Precomputed low-frequency lighting in cinematic volume rendering.

Cinematic Rendering (CR) employs physical models such as ray tracing and global illumination to simulate real-world light phenomena, producing high-quality images with rich details. In the medical field, CR can significantly aid doctors in accurate diagnosis and preoperative planning. However, doctors require efficient real-time rendering when using CR, which presents a challenge due to the substantial computing resources demanded by CR's ray tracing and global illumination models. Precomputed lighting can enhance the efficiency of real-time rendering by freezing certain scene variables. Typically, precomputed methods freeze geometry and materials. However, since the physical rendering of medical images relies on volume data rendering of transfer functions, the CR algorithm cannot utilize precomputed methods directly. To improve the rendering efficiency of the CR algorithm, we propose a precomputed low-frequency lighting method. By simulating the lighting pattern of shadowless surgical lamps, we adopt a spherical distribution of multiple light sources, with each source capable of illuminating the entire volume of data. Under the influence of these large-area multi-light sources, the precomputed lighting adheres to physical principles, resulting in shadow-free and uniformly distributed illumination. We integrated this precomputed method into the ray-casting algorithm, creating an accelerated CR algorithm that achieves more than twice the rendering efficiency of traditional CR rendering.

We're All Healthier Under a Starry Sky.

A star-filled sky has long been a source of awe and inspiration, and its loss adversely affects human, nonhuman, and environmental health. In one generation, this majestic nighttime overstory has been lost due to national and international overuse of light-emitting diodes lighting. This article canvasses ill health effects of excessive light at night. Blue wavelengths of light are damaging to many forms of life, and glare from unshielded light compromises road safety and infiltrates bedrooms, suppressing melatonin production, undermining sleep quality and duration, and exacerbating susceptibility to many kinds of illness.

Investigating the effects of indoor lighting on measures of brain health in older adults: protocol for a cross-over randomized controlled trial.

BACKGROUND: The worldwide number of adults aged 60 years and older is expected to double from 1 billion in 2019 to 2.1 billion by 2050. As the population lives longer, the rising incidence of chronic diseases, cognitive disorders, and behavioral health issues threaten older adults' health span. Exercising, getting sufficient sleep, and staying mentally and socially active can improve quality of life, increase independence, and potentially lower the risk for Alzheimer's disease or other dementias. Nonpharmacological approaches might help promote such behaviors. Indoor lighting may impact sleep quality, physical activity, and cognitive function. Dynamically changing indoor lighting brightness and color throughout the day has positive effects on sleep, cognitive function, and physical activity of its occupants. The aim of this study is to investigate how different indoor lighting conditions affect such health measures to promote healthier aging. METHODS: This protocol is a randomized, cross-over, single-site trial followed by an exploratory third intervention. Up to 70 older adults in independent living residences at a senior living facility will be recruited. During this 16-week study, participants will experience three lighting conditions. Two cohorts will first experience a static and a dynamic lighting condition in a cluster-randomized cross-over design. The static condition lighting will have fixed brightness and color to match lighting typically provided in the facility. For the dynamic condition, brightness and color will change throughout the day with increased brightness in the morning. After the cross-over, both cohorts will experience another dynamic lighting condition with increased morning brightness to determine if there is a saturation effect between light exposure and health-related measures. Light intake, sleep quality, and physical activity will be measured using wearable devices. Sleep, cognitive function, mood, and social engagement will be assessed using surveys and cognitive assessments. DISCUSSION: We hypothesize participants will have better sleep quality and greater physical activity during the dynamic lighting compared to the static lighting condition. Additionally, we hypothesize there is a maximal threshold at which health-outcomes improve based on light exposure. Study findings may identify optimal indoor lighting solutions to promote healthy aging for older adults. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT05978934.

Skin Tone Analysis Through Skin Tone Map Generation With Optical Approach and Deep Learning.

