Thesis (Ph.D.)--University of Nebraska-Lincoln, 2008. / Title from title screen (site viewed Jan. 13, 2009). PDF text: xx, 364 p. : ill. (some col.) ; 6.76 Mb. UMI publication number: AAT 3315315. Includes bibliographical references. Also available in microfilm and microfiche formats.

It has been found that traveling on the roadways at night is an inherently more dangerous task than driving during the daylight hours. Driving is primarily a visual task, and there are certain situations at night in which vision and safety may be compromised. The effects of glare produced by the headlamps of oncoming vehicles have become an interesting problem to many lighting researchers. Depending upon the opposing lighting design (beam distribution and intensity) and the lighting conditions inside the vehicle, oncoming headlamps can be both visually discomforting and disabling to drivers at night. In recent years, the newer High Intensity Discharge (HID) headlamps have raised some concern because of their increased light output and brighter appearance as opposed to traditional Halogen headlamps. The objective of this study was to evaluate the discomfort and disability glare produced by different oncoming headlamps under two driver light adaptation levels. This study took place on the Smart Road at the Virginia Tech Transportation Institute. During the Discomfort Glare portion, participants drove an experimental vehicle at 20mph past the oncoming headlamps and were asked to rate their overall discomfort with the subjective deBoer scale. The Disability Glare portion involved drivers detecting a static pedestrian in the roadway while approaching each different set of glare headlamps. It was hypothesized that there would be significant differences in detection distance and discomfort glare rating across the different glare headlamp and adaptation level combinations. It was also hypothesized that age would have a significant effect on detection distance, and the subjective ratings. The results of this study revealed many significant main effects and interactions for the discomfort and disability glare portions. The main effect of glare source was the only significant factor for discomfort glare. The main effects of age, glare source and pedestrian location were all significant for the disability portion. In addition, the interaction of pedestrian location and glare source was also significant. Overall, there was no clear relationship between subjective discomfort ratings and objective disability measures. The conclusions of this research will be valuable to the consumer as well as the manufacturers and designers of future headlamps in revealing how glare can affect drivers on the road at night. This information can help guide new designs to maximize forward visibility while minimizing glare. / Master of Science

Discomfort glare from daylight is among the most common issues in commercial offices and has been shown to negatively impact productivity, comfort, and well-being. While occupants' adaptive behavioral responses to discomfort glare can significantly alter both the energy use profile and indoor environmental quality of a workspace, little is know about the specific relationship between the environment in which discomfort glare is perceived and the subsequent behavioral response to it. This study proposes a new Glare Response Sensitivity index to evaluate the relationship between environmental parameters and behavioral outcomes in a daylit commercial office building. The results of this study show through a parametric analysis that perceptual sensitivity mediates the relationship between environmental lighting conditions and controls use behaviors. Further, the results suggest that spatial factors including office type and level of control over the environment may affect the likelihood of active lighting controls use behaviors in daylit buildings.

