Pub Date : 2022-01-20DOI: 10.1080/15502724.2021.2001345
S. Peeters, K. Smolders, M. Kompier, Y. D. de Kort
ABSTRACT Throughout the day, we are exposed to light that varies drastically over time. Correct quantification of the light is important when predicting sleep and subjective alertness in the field, yet doing so, is a complex challenge. In the current manuscript, we explore the feasibility of a novel, practical method to quantify light exposure, based on the data collected in two field studies (in late spring and winter). Data include indicators of sleep, subjective alertness, and personal luminous exposure. We explored Time above Threshold (TaT) and Mean Light Timing above Threshold (MLiT) metrics, as well as their interaction, to quantify intensity, timing, and duration of light in testing not only circadian but also acute alerting effects of light in the field during office hours. For both measures, sensitivity analyses were performed across a large range of illuminance thresholds. The aim was to explore if these analyses would render indications for (a range of) effective thresholds, and to test if this alternative method of quantifying light would outperform simple averaging over specific time intervals. Despite the relatively small data set, the current approach seems promising particularly for predicting sleep: models performed slightly better than traditional models using average light exposure as predictor. More importantly, this method takes into account intensity, duration and timing, providing more detailed insights in the relation between luminous exposure and different outcome measures. We encourage this method to be explored further with larger data sets, discuss shortcomings of the current analyses and suggest potential directions for improvement.
{"title":"Let Me Count the Light. Accounting for Intensity, Duration and Timing of Light When Predicting Sleep and Subjective Alertness in Field Studies","authors":"S. Peeters, K. Smolders, M. Kompier, Y. D. de Kort","doi":"10.1080/15502724.2021.2001345","DOIUrl":"https://doi.org/10.1080/15502724.2021.2001345","url":null,"abstract":"ABSTRACT Throughout the day, we are exposed to light that varies drastically over time. Correct quantification of the light is important when predicting sleep and subjective alertness in the field, yet doing so, is a complex challenge. In the current manuscript, we explore the feasibility of a novel, practical method to quantify light exposure, based on the data collected in two field studies (in late spring and winter). Data include indicators of sleep, subjective alertness, and personal luminous exposure. We explored Time above Threshold (TaT) and Mean Light Timing above Threshold (MLiT) metrics, as well as their interaction, to quantify intensity, timing, and duration of light in testing not only circadian but also acute alerting effects of light in the field during office hours. For both measures, sensitivity analyses were performed across a large range of illuminance thresholds. The aim was to explore if these analyses would render indications for (a range of) effective thresholds, and to test if this alternative method of quantifying light would outperform simple averaging over specific time intervals. Despite the relatively small data set, the current approach seems promising particularly for predicting sleep: models performed slightly better than traditional models using average light exposure as predictor. More importantly, this method takes into account intensity, duration and timing, providing more detailed insights in the relation between luminous exposure and different outcome measures. We encourage this method to be explored further with larger data sets, discuss shortcomings of the current analyses and suggest potential directions for improvement.","PeriodicalId":49911,"journal":{"name":"Leukos","volume":"21 1","pages":"417 - 437"},"PeriodicalIF":3.6,"publicationDate":"2022-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85474525","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-01DOI: 10.1080/15502724.2021.1890115
William B Thompson, Robert A Shakespeare, Siyun Liu, Sarah H Creem-Regehr, Daniel J Kersten, Gordon E Legge
Most people with low vision rely on their remaining functional vision for mobility. Our goal is to provide tools to help design architectural spaces in which safe and effective mobility is possible by those with low vision---spaces that we refer to as visually accessible. We describe an approach that starts with a 3D CAD model of a planned space and produces labeled images indicating whether or not structures that are potential mobility hazards are visible at a particular level of low vision. There are two main parts to the analysis. The first, previously described, represents low-vision status by filtering a calibrated luminance image generated from the CAD model and associated lighting and materials information to produce a new image with unseen detail removed. The second part, described in this paper, uses both these filtered images and information about the geometry of the space obtained from the CAD model and related lighting and surface material specifications to produce a quantitative estimate of the likelihood of particular hazards being visible. We provide examples of the workflow required, a discussion of the novelty and implications of the approach, and a short discussion of needed future work.