BACKGROUND: Skin tone assessment is critical in both cosmetic and medical fields, yet traditional methods like the individual typology angle (ITA) have limitations, such as sensitivity to illuminants and insensitivity to skin redness. METHODS: This study introduces an automated image-based method for skin tone mapping by applying optical approaches and deep learning. The method generates skin tone maps by leveraging the illuminant spectrum, segments the skin region from face images, and identifies the corresponding skin tone on the map. The method was evaluated by generating skin tone maps under three standard illuminants (D45, D65, and D85) and comparing the results with those obtained using ITA on skin tone simulation images. RESULTS: The results showed that skin tone maps generated under the same lighting conditions as the image acquisition (D65) provided the highest accuracy, with a color difference of around 6, which is more than twice as small as those observed under other illuminants. The mapping positions also demonstrated a clear correlation with pigment levels. Compared to ITA, the proposed approach was particularly effective in distinguishing skin tones related to redness. CONCLUSION: Despite the need to measure the illuminant spectrum and for further physiological validation, the proposed approach shows potential for enhancing skin tone assessment. Its ability to mitigate the effects of illuminants and distinguish between the two dominant pigments offers promising applications in both cosmetic and medical diagnostics.

A Child-Friendly Wearable Device for Quantifying Environmental Risk Factors for Myopia.

Purpose: In the past few decades, the prevalence of myopia, where the eye grows too long, has increased dramatically. The visual environment appears to be critical to regulating the eye growth. Thus, it is very important to determine the properties of the environment that put children at risk for myopia. Researchers have suggested that the intensity of illumination and range of distances to which a child's eyes are exposed are important, but this has not been confirmed. Methods: We designed, built, and tested an inexpensive, child-friendly, head-mounted device that can measure the intensity and spectral content of illumination approaching the eyes and can also measure the distances to which the central visual field of the eyes are exposed. The device is mounted on a child's bicycle helmet. It includes a camera that measures distances over a substantial range and a six-channel spectral sensor. The sensors are hosted by a light-weight, battery-powered microcomputer. We acquired pilot data from children while they were engaged in various indoor and outdoor activities. Results: The device proved to be comfortable, easy, and safe to wear, and able to collect very useful data on the statistics of illumination and distances. Conclusions: The designed device is an ideal tool to be used in a population of young children, some of whom will later develop myopia and some of whom will not. Translational Relevance: Such data would be critical for determining the properties of the visual environment that put children at risk for becoming myopic.

Measurements of chromatic adaptation and luminous efficiency while wearing colored filters.

The visual system adapts dynamically to stabilize perception over widely varying illuminations. Such adaptation allows the colors of objects to appear constant despite changes in spectral illumination. Similarly, the wearing of colored filters also alters spectral content, but this alteration can be more extreme than typically encountered in nature, presenting a unique challenge to color constancy mechanisms. While it is known that chromatic adaptation is affected by surrounding spatial context, a recent study reported a gradual temporal adaptation effect to colored filters such that colors initially appear strongly shifted but over hours of wear are perceived as closer to an unfiltered appearance. Presently, it is not clear whether the luminance system adapts spatially and temporally like the chromatic system. To address this, spatial and temporal adaptation effects to a colored filter were measured using tasks that assess chromatic and luminance adaptation separately. Prior to and for 1 hour after putting on a pair of colored filters, participants made achromatic and heterochromatic flicker photometry (HFP) settings to measure chromatic and luminance adaptation, respectively. Results showed significant chromatic adaptation with achromatic settings moving closer to baseline settings over 1 hour of wearing the filters and greater adaptation with spatial context. Conversely, there was no significant luminance adaptation and HFP matches fell close to what was predicted photometrically. The results are discussed in the context of prior studies of chromatic and luminance adaptation.

Interactive correlations between artificial light at night, health risk behaviors, and cardiovascular health among patients with diabetes: A cross-sectional study.

BACKGROUND: Artificial light at night (ALAN) is a common phenomenon and contributes to the severe light pollution suffered by more than 80% of the world's population. This study aimed to evaluate the relationship between outdoor ALAN exposure and cardiovascular health (CVH) in patients with diabetes and the influence of various modifiable factors. METHODS: A survey method based on the China Diabetes and Risk Factor Monitoring System was adopted. Study data were extracted for 1765 individuals with diabetes in Anhui Province. Outdoor ALAN exposure (nW/cm2/sr) within 1000 m of each participant's residential address was obtained from satellite imagery data, with a resolution of ~1000 m. Health risk behaviors (HRBs) were measured via a standardized questionnaire. A linear regression model was employed to estimate the relationship between outdoor ALAN, HRBs, and CVH. RESULTS: Participants' mean age was 59.10 ± 10.0 years. An association was observed between ALAN and CVH in patients with diabetes (ß = 0.205) and exercise (ß = -1.557), moderated by HRBs, or metabolic metrics. There was an association between ALAN, ALAN, vegetable intake, and CVH. CONCLUSIONS: Exploring the relationship between ALAN exposure and cardiovascular and metabolic health provides policy data for improving light pollution strategies and reducing the risk of cardiovascular and metabolic disease in patients with diabetes.