This thesis evaluates the ISO 9241 Part 7, Ergonomic requirements for office work with visual display terminals (VDTs) - Part 7: Requirements for display with reflections. The thesis involved two phases of effort that evaluated the photometric measurements required in the ISO standard in terms of subjective image quality judgments. In phase one, seven monitors were evaluated photometrically according to the ISO 9241-7 standard to determine whether they were Class I, II, or III. Additionally, glare filters were attached to monitors to see if they change the ISO classification of the monitor. The results of phase one indicated that positive polarity always yielded either Class I or Class II because the Large Source, Screen Image Luminance Ratio (LR BDS/FDS) and the Specular Reflection Luminance Ratio (LR BDS/BD) always passed. Conversely, negative polarity always produced Class II or Class III because the Small Source, Specular Reflection Luminance Ratio (LR BDS/BD) failed every time. Also, the AF 150 and HF 300 were the best filters for reducing glare on monitors. The BF 10 and AF 100 or AF 200 ,on the other hand, were the worst because they intensified screen reflections. In phase two, human image quality judgments were collected to determine if people rated Class I, II, or III monitor-filter combinations differently under different lighting and different screen polarity conditions. Specifically, phase two assessed the effects of seven monitor/add-on glare filter combinations, five ambient lighting conditions, and two screen polarities on subjective image quality ratings. Each participant provided subjective image quality judgments by viewing alphanumeric text on the CRT screens. Subjective scale values also were correlated with ISO classifications and two ISO metrics: screen image luminance ratio (Diffuse, 200 lux) and specular reflection image luminance ratio. The ANOVA findings indicated that specular glare significantly degrades image quality ratings more than diffuse glare. The author contends that this finding is the result of an experimental context effect. In other words, the specular glare was so influential on subjective ratings of image quality that subjects paid little or no attention to reductions in contrast from the diffuse lighting conditions. The correlation analysis showed that the specular reflection luminance ratio and the negative polarity classifications did index subjective quality ratings. Finally, this thesis establishes a human factors basis to justify the measurement requirements in the ISO 9241-7 standard. Specifically, the findings show that it underemphasizes the contribution of the specular reflection luminance ratio' and overemphasizes the contribution of the screen image luminance ratio to compliance classification calculations, because the procedure gives equal weight to both ratios. / Master of Science

Purpose: This is a pilot study to investigate gaze strategies for coping with glare when performing a simple visual task under intense contra light viewing conditions. Method: Twenty-four normally sighted participants were recruited for this study. They consisted of a young subgroup (n=12), aged 21-29 (mean = 25.3 ± 2.5), and an older subgroup (n=12), aged 51-71 (mean = 57.3 ± 6.1). Visual acuity (VA) and Brightness Acuity testing (BAT) were used to assess central vision. Participants were required to locate and approach (from 15m) a small platform that was contra lit by a powerful light source. Upon arrival at the platform, participants were required to insert a small ball into a similarly sized receptacle. An ASL Mobile Eye (Bedford, MA) eye tracker was used to monitor gaze position throughout until the task was completed. Scene and pupil videos were recorded for each participant and analyzed frame by frame to locate the participant’s eye movements. Results: Two participants (one from each subgroup) adopted aversion gaze strategies wherein they avoided looking at the contra lit task for more than 50% of the task completion time. For the remainder of the experimental trial, these two participants were either looking toward the glare source or blinking. The other twenty-two participants opted to endure the contra light condition by gazing directly into the glare for the majority of the task completion time. An individual t-test between the younger iv subgroup’s BA scores vs. the older subgroup’s BA scores was statistically significant (p<0.05). Significantly poorer BAT scores were found in the older subgroup, however, individual participant’s BAT scores did not necessarily predict the ability to cope with a contra lit glare source. Although, statistically significant differences were not found between the two subgroups when examining their VA and length of time to complete the course, a trend was found, as the older subgroup consistently had poorer VA scores and took longer to complete the course. Further research must be completed with a larger sample size to fully understand the glare aversion strategies one must elicit when dealing with a contra lit glare source within the built environment, and to confirm the three glare strategies proposed by this pilot study.

Purpose: This is a pilot study to investigate gaze strategies for coping with glare when performing a simple visual task under intense contra light viewing conditions. Method: Twenty-four normally sighted participants were recruited for this study. They consisted of a young subgroup (n=12), aged 21-29 (mean = 25.3 ± 2.5), and an older subgroup (n=12), aged 51-71 (mean = 57.3 ± 6.1). Visual acuity (VA) and Brightness Acuity testing (BAT) were used to assess central vision. Participants were required to locate and approach (from 15m) a small platform that was contra lit by a powerful light source. Upon arrival at the platform, participants were required to insert a small ball into a similarly sized receptacle. An ASL Mobile Eye (Bedford, MA) eye tracker was used to monitor gaze position throughout until the task was completed. Scene and pupil videos were recorded for each participant and analyzed frame by frame to locate the participant’s eye movements. Results: Two participants (one from each subgroup) adopted aversion gaze strategies wherein they avoided looking at the contra lit task for more than 50% of the task completion time. For the remainder of the experimental trial, these two participants were either looking toward the glare source or blinking. The other twenty-two participants opted to endure the contra light condition by gazing directly into the glare for the majority of the task completion time. An individual t-test between the younger iv subgroup’s BA scores vs. the older subgroup’s BA scores was statistically significant (p<0.05). Significantly poorer BAT scores were found in the older subgroup, however, individual participant’s BAT scores did not necessarily predict the ability to cope with a contra lit glare source. Although, statistically significant differences were not found between the two subgroups when examining their VA and length of time to complete the course, a trend was found, as the older subgroup consistently had poorer VA scores and took longer to complete the course. Further research must be completed with a larger sample size to fully understand the glare aversion strategies one must elicit when dealing with a contra lit glare source within the built environment, and to confirm the three glare strategies proposed by this pilot study.