{"title":"Evaluating the Visibility of Architectural Features for People with Low Vision -A Quantitative Approach.","authors":"William B Thompson, Robert A Shakespeare, Siyun Liu, Sarah H Creem-Regehr, Daniel J Kersten, Gordon E Legge","doi":"10.1080/15502724.2021.1890115","DOIUrl":"https://doi.org/10.1080/15502724.2021.1890115","url":null,"abstract":"<p><p>Most people with low vision rely on their remaining functional vision for mobility. Our goal is to provide tools to help design architectural spaces in which safe and effective mobility is possible by those with low vision---spaces that we refer to as <i>visually accessible</i>. We describe an approach that starts with a 3D CAD model of a planned space and produces labeled images indicating whether or not structures that are potential mobility hazards are visible at a particular level of low vision. There are two main parts to the analysis. The first, previously described, represents low-vision status by filtering a calibrated luminance image generated from the CAD model and associated lighting and materials information to produce a new image with unseen detail removed. The second part, described in this paper, uses both these filtered images and information about the geometry of the space obtained from the CAD model and related lighting and surface material specifications to produce a quantitative estimate of the likelihood of particular hazards being visible. We provide examples of the workflow required, a discussion of the novelty and implications of the approach, and a short discussion of needed future work.</p>","PeriodicalId":49911,"journal":{"name":"Leukos","volume":"18 2","pages":"154-172"},"PeriodicalIF":3.6,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/15502724.2021.1890115","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10463888","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-16DOI: 10.1080/15502724.2021.1993893
R. Spieringhs, Kevin A. G. Smet, I. Heynderickx, P. Hanselaer
ABSTRACT Sufficient contrast between road surface and road markings is key for a safe and comfortable driving experience. This calls for a comprehensive and well established contrast (threshold) model, which ideally results in a single contrast threshold value independent of object angular size or road luminance. The contrast threshold model introduced by Adrian is still commonly used in road lighting. More recently, new contrast metrics that also predict supra-threshold contrast visibility have been proposed, but the corresponding visibility thresholds are not yet known. In the present study, participants are presented a rendering of a highway, including road marking arrows of various size and luminance and were asked to indicate the direction of the arrow. The luminance of the road surface, acting as background for the markings, was varied too. Due to the very low luminance values and the very small differences in luminance, measurement accuracy and calibration issues require special attention. The results show good agreement with Adrian’s visibility model (R2 = 0.75) in terms of luminance contrast, background luminance and size. In addition, we used our experimental data to define contrast thresholds for several other existing image based contrast models. Unfortunately, it seems to be impossible to state one unique threshold contrast value independent of object angular size and road luminance.