Effects of dim-evening lighting optimised for geographical orientation versus standard lighting on mental health: protocol paper for a quasiexperimental study in a psychiatric hospital.

INTRODUCTION: Research has provided novel insights into how light stimulates circadian rhythms through specialised retinal ganglion cells to the suprachiasmatic nucleus. In addition, there has been a revolution in light-emitting diode (LED) technology, leading to tunable LED light sources and lighting systems, enabling 24-hour dynamic light scenarios with bright blue-enriched short wavelength light during the day and dim evening light, stimulating the circadian system. These dynamic LED lighting systems are now being implemented at hospitals without adequate understanding of how it may affect the health and well-being of patients and staff. METHODS AND ANALYSIS: An optimised dynamic LED lighting scenario is investigated at a newly built psychiatric hospital in Copenhagen. In the 12 months baseline period, a standard lighting scenario with dynamic colour temperature and fixed light intensity is investigated. In the following 12-month intervention period, a new DEL scenario is investigated, having dynamic colour temperature as well as dynamic light intensity with a higher daytime and lower evening-time melanopic daylight equivalent illuminance. This setting is furthermore adjusted for geographical orientation to compensate for differences in sunlight access in wintertime. The study uses a quasiexperimental design comparing patients admitted in the two study periods. Prior to each of the study periods, daylight and the contribution from the LED-lighting scenarios was measured. Patient sociodemographic and mental health data will be retrieved retrospectively from electronic medical records and by questionnaires administered in the two periods, evaluating lighting, noise, sleep quality and quality of life. Primary outcome is the proportion of patients receiving pro re nata medications. Secondary outcomes are the length of stay, sleep onset latency, sleep quality and quality of life. ETHICS AND DISSEMINATION: No ethical issues are expected. The results will be disseminated through peer-reviewed international journal, lectures, posters and interviews. TRIAL REGISTRATION NUMBER: NCT05868291.

Usability and feasibility of an online intervention for older adults to support changes to routines and the home ('Light, activity and sleep in my daily life').

BACKGROUND: Indoor lighting, exposure to outdoor daylight, physical activity and sleep interact to influence functioning, mood and cicadian rhythm. Older adults (≥ 65 years), who often spend more time at home, are less physically active and experience more sleep problems, could benefit from strategies to support behavioural change and self-managed modifications in the home. The study's primary objective was to assess the usability and feasibility of the 'Light, activity and sleep in my daily life' intervention, delivered as a web-based course. METHODS: This 9-week intervention was delivered in a municipality in Sweden (55.70° N). Participants were eight healthy women (age 71-84), community-living in one-person households. We recruited through municipal staff and posters at senior citizen meeting points. Both qualitative and quantitative data were collected before and after the intervention. The outcome measures were intervention usability (ease of use, usefulness) and study feasibility (e.g., recruitment procedure, online engagement). Measures also included changes to routines and self-managed home adjustments to determine whether the participants applied what they had learnt. RESULTS: All participants completed the intervention. Time logged in varied between 25 min and 3 h (M = 1 h 50 min) per week. Seven participants' system usability scores were between 90 and 100 ('Excellent') out of 100. When interviewed, participants reported overall high satisfaction with what they had learnt. Six participants were particularly satisfied with the modules targeting light. Seven participants made changes to their lighting or darkness conditions, such as replaced bulbs with either 3-step dimming or higher colour temperature LEDs (samples were included in the intervention test kit). One suggestion to improve the online delivery was to enable participants to add text comments to the weekly evaluation form. CONCLUSIONS: The web-based intervention was feasible to deliver but time for recruitment should be extended and advertisement in the local newspaper should be considered. Participants' computer proficiency and access to the internet at home will be critical in a future study with a larger sample. Only minor changes to the online content of the intervention are needed based on participants' feedback. The intervention will be possible to evaluate in a future pilot study.

