Headlight Glare Research Articles

Monocular thermal imaging for pedestrian detection and ranging

To react to the presence of pedestrians, an automated braking system must first find the pedestrian(s) including locations relative to the automobile both in angular position and in distance. In the daytime, cameras and radar can provide the necessary information, but this combination, which requires ambient or active illumination, fails at night. Passive thermal sensors are now being enlisted to dramatically improve imaging at night, whereas substantial effort is underway to assure proper fusing of object information from the thermal sensor with other sensors on the automobile. To simplify the acquisition of information needed to make valid automated braking decisions at night, a camera system with a thermal image sensor was developed that identifies pedestrians and labels each identified pedestrian with location and distance data. The camera utilizes a single uncooled custom microbolometer sensor and a software suite implementing artificial intelligence and machine learning capabilities, running on a combination of convolutional neural networks and fusion processing to provide the data that an automobile host computer needs to implement fast, safe, and accurate automatic braking. We present details of the system construction and operation as well as initial test results showing the potential this technology has to dramatically reduce pedestrian fatalities at night as well as augment safety across all conditions, whether day, night, fog, rain, snow, dust, sun glare, or headlight glare.

Study on the Influence of Opposing Glare from Vehicle High-Beam Headlights Based on Drivers’ Visual Requirements

The anti-glare facilities in median strips are designed to block opposing headlights in order to avoid disability glare, but a large amount of headlight leakage results in uncomfortable glare, to the point that drivers can barely detect dangerous obstacles or road conditions. This paper aims to explore the glare range under high-beam headlights on drivers’ visual requirements. Based on an analysis of the mechanism of headlight glare, this paper proposes a subjective headlight glare scale, and classifies glare discomfort into two categories: interference glare, and acceptability glare. Combining the scales, 24 drivers and a standard light-emitting diode automotive headlamp were used to conduct glare effect tests. The size of the laboratory that closes to scotopic vision is 12 m × 6 m. The illuminance thresholds of disability glare–interference glare (DGIG) and interference glare–acceptability glare (IGAG), along with the spatial distribution of each glare level, were collected at the longitudinal distances of 3 m, 5 m, 7 m, 10 m, and 12 m. Meanwhile, the illuminance threshold and the spatial distribution of each glare level up to a longitudinal distance of 120 m were calculated. The results indicate that disability glare is distributed in the central area, while interference glare and acceptability glare are distributed from the center to the margins. At the same longitudinal distance, the vertical illuminance of the driver’s eye under the same glare level is almost equal. In the range of a longitudinal distance of 120 m, the spatial distribution of each glare level enlarges with each increase in longitudinal distance. The results can provide scientific evidence for calculating the reasonable heights of anti-glare facilities for expressways with different alignments.

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Deep Visible and Thermal Camera-based Optimal Semantic Segmentation using Semantic Forecasting

Abstract Visible camera-based semantic segmentation and semantic forecasting are important perception tasks in autonomous driving. In semantic segmentation, the current frame's pixel level labels are estimated using the current visible frame. In semantic forecasting, the future frame's pixel-level labels are predicted using the current and the past visible frames and pixel-level labels. While reporting state-of-the-art accuracy, both of these tasks are limited by the visible camera's susceptibility to varying illumination, adverse weather conditions, sunlight and headlight glare etc. In this work, we propose to address these limitations using the deep sensor fusion of the visible and the thermal camera. The proposed sensor fusion framework performs both semantic forecasting as well as an optimal semantic segmentation within a multi-step iterative framework. In the first or forecasting step, the framework predicts the semantic map for the next frame. The predicted semantic map is updated in the second step, when the next visible and thermal frame is observed. The updated semantic map is considered as the optimal semantic map for the given visible-thermal frame. The semantic map forecasting and updating are iteratively performed over time. The estimated semantic maps contain the pedestrian behavior, the free space and the pedestrian crossing labels. The pedestrian behavior is categorized based on their spatial, motion and dynamic orientation information. The proposed framework is validated using the public KAIST dataset. A detailed comparative analysis and ablation study is performed using pixel-level classification and IOU error metrics. The results show that the proposed framework can not only accurately forecast the semantic segmentation map but also accurately update them.