Since the start of the Industrial Revolution there has been a general improvement in working conditions. As part of this process, light in the work place was recognised as an important environmental factor. In the early years of the 20th century it was also recognised that in providing adequate lighting for a particular working environment, there was a need to avoid the potential negative effects of too much, or inappropriately distributed, light. One of the negative effects of light in the work place was glare. Holladay (Holladay, (1926)) attributed the negative effects of glare to impairment of vision caused by light scatter. Stiles (Stiles, (1929)) refuted Holladay's case by arguing that only a small proportion of the reduction in task visibility could be attributed to light scatter effects (where task visibility is a measure of how far above the visual threshold a task's contrast is). Stiles distinguished disability glare, a light scatter effect, from discomfort glare which was glare that could not be attributed to light scatter. The distinction made by Stiles resulted in the separate development of discomfort and disability glare models. Very few, if any, studies since Stiles have re-evaluated the potential association between subjectively rated discomfort glare, and physically based disability glare. In the study reported here, subjects were asked to set the appearance of a 2° glare source so that it appeared at the Borderline between Comfort and Discomfort, or BCD (Guth, (1963)). Each subject's visual threshold for a 4 cycle per degree spatial grating was measured under BCD and control conditions, and a comparison made to assess if light scatter effects from the glare source influenced threshold contrast, C_th. The results of the study indicate that C_th, can be lower in the presence of the glare source set to BCD. This anomaly may be explained by improvement in image quality caused by the glare source driving the pupil to a smaller diameter. More significantly, there was found to be a strong correlation between subjective BCD settings and age, and also between BCD settings and control condition C_th. Both of these results suggest an influence of light scatter on BCD settings of discomfort glare. This conclusion was further supported by the fitting to the data of the independently reported stray light function of Ijspeert et al (Ijspeert et al, (1990)). Thus the results strongly suggest a correlation between subjective BCD settings of a glare source and light scatter function. A conclusion that substantially weakens Stiles' argument that discomfort glare is not dependent on light scatter effects. Using the results of the study, a new threshold type model for assessing discomfort glare is proposed, which explicitly includes age as a parameter. However, much variance remains to be explained in the glare data. Therefore, a second theme investigated in the dissertation is the possible association between scene visual structure and visual discomfort. The results of this study indicate that there is a small but significant difference in the image structure of natural and man made environments. This difference may contribute to visual discomfort, but will require further investigation.

This research effort focused on ascertaining the headlamp technology (of the eleven specified) that minimized the amount of discomfort glare and maximized the visibility of three types of pavement marking materials used in the study. Two baseline conditions, halogen low beam (HLB) and high-intensity discharge (HID) were measured both individually and in combination with three levels of UV-A. In addition, three other headlamp configurations were evaluated. Discomfort glare was measured subjectively for each headlamp configuration. Pavement marking visibility was directly measured via pavement marking detection distances. Thirty participants representing three age groups participated in this study: young (18-25 years old), middle (40-50 years old), and older (60 years and older). The headlamp technology and the pavement marking material needed to be beneficial for all age groups as all would potentially use the new technology if it were implemented in vehicles and roadways in the future. Participants evaluated discomfort glare at both a far and close distance using the nine-point DeBoer scale and evaluated pavement marking visibility by indicating when they could see the first and last pavement markings in each of the three sections. Overall, it was found that the HID configurations (HID, Middle UV-A + HID, High UV-A + HID) with a sharp cut-off beam pattern provided the least amount of discomfort glare. In contrast, the halogen configurations (HLB, Hybrid UV-A + HLB, Middle UV-A + HLB, High UV-A + HLB) and high output halogen with a straight-ahead beam pattern provided the longest detection distances. Two of the pavement markings: a two part liquid system (developed by 3M) and a fluorescent paint provided longer detection distances than a thermoplastic marking. / Master of Science