{"title":"Road Marking Contrast Threshold Revisited","authors":"R. Spieringhs, Kevin A. G. Smet, I. Heynderickx, P. Hanselaer","doi":"10.1080/15502724.2021.1993893","DOIUrl":"https://doi.org/10.1080/15502724.2021.1993893","url":null,"abstract":"ABSTRACT Sufficient contrast between road surface and road markings is key for a safe and comfortable driving experience. This calls for a comprehensive and well established contrast (threshold) model, which ideally results in a single contrast threshold value independent of object angular size or road luminance. The contrast threshold model introduced by Adrian is still commonly used in road lighting. More recently, new contrast metrics that also predict supra-threshold contrast visibility have been proposed, but the corresponding visibility thresholds are not yet known. In the present study, participants are presented a rendering of a highway, including road marking arrows of various size and luminance and were asked to indicate the direction of the arrow. The luminance of the road surface, acting as background for the markings, was varied too. Due to the very low luminance values and the very small differences in luminance, measurement accuracy and calibration issues require special attention. The results show good agreement with Adrian’s visibility model (R2 = 0.75) in terms of luminance contrast, background luminance and size. In addition, we used our experimental data to define contrast thresholds for several other existing image based contrast models. Unfortunately, it seems to be impossible to state one unique threshold contrast value independent of object angular size and road luminance.","PeriodicalId":49911,"journal":{"name":"Leukos","volume":"35 1","pages":"493 - 512"},"PeriodicalIF":3.6,"publicationDate":"2021-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78106721","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-29DOI: 10.1080/15502724.2021.1988819
K. Houser
Researchers and practitioners in fields that include lighting science and illuminating engineering endeavor to balance objectivity with skepticism. Conviction is warranted when a position can be supported by robust and reliable data—e.g., vision deteriorates with age. Skepticism is warranted when supporting data are incomplete or unconvincing. For example, while there is no doubt that light mediates nonvisual responses such as melatonin suppression, the manner and degree to which that knowledge should inform lighting practice is less clear. When recommendations run too far ahead of what is known with conviction, it is prudent to be skeptical. Authors and speakers also persuade their audiences through narratives—stories that connect carefully selected sets of supposedly true observations. Conclusions are convincing when they can be supported by credible data, yet data tend to be curated, partial, and even when exhibiting internal validity may not apply to other contexts. Scientific viewpoints tend to be justified with intrinsically limited data that is chronicled through cogent narratives. For people seeking the ground truth, this process is exciting. Ideas are interrogated, caveats are stated, alternative explanations are considered, and degrees of both certainty and doubt are weighed. To someone outside of the scientific process, doubt may appear troubling, and certainty may be reassuring, but to a researcher, it is quite the opposite. Doubt pushes science toward deeper understanding, whereas certainty can be the bane of curiosity that impedes progress. While more research and more data will always be needed, considered choices can be made based on what is known. It is healthy to acknowledge that knowledge is incomplete, letting neither rational uncertainty nor irrational conviction stand in the way of progress. When faced with new data, changing one’s mind is not a failure, but a sign of growth. Formal discourse unfolds in the scientific literature, which relies on peer reviews to assess the credibility and veracity of scientific works. But the end goal of scientific works, especially in applied journals like LEUKOS, is not publication of the article, but the potential of the work to positively influence the world. This requires transfer of ideas or technologies from the scientific community to the public, a step that sometimes meets resistance. In recent years, there has been widespread erosion in the objective standards for truth. Public opinions are shaped by personal beliefs that are themselves influenced by appeals to emotion. Half-truths and outright falsehoods are sometimes promulgated to misinform. Does stating something false makes it true? An impartial reader might answer “no,” but in important domains of life that include politics and public policy, there is a blurry line between the rational and the fanciful. The repetition of false statements repeated ad nauseam and with conviction, has for some sowed seeds of doubt in science itse