Real-time automotive night-vision system for drivers to inhibit headlight glare of the oncoming vehicles and enhance road visibility

The vision problem of drivers during the night is mainly owing to the high-intensity headlight-beam of the oncoming vehicle from the reverse direction. It causes temporary blindness to the driver. To overcome this situation, people generally use color windshield glass, sun visor, and night-vision glass. But, these are not considered as the best solution since it decreases the light intensity of the entire view including the road. Many researchers used various image enhancement techniques to overcome this situation. But, the existing approaches are unable to dim the high-beam headlights of oncoming vehicles without affecting the road view. In this paper, a novel night-vision system is proposed to resolve the problem in real-time for manual-driving vehicles and autonomous vehicles. The proposed method includes region segmentation of frames, local enhancement techniques in different regions followed by adaptive Gaussian filtering. Pixels masking, gamma correction, and low-light pixel enhancement are applied to three distinct regions. Both autonomous vehicles and manual drivers can get a bright and a prominent view of the road with dim headlights of oncoming vehicles in real-time. Numerous heuristic real-time test reveals the performance superiority of the projected system compared to state-of-art methods in quantitative as well as qualitative point of view.

Resin-impregnated wooden anti-glare board and its outstanding exterior performance

A large amount of plant waste from the sides of highways is trimmed and burned, which causes environmental pollution. In addition, headlight glare that occurs when two cars pass each other is dangerous. Traditional anti-glare boards are mostly made of metal, plastic, and other materials that easily age and are expensive to recycle. To recycle the plant waste and prevent glare-related accidents, in the present study, a painted wooden anti-glare board (WAB) was developed and its performance was investigated. In the WAB, there are 7 layers of eucalyptus veneers interlaced, and the mechanical strength of the board prepared with a gradient hot-pressing process after impregnation with phenolic resin was good (79.8 MPa). The wind load resistance of the WAB reached 864 N, which meets GB/T 24718 (2009) and is close to that of glass fiber-reinforced plastic anti-glare boards (914 N). After 10 cycles of weather resistance tests comprising submersion, freezing, and hot-drying, the average static bending strength of the WAB was 29.6 N/mm2. The limited oxygen index of the WAB was 26.1%. Therefore, the WAB showed good properties. The implemented research strategy broadens the application range of the wood composite material and endows it with high added value.

Driver glare exposure with different vehicle frontlighting systems

Introduction: Highway safety performance at night has received less attention in research than daytime, despite the higher accident rates occurring under night-time conditions. This study presents a procedure to assess the potential hazard for drivers created by headlight glare and its interaction with the geometric design of highways. Method: The proposed procedure consists of a line-of-sight analysis performed by a geoprocessing model in geographic information systems to determine whether the rays of light that connect headlights and oncoming drivers are obstructed by either the roadway or its roadsides. Then, the procedure checks whether the non-obstructed rays of light are enclosed by a given headlight beam. Different hypotheses were set concerning the headlight beam features, including the horizontal spread angle and whether the headlights are fixed or swiveling. A highway section was selected to test and validate the procedure proposed. A 3D recreation of the highway and its environment derived from a LiDAR point cloud was used for this purpose. Results: The findings disclose how glare is produced on tangents, horizontal curves, transitions between them and sequences of curves. The effect of visual obstructions conveniently placed is also discussed. Conclusions: A greater glare incidence is produced as the horizontal headlights spread angle increases. Swiveling headlights increase glare on highways left curves and reduce it on right curves. Practical Applications: The procedure and conclusions of this study can contribute to develop more effective glare avoidance technologies as well as identify and assess glare-prone sections. The glare evaluation assists in evaluating glare countermeasures such as deciding whether to place a vegetation barrier and where.

