probability (DGP), has been developed specifically for daylight glare issues inside a building. Unlike other glare indices, DGP considers vertical illuminance values at the human eye when evaluating different levels of discomfort glare. One of the options to calculate DGP is to use a high dynamic range imaging (HDRI) technique and Evalglare glare analysis software. This paper briefly shows USC Watt Hall 3rd floor interior glare study results and explains the inconsistent glare evaluations from different glare indices. Then, an additional study thoroughly investigates Evalglare algorithms and HDR image capturing procedures. Pathological cases were set up inside the office on USC Watt Hall 3rd floor and tested to see if the results are as predicted by the algorithms.

Susceptibility to pattern glare following stroke

The aim of this work was to measure susceptibility to pattern glare within a stroke group, employing a direct method of assessment. Twenty stroke subjects, aged 38–85 years, were recruited, along with an age-matched control group (n = 20). Assessment of pattern glare susceptibility was undertaken using the pattern glare test. An abnormal degree of pattern glare is present when individuals score >1 on the mid-high spatial frequency difference variable, a relative score that allows for normalization of the subject, or >3 when viewing the mid spatial frequency grating. Stroke subjects demonstrate elevated levels of pattern glare compared to normative data values and a control population, as determined using the pattern glare test. This was most notable when considering the output measure for the mid-high difference variable. The mean score for the mid-high difference variable was 2.15 SD 1.27 for the stroke subjects versus 0.10 SD 1.12 for the control subjects. When considering the mid-high difference variable, 75% of the stroke group recorded an abnormal level of pattern glare compared to 5% in the control group. This study demonstrates an association between stroke subjects and elevated levels of pattern glare. Cortical hyperexcitability has been shown to present following stroke, and this has been proposed as a plausible explanation for the perceptual distortions experienced by individuals susceptible to pattern glare. Further work to assess the benefits of spectral filters in reducing perceptual distortions in stroke patients is currently underway.

Effects of screen filter on visibility of alphanumeric presentation on CRT and LCD monitors

In this paper, a research that deals with the problem of determining of the visibility of the alphanumeric presentation on CRT and LCD screens is presented, in conditions when the screen filters are used, and when they are not used. A methodology that can be used for determination of the visibility of alphanumeric symbols on VDT screens is presented. It is determined the existence of differences in visibility of alphanumeric presentations when screen filters are used, compared to conditions when they are not used. This difference was statistically significant, while the visibility of the presented alphanumeric symbols on CRT and LCD screens that use screen filters is lower than when they are not used. For this reason, the use of protective screen filter is recommended in circumstances where a very high level of glare exists, when the visual fatigue is common appearance and when a user performs a task that does not depend on the detection of stimuli whose RGB values are low.

Energy Saving Through the Sun: Analysis of Visual Comfort and Energy Consumption in Office Space

Energy demands for heating, cooling and lighting can be dramatically prejudiced by the façade configuration, solar exposition and typology of openings trying to maximize use of natural light. Office buildings are often field of experimentation of materials and innovative components, by the way a consolidated design market promotes façade layouts strongly transparent introducing a primary need to shading and protection of the users privacy. Building Automation Systems (BAS) can reduce users’ intervention on indoor condition control; on the other hand users want to be capable to fix conditions in their working space avoiding problems of visual discomfort, specifically disturbing and intolerable levels of glare. Systems to evaluate visual comfort parameters to improve consciousness in use of daylighting are fundamental in design to realize a façade which permits real energy saving during operation time.The present study aims to analyze a single office space with three differe nt configuration of the openings located in different orientation and position (south exposed window, north exposed window and skylight). The three cases study are evaluated on optimization of natural lighting, visual comfort, electricity consumption and h eating and cooling demand and consumption. To perform these kind of calculation with the correct level of detail is crucial to make use of a appropriate tools which can estimate the value of the different parameters to assess energy and visual quality of the indoor space. It is not possible to use just one tool to collect all the information required to optimize a building in order to obtain a NZEB level of consumption. The high standards required by the new regulations need a full -range analysis and a specific knowledge of all the parameters involved. In this study are used six software for the simulation of the all needed parameters (Ecotect, Radiance, Evalglare, Daysim, Dialux, Open Studio).

Evaluation of Visual Performance Using LED Signboards under Different Ambient Conditions

This research aimed to study how to make the light emitting diode (LED) signboards be more legible under high illuminative conditions and to avoid the observers feeling dazzling glare under low illuminative conditions. This research firstly studied the literatures to explore the drivers’ visual ergonomic as well as the optical properties of LED, and investigated the relatively existing norms for engineering vehicle LED signboards. Three variables were set in this study: three kinds of ambient condition, four kinds of luminance contrast and two kinds of character form. In the first phase of the experiment, subjects observed LED signboards in both near and distant locations and filled out the SWN scale (Subjective Well-being under Neuroleptics), and in the second phase, subjects were then asked to moved forward and recorded their perceptions of comfort and glare to distance range. The findings demonstrated that, there was no variation in subjective evaluation to display signs with no backgrounds either in the near or distant locations, while to display signs with backgrounds, the subjects perceptions were the farther the distance, the clearer the legibility; higher ambient illumination could effectively reduce observers’ glare perception to LED signboards; signboards with backgrounds at the luminance contrast of 3:1 (L max=3100, L min=1033cd / m2) showed the lowest uncomfortable and glare level to observers. The two forms of character showed no significant variation in affecting observers in terms of the comfort and glare perception.

Effect of glare on reaction time for peripheral vision at mesopic adaptation

When a bright light is present in the field of view, visibility is dramatically reduced. Many studies have investigated the effect of glare on visibility considering foveal vision. However, the effects on peripheral vision have received little attention. In a previous work [J. Opt. Soc. Am. A 25, 1790 (2008)], we showed that the effect of glare on reaction time (RT) for foveal vision at mesopic adaptation depends on the stimulus spatial frequency. In this work, we extend this study to peripheral vision. We measured the RT of achromatic sinusoidal gratings as a function of contrast for a range of spatial frequency, and eccentricity, and for two glare levels, in addition to the no-glare condition. Data were fitted with Piéron's law, following a linear relationship. We found that glare increases the slope of these lines for all conditions. These slopes seem to depend critically on eccentricity for 4 cycles/degree (c/deg), but not for 1 and 2 c/deg. We explain our results in terms of the contrast sensitivity (gain) of the underlying detection mechanisms.