{"title":"Certainty and Doubt","authors":"K. Houser","doi":"10.1080/15502724.2021.1988819","DOIUrl":"https://doi.org/10.1080/15502724.2021.1988819","url":null,"abstract":"Researchers and practitioners in fields that include lighting science and illuminating engineering endeavor to balance objectivity with skepticism. Conviction is warranted when a position can be supported by robust and reliable data—e.g., vision deteriorates with age. Skepticism is warranted when supporting data are incomplete or unconvincing. For example, while there is no doubt that light mediates nonvisual responses such as melatonin suppression, the manner and degree to which that knowledge should inform lighting practice is less clear. When recommendations run too far ahead of what is known with conviction, it is prudent to be skeptical. Authors and speakers also persuade their audiences through narratives—stories that connect carefully selected sets of supposedly true observations. Conclusions are convincing when they can be supported by credible data, yet data tend to be curated, partial, and even when exhibiting internal validity may not apply to other contexts. Scientific viewpoints tend to be justified with intrinsically limited data that is chronicled through cogent narratives. For people seeking the ground truth, this process is exciting. Ideas are interrogated, caveats are stated, alternative explanations are considered, and degrees of both certainty and doubt are weighed. To someone outside of the scientific process, doubt may appear troubling, and certainty may be reassuring, but to a researcher, it is quite the opposite. Doubt pushes science toward deeper understanding, whereas certainty can be the bane of curiosity that impedes progress. While more research and more data will always be needed, considered choices can be made based on what is known. It is healthy to acknowledge that knowledge is incomplete, letting neither rational uncertainty nor irrational conviction stand in the way of progress. When faced with new data, changing one’s mind is not a failure, but a sign of growth. Formal discourse unfolds in the scientific literature, which relies on peer reviews to assess the credibility and veracity of scientific works. But the end goal of scientific works, especially in applied journals like LEUKOS, is not publication of the article, but the potential of the work to positively influence the world. This requires transfer of ideas or technologies from the scientific community to the public, a step that sometimes meets resistance. In recent years, there has been widespread erosion in the objective standards for truth. Public opinions are shaped by personal beliefs that are themselves influenced by appeals to emotion. Half-truths and outright falsehoods are sometimes promulgated to misinform. Does stating something false makes it true? An impartial reader might answer “no,” but in important domains of life that include politics and public policy, there is a blurry line between the rational and the fanciful. The repetition of false statements repeated ad nauseam and with conviction, has for some sowed seeds of doubt in science itse","PeriodicalId":49911,"journal":{"name":"Leukos","volume":"680 1","pages":"1 - 1"},"PeriodicalIF":3.6,"publicationDate":"2021-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76278934","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-05DOI: 10.1080/15502724.2021.1970580
E. Vicente, B. Matesanz, M. Rodríguez-Rosa, A. M. Sáez, S. Mar, I. Arranz
ABSTRACT The increasing replacement of traditional lamps by LED technology opens the door to research into visual performance under their multiple possible spectral power distributions. The correlated color temperature and S/P-ratio are considered parameters characterizing the spectrum of a light source. The lack of firm conclusions motivates the analysis in this work of the influence of LED spectrum, which is defined by the correlated color temperature and S/P-ratio, on a representative night-driving task, visual reaction time. A two-channel and four primaries photostimulator was used as set-up for measuring reaction time in off-axis vision, at mesopic illumination conditions and for a range of stimulus contrasts. The experimental conditions included a wide range of correlated color temperatures, ranging from 1870 to 6350 K, and different S/P-ratios for the same temperature. A total of 16 young subjects participated in the experiments. The results show significant shorter reaction times for those conditions in which the spectrum has greater short-wavelength content. This is corroborated by the greater stimulation of rods and S-cones obtained in the calculation of their excitation level. However, the definition of the spectrum using the correlated color temperature and S/P-ratio does not equally define the results obtained. For the same temperature, a higher S/P-ratio provides lower reaction time values, but for the same S/P ratio reaction time is independent of the temperature. LED light sources with high short-wavelength content provide faster response on the basis of a greater excitation of rods and S-cones. The S/P-ratio is the best parameter to justify the effect of spectrum on reaction time, as considers the spectral sensitivity of the visual system in its calculation.