Validation of the driver ecological glare test

IntroductionThe present study proposes to validate the Driver Ecological Glare Test (DEGT), a test developed to measure the benefit of a headlight glare Advanced Driver Assistance System (ADAS), by comparing it to a laboratory glare test. Method: Twenty-four participants, aged from 55 to 70 years, were recruited to complete a visual examination, including monocular halo size measurement for both eyes using Vision Monitor device (MonCv3; Metrovision). An on-field evaluation took place at night at the UTAC CERAM test track to obtain disability glare measures using the DEGT. Results: A significant correlation was found between the two glare tests and Bland-Altman analysis reveals a good agreement with a bias of 73.7 arcmin between the halo size measurements obtained from the DEGT and Vision Monitor. The results of the present study demonstrate that the DEGT is a valid method to test halo size and is adapted to evaluate the benefits of an antiglare device for drivers in an ecological situation.

Effect of central hole location in phakic intraocular lenses on visual function under progressive headlight glare sources

To analyze the effect of the central hole location in the V4c implantable collamer lens (ICL) on the quality of vision, including progressive headlight glare simulation and quality of life. IOBA-Eye Institute, Valladolid, Spain. Case series. The central hole location was determined by slitlamp and dual Scheimpflug imaging for 6months or more postoperatively. The visual acuity, mesopic contrast sensitivity, halogen glare contrast sensitivity, xenon glare contrast sensitivity, photostress recovery time after glare, de Boer scale, and Quality of Life Impact of Refractive Correction (QIRC) questionnaire results were evaluated. Multiple regression models were used to analyze the effect of the central hole location on parameters using the pupil center and visual axis as references based on Cartesian and polar coordinates. The safety index was 1.13 and the efficacy index, 1.12. Under all testing circumstances, central hole decentration did not affect the visual acuity or contrast sensitivity. With the visual axis as a reference, worse QIRC values were associated with greater upward central hole displacement (P=.03) and a lower polar angle value (P=.008); also, halogen glare discomfort was greater with a higher radius (P=.04). Using the pupil center as a reference, greater nasal central hole decentration was associated with longer xenon glare photostress recovery time (P=.002). Implantation of the ICL with a central hole yielded excellent visual outcomes, even under increasing glare sources, regardless of the hole's location. However, hole decentration might affect patient-perceived quality of life, bothersome halogen glare, and longer xenon glare photostress recovery time. Such complaints after the early postoperative period might be managed with discrete ICL centration if the central hole is decentered upward or nasally.

Comparison of Pedestrian Detection With and Without Yellow-Lens Glasses During Simulated Night Driving With and Without Headlight Glare

Some marketing materials for yellow-lens night-driving glasses claim that they increase nighttime road visibility and reduce oncoming headlight glare (HLG). However, there is no scientific evidence to support these claims. To measure the association between yellow-lens glasses and the detection of pedestrians with and without an oncoming HLG, using a driving simulator equipped with a custom HLG simulator. A single-center cohort study was conducted between September 8, 2016, and October 25, 2017, at the Schepens Eye Research Institute. A total of 22 individuals participated in the study, divided into groups to determine response to a pedestrian wearing a navy blue shirt by younger individuals and, to control for participant's age and the interaction of the shirt color with the filter, response to a pedestrian wearing an orange shirt by a group of younger and older participants. Participants drove scripted night-driving scenarios, 3 times with 3 commercially available yellow-lens glasses and once with clear-lens glasses, with the HLG simulator turned on and off. A total of 8 conditions were used for each participant. Pedestrian detection response time. The 22 participants who completed the study included 12 younger (mean [SD] age, 28 [7] years; 6 men) individuals who responded to a pedestrian wearing a dark navy blue shirt, as well as 6 younger (mean [SD] age, 27 [4] years; 4 men) and 4 older (mean [SD], 70 [11] years; all men) participants who responded to a pedestrian in an orange shirt. All participants had normal visual acuity (mean [SD], -0.05 [0.06] logMAR). No significant difference in response time with yellow lens was found in all experiment conditions; younger participants for dark navy blue shirt pedestrians (F1,33 = 0.59; P = .45), orange shirt pedestrians (F1,15 = 0.13; P = .72), and older participants for orange shirt pedestrians (F1,9 = 0.84; P = .38). Among all participants (n = 22), no significant main effect of yellow lenses was found (F1,63 = 0.64; P = .42). In all measuring conditions, the response times with the yellow lenses were not better than with the clear lenses. Significant main effects of HLG were found with dark navy blue shirt pedestrian condition for young participants (F1,33 = 7.34; P < .001) and with orange shirt pedestrian condition for older individuals (F1,9 = 75.32; P < .001), where the difference in response time between with and without HLG was larger for older (1.5 seconds) than younger (0.3 seconds) participants. Using a driver simulator equipped with an HLG simulator, yellow-lens night-driving glasses did not appear to improve pedestrian detection at night or reduce the negative effects of HLG on pedestrian detection performance. These findings do not appear to support having eye care professionals advise patients to use yellow-lens night-driving glasses.