A biologically transparent illumination device is more useful in children for detecting the position of the nasogastric tube in the stomach.

PURPOSE: The study aimed to evaluate the efficacy of the Biologically Transparent Illumination (BTI) device for confirming the correct placement of nasogastric (NG) tubes in children, as an alternative to X-ray, which exposes patients to radiation. METHODS: In this prospective observational study, 106 pediatric patients (ages 0-16) undergoing NG-tube insertion after general anesthesia were evaluated. The BTI catheter was used to emit bio-permeable red light from the NG tube, which was then visually confirmed in the cervical, thoracic, and epigastric regions. X-ray confirmed NG-tube placement in all patients. The ethics committee approved the study. RESULTS: The average patient age was 3.8 years, with a male-to-female ratio of 72:34. BTI was successfully detected in the epigastric area in 105 of 106 patients, with one 9-year-old patient having unclear BTI visibility. X-ray confirmed NG-tube placement in the stomach for all patients, resulting in a BTI sensitivity of 99%. The mean NG-tube insertion time was 38 s, and the mean abdominal thickness was 9.8 mm. CONCLUSIONS: The BTI device proved to be a safe and effective method for NG-tube placement in children, offering a radiation-free alternative with 100% successful placement when BTI was detected in the epigastric area.

The effect of central and peripheral luminance on visual acuity.

CONTEXT: Lighting conditions significantly influence visual acuity (VA), visual function, and quality of life. Previous research highlighted a correlation between luminance and VA but left a gap in understanding the impact of surrounding luminance. This study focused on investigating the effects of both central and peripheral luminance on VA. PURPOSE: This study aimed to investigate the influence of both central and surrounding luminance on VA through distance VA measurements. SETTINGS AND DESIGN: A dual-component lighting system was utilized, comprising a self-illuminated ETDRS chart and a skyLED system for consistent surrounding illumination. Two experimental setups were conducted: the first varied the central luminance (25 ± 2-341 ± 10 cd/m²), while the second maintained a constant central luminance (150 ± 5 cd/m²) and varied the surrounding luminance (4 ± 2 cd/m² OFF-105 ± 10 cd/m² ON). METHODS: Sixty-six participants with refractive errors between 0.0 D and -2.75 D were tested under various lighting conditions. Both uncorrected refractive error (URE) and corrected refractive error (CRE) eyes were evaluated. STATISTICAL ANALYSIS USED: Paired t-tests were used to evaluate the statistical significance of differences in VA scores. RESULTS: Experiment 1 demonstrated a significant increase in VA scores, with mean improvements of -0.120 LogMAR for URE eyes and -0.073 LogMAR for CRE eyes as chart luminance increased from 26 cd/m² to 153 cd/m². Experiment 2 further showed a notable improvement in VA scores under varied surrounding luminance conditions, with mean improvements of - 0.118 LogMAR for URE eyes and -0.073 LogMAR for CRE eyes as luminance increased from 4 cd/m² to 102 cd/m². CONCLUSIONS: This study emphasizes the significant impact of both central and peripheral luminance on VA. The introduction of the skyLED lighting system underlines the importance of optimal lighting for visual performance.

Phosphor Screens Color Preferences Depending on Night Vision Experience and Luminance Level.

INTRODUCTION: One of the most important factors affecting visual performance during vision aided by night vision goggles (NVGs) is image quality, which depends mainly on the image-intensifier technology used. Although NVGs with green image color (P43 phosphor) are only accepted in military aviation, white image (P45 phosphor) seems to be equally well-regarded by aviators. The aim of our study was to determine if the experience of using NVGs with the green screen affects image preference for that color, and if the screen color preference is related to luminance level. METHODS: Subjects (127 military pilots, 26-56 yr, M = 37.2; 62 pilots with flight experience with NVG use) were asked to observe a model terrain board at two different luminance levels (corresponding roughly to ambient conditions during starlight and one-half moonlight) while using two types of NVGs (green P43 and white P45 phosphor screens). The pilots were asked to answer a questionnaire about their preference for NVG display color. RESULTS: The findings showed a significant difference between screen color preference and pilots' experience with the green-phosphor-based NVGs (43.5% vs. 23.1% for white screens). However, there was no relationship between screen color preference and luminance level. DISCUSSION: Previous NVG experience seems to play an important role in shaping a user's individual preference for a certain phosphor screen color, although green and white phosphor screens both provide satisfactory visibility. Nevertheless, when deciding, it is advisable to experiment with both colors and select the one that suits the user's preferences and needs. Lewkowicz R, Deren-Szumelda J. Phosphor screens color preferences depending on night vision experience and luminance level. Aerosp Med Hum Perform. 2024; 95(10):749-757.