{"title":"Effect of Correlated Color Temperature and S/P-ratio of LED Light Sources on Reaction Time in Off-axis Vision and Mesopic Lighting Levels","authors":"E. Vicente, B. Matesanz, M. Rodríguez-Rosa, A. M. Sáez, S. Mar, I. Arranz","doi":"10.1080/15502724.2021.1970580","DOIUrl":"https://doi.org/10.1080/15502724.2021.1970580","url":null,"abstract":"ABSTRACT The increasing replacement of traditional lamps by LED technology opens the door to research into visual performance under their multiple possible spectral power distributions. The correlated color temperature and S/P-ratio are considered parameters characterizing the spectrum of a light source. The lack of firm conclusions motivates the analysis in this work of the influence of LED spectrum, which is defined by the correlated color temperature and S/P-ratio, on a representative night-driving task, visual reaction time. A two-channel and four primaries photostimulator was used as set-up for measuring reaction time in off-axis vision, at mesopic illumination conditions and for a range of stimulus contrasts. The experimental conditions included a wide range of correlated color temperatures, ranging from 1870 to 6350 K, and different S/P-ratios for the same temperature. A total of 16 young subjects participated in the experiments. The results show significant shorter reaction times for those conditions in which the spectrum has greater short-wavelength content. This is corroborated by the greater stimulation of rods and S-cones obtained in the calculation of their excitation level. However, the definition of the spectrum using the correlated color temperature and S/P-ratio does not equally define the results obtained. For the same temperature, a higher S/P-ratio provides lower reaction time values, but for the same S/P ratio reaction time is independent of the temperature. LED light sources with high short-wavelength content provide faster response on the basis of a greater excitation of rods and S-cones. The S/P-ratio is the best parameter to justify the effect of spectrum on reaction time, as considers the spectral sensitivity of the visual system in its calculation.","PeriodicalId":49911,"journal":{"name":"Leukos","volume":"67 1","pages":"4 - 15"},"PeriodicalIF":3.6,"publicationDate":"2021-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79830599","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-02DOI: 10.1080/15502724.2021.1951021
K. Houser
Human-centered design is a problem-solving approach that focuses on people first—their productivity, comfort, and user experience. A bicycle should be designed with pedals, seat, handlebars, brakes, and gear shifters in ergonomically comfortable positions. The hardware and software that comprise tablets and cellular devices should intuitively enable a positive user experience. Placing humans first is a sensible approach in many design scenarios, especially when the device or technology will not substantially interact with non-human life. With lighting, however, human-centricity may come with collateral damage. Through Earth’s web of life, we rely on other forms of life for our own survival. As apex predators, humans consume all kinds of plants and animals, which themselves are part of wider and interconnected ecosystems consisting of all manner of biotic and abiotic components. Regrettably and incontrovertibly, some lighting designed to support a subset of human needs causes unintended negative effects on human life, and even worse consequences to nonhuman life. Artificial light at night (ALAN) is offered as a case in point. Notwithstanding some practical and aesthetic benefits, ALAN exerts direct negative effects on people. The human body tells time by observing nature’s rhythm of light and dark. Electric lighting that is asynchronous with natural cycles of day and night may interfere with our natural biological clocks, thus impairing human functioning on timescales of days, weeks, and years. Simultaneously, ALAN disrupts natural ecosystems. Flora and fauna rely on Earth’s predictable patterns of day and night to regulate life-sustaining behaviors such as sleep, eating, reproduction, and hiding from predators. ALAN disrupts those behaviors. Some species gain a short-term advantage at the expense of other species, thus disrupting ecosystems. These disturbances may not show immediate or obvious effects on humans, but this is more reflective of the inability of human science to predict, detect, and measure such effects. On timescales of decades and generations, we should expect the consequences to come back to us. Holistic consideration of human-centric lighting should look beyond short-term effects of light on human visual, emotional, behavioral, and biological outcomes. While ethical considerations related to conserving habitats for turtles, birds, insects, fishes, and reptiles are salient, this is not mere altruism. Nor is this just romanticism about the beauty of the night sky. At root is also pragmatism. It is in our self-interest to preserve the ecosystems and biodiversity that support human life, lest today’s design decisions become tomorrow’s liabilities. How might one practice lighting if short-term considerations about human needs yield to, or better, integrate with, long-term considerations about planetary health? To what degree, if at all, should building facades and monuments be illuminated? To what degree should window shading devices