66‐4: Late‐News Paper: Fast Dichroic‐Dye‐Doped Cholesteric Liquid Crystals Light Shutter

We demonstrate a dichroic‐dye‐doped cholesteric liquid crystal light shutter device with fast response time, achromatic dark state, and polarization independence. The liquid crystal director is switching between the transparent homeotropic state to a dark transient planar state without scattering, and continually to focal conic state with little scattering. The device fabrication process is simple because of no alignment is needed and a simple electrodes structure used. It has potential to be applied in automotive applications to block oncoming headlight glare, and in AR real world image occlusion.

Design of a Modular Beam Control System for Vehicles

Abstract High intensity beams enable the drivers to survey a large portion of the road ahead of them at night. These beams are meant for use when there aren’t many vehicles around. However, a lot of drivers make use of these beams while driving because of the convenience of having a larger field of view. These beams often result in momentary partial blindness for drivers in the oncoming lane, causing them to become floundered. In such a state, they tend to lose control and cause accidents. In this paper, we propose a novel method to curb such happenings by automating the high beam and low beam settings of a vehicle. For the purpose of this study, we used a custom prototype, which is also discussed in detail. The solution we propose, if developed into a product, would be available as an add-on module, and if implemented appropriately, will reduce the accidents due to headlight glare by an exponential factor.

Impact of Oncoming Headlight Glare With Cataracts: A Pilot Study

Purpose: Oncoming headlight glare (HLG) reduces the visibility of objects on the road and may affect the safety of nighttime driving. With cataracts, the impact of oncoming HLG is expected to be more severe. We used our custom HLG simulator in a driving simulator to measure the impact of HLG on pedestrian detection by normal vision subjects with simulated mild cataracts and by patients with real cataracts.Methods: Five normal vision subjects drove nighttime scenarios under two HLG conditions (with and without HLG: HLGY and HLGN, respectively), and three vision conditions (with plano lens, simulated mild cataract, and optically blurred clip-on). Mild cataract was simulated by applying a 0.8 Bangerter diffusion foil to clip-on plano lenses. The visual acuity with the optically blurred lenses was individually chosen to match the visual acuity with the simulated cataract clip-ons under HLGN. Each nighttime driving scenario contains 24 pedestrian encounters, encompassing four pedestrian types; walking along the left side of the road, walking along the right side of the road, crossing the road from left to right, and crossing the road from right to left. Pedestrian detection performances of five patients with mild real cataracts were measured using the same setup. The cataract patients were tested only in HLGY and HLGN conditions. Participants’ visual acuity and contrast sensitivity were also measured in the simulator with and without stationary HLG.Results: For normal vision subjects, both the presence of oncoming HLG and wearing the simulated cataract clip-on reduced pedestrian detection performance. The subjects performed worst in events where the pedestrian crossed from the left, followed by events where the pedestrian crossed from the right. Significant interactions between HLG condition and other factors were also found: (1) the impact of oncoming HLG with the simulated cataract clip-on was larger than with the plano lens clip-on, (2) the impact of oncoming HLG was larger with the optically blurred clip-on than with the plano lens clip-on, but smaller than with the simulated cataract clip-on, and (3) the impact was larger for the pedestrians that crossed from the left than those that crossed from the right, and for the pedestrians walking along the left side of the road than walking along the right side of the road, suggesting that the pedestrian proximity to the glare source contributed to the performance reduction. Under HLGN, almost no pedestrians were missed with the plano lens or the simulated cataract clip-on (0 and 0.5%, respectively), but under HLGY, the rate of pedestrian misses increased to 0.5 and 6%, respectively. With the optically blurred clip-on, the percent of missed pedestrians under HLGN and HLGY did not change much (5% and 6%, respectively). Untimely response rate increased under HLGY with the plano lens and simulated cataract clip-ons, but the increase with the simulated cataract clip-on was significantly larger than with the plano lens clip-on. The contrast sensitivity with the simulated cataract clip-on was significantly degraded under HLGY. The visual acuity with the plano lens clip-on was significantly improved under HLGY, possibly due to pupil myosis. The impact of HLG measured for real cataract patients was similar to the impact on performance of normal vision subjects with simulated cataract clip-ons.Conclusion: Even with mild (simulated or real) cataracts, a substantial negative effect of oncoming HLG was measurable in the detection of crossing and walking-along pedestrians. The lowered pedestrian detection rates and longer response times with HLGY demonstrate a possible risk that oncoming HLG poses to patients driving with cataracts.