Effect of Dopant Concentration on Luminescence Properties of Na3Ca2(SO4)3F: RE (RE = Eu3+, Dy3+) Phosphor for Solid-State Lighting.

A fluoride material phosphor doped with rare earth ions Eu3+ and Dy3+ was studied for its photoluminescence (PL) properties. The material was synthesized using a combustion method and characterized using X-ray diffraction (XRD) and PL techniques. The Na3Ca2(SO4)3F: Eu3+ phosphor exhibits two distinct peaks at 593 nm (orange) and 615 nm (red) at an excitation wavelength of 395 nm. The PL excitation spectrum of the Na3Ca2(SO4)3F: Dy3+ phosphor showed series of peaks, corresponding to the 4f → 4f transitions of Dy3+ ions. Under 350-nm excitation, the PL emission spectrum revealed two prominent bands one at 483 nm (blue region) due to the 4F9/2 → 6H15/2 transition, and another at 573 nm (yellow region) resulting from the 4F9/2 → 6H13/2 transition. These blue and yellow emissions suggest potential applications in solid-state lighting, particularly for mercury-free excitation sources. Rare earth-doped Eu3+/Dy3+ materials exhibit highly efficient PL properties, making them suitable candidates for white light-emitting diodes (LEDs) or other solid-state lighting phosphors.

Artificial light at night reveals hotspots and rapid development of industrial activity in the Arctic.

Climate warming enables easier access and operation in the Arctic, fostering industrial and urban development. However, there is no comprehensive pan-Arctic overview of industrial and urban development, which is crucial for the planning of sustainable development of the region. In this study, we utilize satellite-derived artificial light at night (ALAN) data to quantify the hotspots and the development of light-emitting human activity across the Arctic from 1992 to 2013. We find that out of 16.4 million km2 analyzed a total area of 839,710 km2 (5.14%) is lit by human activity with an annual increase of 4.8%. The European Arctic and the oil and gas extraction regions in Russia and Alaska are hotspots of ALAN with up to a third of the land area lit, while the Canadian Arctic remains dark to a large extent. On average, only 15% of lit area in the Arctic contains human settlement, indicating that artificial light is largely attributable to industrial human activity. With this study, we provide a standardized approach to spatially assess human industrial activity across the Arctic, independent from economic data. Our results provide a crucial baseline for sustainable development and conservation planning across the highly vulnerable Arctic region.

Investigation of a Camera-Based Contactless Pulse Oximeter with Time-Division Multiplex Illumination Applied on Piglets for Neonatological Applications.

(1) Objective: This study aims to lay a foundation for noncontact intensive care monitoring of premature babies. (2) Methods: Arterial oxygen saturation and heart rate were measured using a monochrome camera and time-division multiplex controlled lighting at three different wavelengths (660 nm, 810 nm and 940 nm) on a piglet model. (3) Results: Using this camera system and our newly designed algorithm for further analysis, the detection of a heartbeat and the calculation of oxygen saturation were evaluated. In motionless individuals, heartbeat and respiration were separated clearly during light breathing and with only minor intervention. In this case, the mean difference between noncontact and contact saturation measurements was 0.7% (RMSE = 3.8%, MAE = 2.93%). (4) Conclusions: The new sensor was proven effective under ideal animal experimental conditions. The results allow a systematic improvement for the further development of contactless vital sign monitoring systems. The results presented here are a major step towards the development of an incubator with noncontact sensor systems for use in the neonatal intensive care unit.

Artificial intelligence can regulate light and climate systems to reduce energy use in plant factories and support sustainable food production.