{"title":"Ethics and Fallacies of Human-Centric Lighting and Artificial Light at Night","authors":"K. Houser","doi":"10.1080/15502724.2021.1951021","DOIUrl":"https://doi.org/10.1080/15502724.2021.1951021","url":null,"abstract":"Human-centered design is a problem-solving approach that focuses on people first—their productivity, comfort, and user experience. A bicycle should be designed with pedals, seat, handlebars, brakes, and gear shifters in ergonomically comfortable positions. The hardware and software that comprise tablets and cellular devices should intuitively enable a positive user experience. Placing humans first is a sensible approach in many design scenarios, especially when the device or technology will not substantially interact with non-human life. With lighting, however, human-centricity may come with collateral damage. Through Earth’s web of life, we rely on other forms of life for our own survival. As apex predators, humans consume all kinds of plants and animals, which themselves are part of wider and interconnected ecosystems consisting of all manner of biotic and abiotic components. Regrettably and incontrovertibly, some lighting designed to support a subset of human needs causes unintended negative effects on human life, and even worse consequences to nonhuman life. Artificial light at night (ALAN) is offered as a case in point. Notwithstanding some practical and aesthetic benefits, ALAN exerts direct negative effects on people. The human body tells time by observing nature’s rhythm of light and dark. Electric lighting that is asynchronous with natural cycles of day and night may interfere with our natural biological clocks, thus impairing human functioning on timescales of days, weeks, and years. Simultaneously, ALAN disrupts natural ecosystems. Flora and fauna rely on Earth’s predictable patterns of day and night to regulate life-sustaining behaviors such as sleep, eating, reproduction, and hiding from predators. ALAN disrupts those behaviors. Some species gain a short-term advantage at the expense of other species, thus disrupting ecosystems. These disturbances may not show immediate or obvious effects on humans, but this is more reflective of the inability of human science to predict, detect, and measure such effects. On timescales of decades and generations, we should expect the consequences to come back to us. Holistic consideration of human-centric lighting should look beyond short-term effects of light on human visual, emotional, behavioral, and biological outcomes. While ethical considerations related to conserving habitats for turtles, birds, insects, fishes, and reptiles are salient, this is not mere altruism. Nor is this just romanticism about the beauty of the night sky. At root is also pragmatism. It is in our self-interest to preserve the ecosystems and biodiversity that support human life, lest today’s design decisions become tomorrow’s liabilities. How might one practice lighting if short-term considerations about human needs yield to, or better, integrate with, long-term considerations about planetary health? To what degree, if at all, should building facades and monuments be illuminated? To what degree should window shading devices","PeriodicalId":49911,"journal":{"name":"Leukos","volume":"10 1","pages":"319 - 320"},"PeriodicalIF":3.6,"publicationDate":"2021-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83660843","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-09DOI: 10.1080/15502724.2021.1957688
R. A. Mangkuto, M. Koerniawan
ABSTRACT The concept of illumination vector quantities at a given point in three-dimensional space has been proposed since long time ago, but it is mostly described for scenes with point light sources. In real scenes with area light sources, numerical approximations are required to estimate the illumination vector quantities, which can be done by discretising the area into an array of point sources. Two different approaches are proposed in this study; Approach 1 is applicable in the design phase, where the positions of the source and receiver point are exactly known. Approach 2 is applicable during field measurement, based on the obtained cubic illuminances. This study aims to determine the required number of point source elements in the computation and to investigate the difference between both calculation approaches. The proposed concept is demonstrated using a scenario with horizontal, square source and a scenario with vertical, rectangular source, with various luminous intensity distribution patterns, by observing various illumination vector quantities. Grid sensitivity analyses suggest that the largest grid size satisfying the five-to-one approximation rule shall yield quantities that converge within no more than 5% to the final value. For a given size of area source, at a given distance, the differences of illumination vector quantities obtained from both calculation approaches are expected to be approximately the same, regardless the luminous intensity distribution. The estimation of cylindrical illuminance is generally more accurate than that of scalar illuminance.