Creating headlight glare in a driving simulator

The glare of bright headlights from oncoming vehicles is a common challenge experienced by drivers at night. Glare can produce discomfort, which may cause drivers to squint or avert their gaze, and can also cause disability in terms of directly disrupting visual perception. The consequences of glare on measures of driving performance specifically are not well described, partially due to safety issues in attempting to evaluate glare effects during on-road driving. Driving simulators, however, provide a particularly useful interface through which to investigate these effects in a safe and systematic manner. That said, very few simulators include integrated glare effects, likely because these effects simply are not achievable with conventional display systems. Therefore, we developed a novel glare simulator that is able to reproduce the effect of bright headlights from oncoming traffic using a novel hybrid display system, combining traditional projectors with panels of high intensity light emitting diodes (LEDs) mounted on a robotic actuator. Each LED on these panels can be independently modulated, allowing the grid to present lights of various sizes and intensities in order to simulate oncoming vehicle headlights over a broad range of distances. In this paper the system design and the mapping to synchronize the two display systems are described, and the resultant effects are illustrated. Overall, glare is a common, yet problematic challenge during driving, therefore understanding precisely how this affects driving performance across different driver populations is of high importance.

The effectiveness of glare-reducing glasses on simulated nighttime driving performance in younger and older adults

Glare from oncoming headlights is a problem for nighttime drivers because it can decrease visual acuity and cause discomfort. This diminished visual ability and discomfort due can increase drivers’ risk for traffic accidents. Older drivers experience more severe detrimental effects from nighttime glare, and these effects may pose a growing roadway hazard as the number of older drivers increases. The increased brightness of popular high-intensity-discharge (HID) headlights may further exacerbate these visibility problems. In a sample of younger (under 40 years of age) and older (40 years of age and older) drivers, we examined the impact of headlight glare from HID and traditional halogen lights on driving performance in a simulator, as well as the effectiveness of novel polarized glare-reducing eyeglasses for mitigating glare-induced performance deficits. The glare-reducing glasses increased visual awareness in the face of oncoming HID headlights compared to halogen headlights in both age groups. Older drivers performed significantly worse than did younger drivers on several measures of driving and visual detection performance. The glare-reducing glasses mitigated performance deficits, with older drivers performing similarly to younger drivers when exposed to HID headlights while wearing the polarized glasses. Due to the introduction of brighter LED-based headlights to the consumer automotive market and an expanding population of older drivers, automotive manufactures should consider glare-mitigation strategies when designing future headlight systems.

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.

Observers' Judgments of the Effects of Glare on Their Visual Acuity for High and Low Contrast Stimuli.