Plant factories with artificial lighting (PFALs) can boost food production per unit area but require resources such as carbon dioxide and energy to maintain optimal plant growth conditions. Here we use computational modelling and artificial intelligence (AI) to examine plant-environment interactions across ten diverse global locations with distinct climates. AI reduces energy use by optimizing lighting and climate regulation systems, with energy use in PFALs ranging from 6.42 kWh kg-1 in cooler climates to 7.26 kWh kg-1 in warmer climates, compared to 9.5-10.5 kWh kg-1 in PFALs using existing, non-AI-based technology. Outdoor temperatures between 0 °C and 25 °C favour ventilation-related energy use reduction, with outdoor humidity showing no clear pattern or effect on energy use. Ventilation-related energy savings negatively impact other resource utilization such as carbon dioxide use. AI can substantially enhance energy savings in PFALs and support sustainable food production.

The impacts of artificial light at night (ALAN) spectral composition on key behavioral traits of a sandy beach isopod.

Artificial light at night (ALAN) is a widespread human-induced disturbance, whose effects have been documented in many ecosystems. However, limited attention has been given to the source of the lights behind ALAN, so this study examined three of them: High-Pressure Sodium (HPS) lamps and warm and cool white Light-Emitting Diodes (LEDs). Laboratory experiments compared the effects of each type of light to natural day/night conditions, upon the activity, feeding behavior and growth of the isopod Tylos spinulosus. Tanks equipped with actographs monitored locomotor activity, while separate tanks were utilized to assess food consumption and growth under natural and ALAN conditions. Our results show that all ALAN sources disrupt and reduce isopods' activity and feeding behavior, with cool and warm LEDs being the most severe and mildest, respectively. Instead, ALAN had only minor effects on isopod growth. Our findings suggest that warm LEDs may be preferable for ALAN mitigation purposes.

Artificial Light at Night and Type 2 Diabetes Mellitus.

The widespread and pervasive use of artificial light at night (ALAN) in our modern 24-hour society has emerged as a substantial disruptor of natural circadian rhythms, potentially leading to a rise in unhealthy lifestyle-related behaviors (e.g., poor sleep; shift work). This phenomenon has been associated with an increased risk of type 2 diabetes mellitus (T2DM), which is a pressing global public health concern. However, to date, reviews summarizing associations between ALAN and T2DM have primarily focused on the limited characteristics of exposure (e.g., intensity) to ALAN. This literature review extends beyond prior reviews by consolidating recent studies from 2000 to 2024 regarding associations between both indoor and outdoor ALAN exposure and the incidence or prevalence of T2DM. We also described potential biological mechanisms through which ALAN modulates glucose metabolism. Furthermore, we outlined knowledge gaps and investigated how various ALAN characteristics beyond only light intensity (including light type, timing, duration, wavelength, and individual sensitivity) influence T2DM risk. Recognizing the detrimental impact of ALAN on sleep health and the behavioral correlates of physical activity and dietary patterns, we additionally summarized studies investigating the potential mediating role of each component in the relationship between ALAN and glucose metabolism. Lastly, we proposed implications of chronotherapies and chrononutrition for diabetes management in the context of ALAN exposure.

Moving Toward Evidence-Based Care: Measuring Preferences in Zoo-Housed Aquatic Turtles Using 24-h Remote Monitoring.

Providing evidence-based care to animals is a common goal in zoos and aquariums. However, there are many understudied species with a lack of information available, which may result in suboptimal care for individuals of these species. Using preference tests to ask individual animals what they want can be an effective means to enhance their care, and subsequently, their welfare. Using 24-h remote monitoring, we assessed substrate, enclosure feature, and lighting preferences of five aquatic turtles (two wood turtles, one Blanding's turtle, and two spotted turtles) that share an indoor enclosure at Lincoln Park Zoo. In addition, we compared enclosure feature and lighting preferences between winter and summer to determine whether the turtles had changing seasonal preferences despite being housed indoors. We found that the wood turtles and Blanding's turtle had substrate preferences, whereas the spotted turtles did not. In addition, we found that the turtles' enclosure feature preferences were consistent between winter and summer, but the amount of time spent on land, logs, and in water varied by individual. Finally, we found that the turtles utilized areas with ambient lighting more than areas with a heat lamp or UV lamp; this was consistent between winter and summer. The turtle preferences observed in this study can contribute to the development of care strategies that support their welfare and, in turn, may inspire similar preference studies at other institutions as we collectively advance toward providing animals of all taxonomic groups with evidence-based care.