{"title":"On Illumination Vector Quantities Due to Area Light Sources: Comparison of Two Calculation Approaches","authors":"R. A. Mangkuto, M. Koerniawan","doi":"10.1080/15502724.2021.1957688","DOIUrl":"https://doi.org/10.1080/15502724.2021.1957688","url":null,"abstract":"ABSTRACT The concept of illumination vector quantities at a given point in three-dimensional space has been proposed since long time ago, but it is mostly described for scenes with point light sources. In real scenes with area light sources, numerical approximations are required to estimate the illumination vector quantities, which can be done by discretising the area into an array of point sources. Two different approaches are proposed in this study; Approach 1 is applicable in the design phase, where the positions of the source and receiver point are exactly known. Approach 2 is applicable during field measurement, based on the obtained cubic illuminances. This study aims to determine the required number of point source elements in the computation and to investigate the difference between both calculation approaches. The proposed concept is demonstrated using a scenario with horizontal, square source and a scenario with vertical, rectangular source, with various luminous intensity distribution patterns, by observing various illumination vector quantities. Grid sensitivity analyses suggest that the largest grid size satisfying the five-to-one approximation rule shall yield quantities that converge within no more than 5% to the final value. For a given size of area source, at a given distance, the differences of illumination vector quantities obtained from both calculation approaches are expected to be approximately the same, regardless the luminous intensity distribution. The estimation of cylindrical illuminance is generally more accurate than that of scalar illuminance.","PeriodicalId":49911,"journal":{"name":"Leukos","volume":"48 1","pages":"475 - 492"},"PeriodicalIF":3.6,"publicationDate":"2021-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90121024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-08-26DOI: 10.1080/15502724.2021.1954531
Joffrey Girard, C. Villa, R. Brémond
ABSTRACT Many models of discomfort glare have been proposed for outdoor lighting applications. Most of them were built from data collected in the laboratory in static situations, with motionless light sources, which main characteristics (luminance, size and position) were constant over time. However, on the road at night, drivers are moving with multiple sources around them. To fill the gap between static situations and more realistic ones, four psychophysic experiments were carried out in a laboratory to investigate the impact of the cyclic variations of several light source characteristics (its luminance, eccentricity and solid angle) on the discomfort glare. The temporal frequencies have been chosen representative of outdoor lighting conditions, up to 2.6 Hz. No impact of the dynamics of the glare source was found, except for a source with variable luminance at a low frequency ( ).
{"title":"Discomfort Glare from a Cyclic Source in Outdoor Lighting Conditions","authors":"Joffrey Girard, C. Villa, R. Brémond","doi":"10.1080/15502724.2021.1954531","DOIUrl":"https://doi.org/10.1080/15502724.2021.1954531","url":null,"abstract":"ABSTRACT Many models of discomfort glare have been proposed for outdoor lighting applications. Most of them were built from data collected in the laboratory in static situations, with motionless light sources, which main characteristics (luminance, size and position) were constant over time. However, on the road at night, drivers are moving with multiple sources around them. To fill the gap between static situations and more realistic ones, four psychophysic experiments were carried out in a laboratory to investigate the impact of the cyclic variations of several light source characteristics (its luminance, eccentricity and solid angle) on the discomfort glare. The temporal frequencies have been chosen representative of outdoor lighting conditions, up to 2.6 Hz. No impact of the dynamics of the glare source was found, except for a source with variable luminance at a low frequency ( ).","PeriodicalId":49911,"journal":{"name":"Leukos","volume":"14 1","pages":"459 - 474"},"PeriodicalIF":3.6,"publicationDate":"2021-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81926827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-08-10DOI: 10.1080/15502724.2021.1947313
R. Sadeghi, R. Mistrick
ABSTRACT The accuracy of daylighting simulations for the built environment strongly depends on the modeling of the exterior surround. The practice of modeling a space with a flat ground surface with little or no external architectural or landscape elements, particularly early in the design phase, is often applied. In this study, this approach and a number of different levels of detail for modeling the exterior surround were investigated by comparing real-life empirical measurements with their corresponding simulation results. A total of 13 different exterior views were studied under 15 different sky/seasonal conditions to investigate the contribution of the surrounding features to the daylight delivered inside a small office. These features were classified into one of four different groups – sky, architectural structures, standing vegetation, and horizontal ground. Five of these locations were chosen for further simulation by applying six levels of detail to the exterior surround in a simulation model. The results reveal that ignoring exterior surround objects (common practice for some) yielded an average error of 67.9%, while a high level of detail (which applied high polygon vegetation representations) resulted in an average error of only 11.3%. A detailed model of the surround with the IES LM-83 suggested method of modeling trees resulted in an average error of 22.8%.