Disability glare refers to a reduction in the ability to discern a stimulus that is positioned near another stimulus that has a much higher luminance. While it is common for drivers to report that they have been "blinded" by oncoming headlights, it is unclear whether observers can accurately judge when they are visually disabled by glare. This experiment sought to quantify the accuracy with which observers can judge when a glare source reduces their visual acuity. Seventeen observers estimated their disability glare threshold (DGT)-the luminance of a glare source that would be just sufficient to impair their ability to discern the orientation of a Landolt C that was surrounded by the glare source. These estimated DGTs were compared to the participant's actual DGTs. Participants consistently underestimated the intensity of glare that was required to impair their acuity. On average, estimates of glare threshold were 88% lower than actual glare threshold intensities. Participants' judgments were affected by stimulus size but not stimulus contrast. These results suggest that observers can exaggerate the debilitating effects of glare and that they can fail to appreciate that high contrast stimuli are more robust to glare. A driver who believes that even the lowest intensities of headlight glare can visually impair an oncoming driver may be reluctant to use high beam headlamps, despite their significant visibility advantages.

Market evaluation, performance modelling and materials solution addressing short wavelength discomfort glare in rear view automotive mirrors

Recent trends in automotive night time illumination have seen an increase in the use of short wavelength forward lighting, where high intensity discharge (HID) and light emitting diode (LED) headlamps are replacing traditional halogen headlamps. A targeted review of literature suggests short wavelength lighting produces significantly more discomfort glare for drivers. When designing an anti-glare rear view mirror, consideration should be given to all three headlamp glare sources currently on vehicles and their likely reflected glare effects on drivers. In this study a novel antiglare rear view mirror solution has been developed by means of a thin film interference coating formed by alternating silica and chrome layers. The antiglare mirrors performance has been evaluated in terms of glare reduction and object detection using a light ray tracing simulation package. Prototype samples have been validated under laboratory conditions demonstrating significant glare reduction whilst maintaining a high level of optical performance. This technology has been transferred to SMR Automotive Australia's high volume production facility.

Drivers' judgments of the effect of headlight glare on their ability to see pedestrians at night

IntroductionSeveral studies have concluded that pedestrians typically overestimate their own conspicuity to approaching drivers at night. The present experiments extended this research by exploring the accuracy of drivers' judgments of pedestrian conspicuity while facing varying degrees of headlight glare. MethodIn Experiment 1, participants on an open road estimated their ability to see a roadside pedestrian in each of two clothing configurations and with each of three different glare intensities present. In Experiment 2, participants responded to a roadside pedestrian under the same open road conditions; the participants were naïve with regard to both the position of the pedestrian and to the clothing and glare manipulations. ResultsConsistent with earlier research, estimates of response distance were, on the average, over three times greater than actual recognition distance. The extent to which participants overestimated conspicuity was greater when the pedestrian wore a retroreflective vest, and participants incorrectly judged that headlight glare would not degrade drivers' ability to see a pedestrian wearing a retroreflective vest. Conclusions and Practical ApplicationsThese results confirm that road users' understanding of issues involving drivers' night vision is limited. These misunderstandings may result in road users behaving in ways that increase the risk of nighttime collisions with pedestrians.

The accuracy of drivers' judgments of the effects of headlight glare on their own visual acuity.

Drivers' judgments of the magnitude of disability glare caused by high-beam headlights may not match actual declines in visual performance. This study investigated younger and older drivers' beliefs about their own visual performance in the presence of headlight glare. Eleven older drivers and seventeen younger drivers judged the distance at which they would just be able to recognize the orientation of a white Landolt C if it were present adjacent to the headlamps of a stationary opposing vehicle at night. The younger participants were generally accurate in their estimates of the recognition distance of the stimulus, while older participants significantly overestimated both their own acuity and the effect of glare on their vision. From this study, we see that older drivers' judgments about the disabling effects of oncoming headlights may be systematically inaccurate. These misperceptions about headlight glare may help explain why drivers tend to underuse high beams.