O presente trabalho é um estudo qualitativo do comportamento mecânico do laminado metal-fibra GLARE-5 2/1, submetido a impacto balístico subsônico em condições que simulam à amplitude térmica em aplicações espaciais. Para isto, os corpos de prova foram submetidos e ao impacto balístico de um projétil cilíndrico e alguns destes foram submetidos ao choque térmico, alternando entre -196 e 100°C. Os danos causados por estes ensaios foram analisados com as técnicas de microscopia óptica e tomografia computadorizada de raios X (X-Ray CT), que permitiram o entendimento dos danos em duas e três dimensões. Comparouse o resultado entre estas técnicas e a influência do ordenamento das amostras no escaneamento deste material. Concluiu-se que a X-Ray CT é uma técnica não destrutiva que proporciona boa informação para o entendimento dos danos internos causados pelo impacto no GLARE, embora não replicou com exatidão os danos observados na microscopia óptica. Além disso, o agrupamento de amostras do GLARE para o escaneamento permitiu melhorar a qualidade das imagens resultantes destes escaneamentos. Os danos mais comuns causados pelo impacto foram delaminações metal-fibra, trincamentos na matriz polimérica e delaminações fibra-fibra, sendo a condição criogênica a que resultou em maior volume de danos. Amostras submetidas ao choque térmico mostraram uma queda de sua temperatura de transição vítrea e ganho na resistência ao impacto. / This is a qualitative study of the mechanical behavior of the metal-fiber laminate GLARE-5 2/1 subjected to subsonic ballistic impact under conditions that simulate thermal amplitude in space applications. For this, the specimens were submitted to the ballistic impact of a cylindrical projectile; some specimens were previously thermal shocked, alternating between - 196 and 100 ° C. The damages caused by these tests were analyzed by optical microscopy and X-ray CT (X-Ray CT), which allows the understanding of damage in two and three dimensions. Were compared the results between these techniques and the influence of the ordering of the samples in the scanning of this material. It was concluded that X-Ray CT is a non-destructive technique that provides good information for understanding the internal damage caused by impact on GLARE, although it did not replicate accurately the damage observed under light microscopy. In addition, GLARE sample collation for scanning has improved the quality of the images resulting from these scans. The most common damages caused by the impact were metal-fiber delamination, cracking in the polymer matrix and fiber-fiber delamination, the cryogenic condition being the result of greater damage. Samples subjected to thermal shock showed a drop in their glass transition temperature and gain in impact resistance.

Veiling glare has always existed in cars, but during the last years it has been brought up as a big problem. One reason is that glossier materials are being used in car interior design. Another reason is that the customers who buy the cars are getting more quality conscious. They demand to get top quality for the high price that they pay for a car, and veiling glare problems could be regarded as “low quality”. Veiling glare is when light hits the car interior and reflects into the windshield, causing mirror-like images in the windshield (ghost images). This can impair the driving experience in two ways. It can lower the contrast of the road scene and it may be a cluttering for the driver. This work handles daytime veiling glare from dashboard reflectance. The purpose was to investigate the area and to see if Saab can avoid the problem with veiling glare by using virtual prototyping (see chapter 3.3.1). This has been done by examining if the light simulation software Speos can be used to simulate and predict veiling glare, and thereby be used as a tool for better design. Key words: Veiling glare, dashboard, windshield, Speos, virtual prototyping.