{"title":"The Impact of Exterior Surround Detail on Daylighting Simulation Results","authors":"R. Sadeghi, R. Mistrick","doi":"10.1080/15502724.2021.1947313","DOIUrl":"https://doi.org/10.1080/15502724.2021.1947313","url":null,"abstract":"ABSTRACT The accuracy of daylighting simulations for the built environment strongly depends on the modeling of the exterior surround. The practice of modeling a space with a flat ground surface with little or no external architectural or landscape elements, particularly early in the design phase, is often applied. In this study, this approach and a number of different levels of detail for modeling the exterior surround were investigated by comparing real-life empirical measurements with their corresponding simulation results. A total of 13 different exterior views were studied under 15 different sky/seasonal conditions to investigate the contribution of the surrounding features to the daylight delivered inside a small office. These features were classified into one of four different groups – sky, architectural structures, standing vegetation, and horizontal ground. Five of these locations were chosen for further simulation by applying six levels of detail to the exterior surround in a simulation model. The results reveal that ignoring exterior surround objects (common practice for some) yielded an average error of 67.9%, while a high level of detail (which applied high polygon vegetation representations) resulted in an average error of only 11.3%. A detailed model of the surround with the IES LM-83 suggested method of modeling trees resulted in an average error of 22.8%.","PeriodicalId":49911,"journal":{"name":"Leukos","volume":"124 2 1","pages":"341 - 356"},"PeriodicalIF":3.6,"publicationDate":"2021-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88475086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-21DOI: 10.1080/15502724.2021.1925129
L. Simonot, F. Reux, S. Carré, C. Martinsons
ABSTRACT In lighting simulations, a luminaire is usually modeled using a luminous intensity distribution emitted by a single-point source. This so-called far-field approach is valid as long as the dimensions of the luminaire are much smaller than the distance to the calculation surface. This assumption is generally not met in standard indoor lighting and may lead to significant errors in the prediction of illuminances and discomfort glare. This work describes a practical near-field approach based on splitting the luminaire into N point sources. The errors in relation to the near field (infinite value of N) are evaluated as a function of N. This approach generates a more accurate assessment of the Unified Glare Rating in the case of luminaires with non-uniform emission.
{"title":"The Usefulness of Near-Field Goniophotometry Data to Assess Illuminances and Discomfort Glare in Indoor Lighting","authors":"L. Simonot, F. Reux, S. Carré, C. Martinsons","doi":"10.1080/15502724.2021.1925129","DOIUrl":"https://doi.org/10.1080/15502724.2021.1925129","url":null,"abstract":"ABSTRACT In lighting simulations, a luminaire is usually modeled using a luminous intensity distribution emitted by a single-point source. This so-called far-field approach is valid as long as the dimensions of the luminaire are much smaller than the distance to the calculation surface. This assumption is generally not met in standard indoor lighting and may lead to significant errors in the prediction of illuminances and discomfort glare. This work describes a practical near-field approach based on splitting the luminaire into N point sources. The errors in relation to the near field (infinite value of N) are evaluated as a function of N. This approach generates a more accurate assessment of the Unified Glare Rating in the case of luminaires with non-uniform emission.","PeriodicalId":49911,"journal":{"name":"Leukos","volume":"33 1","pages":"246 - 257"},"PeriodicalIF":3.6,"publicationDate":"2021-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82343199","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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