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1. An Extended Analysis on the Benefits of Dark Mode User Interfaces in Optical See-Through Head-Mounted Displays

   https://doi.org/10.1145/3456874  

   Erickson, Austin ; Kim, Kangsoo ; Lambert, Alexis ; Bruder, Gerd ; Browne, Michael P. ; Welch, Gregory F. ( May 2021 , ACM Transactions on Applied Perception)

   null (Ed.)

   Light-on-dark color schemes, so-called “Dark Mode,” are becoming more and more popular over a wide range of display technologies and application fields. Many people who have to look at computer screens for hours at a time, such as computer programmers and computer graphics artists, indicate a preference for switching colors on a computer screen from dark text on a light background to light text on a dark background due to perceived advantages related to visual comfort and acuity, specifically when working in low-light environments. In this article, we investigate the effects of dark mode color schemes in the field of optical see-through head-mounted displays (OST-HMDs), where the characteristic “additive” light model implies that bright graphics are visible but dark graphics are transparent . We describe two human-subject studies in which we evaluated a normal and inverted color mode in front of different physical backgrounds and different lighting conditions. Our results indicate that dark mode graphics displayed on the HoloLens have significant benefits for visual acuity and usability, while user preferences depend largely on the lighting in the physical environment. We discuss the implications of these effects on user interfaces and applications. 

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2. Adapting Michelson Contrast for use with Optical See-Through Displays

   https://doi.org/10.1109/ISMAR-Adjunct57072.2022.00088  

   Erickson, Austin ; Bruder, Gerd ; Welch, Gregory F. ( October 2022 , 2022 IEEE International Symposium on Mixed and Augmented Reality Adjunct (ISMAR-Adjunct))

   Due to the additive light model employed by current optical see-through head-mounted displays (OST-HMDs), the perceived contrast of displayed imagery is reduced with increased environment luminance, often to the point where it becomes difficult for the user to accurately distinguish the presence of visual imagery. While existing contrast models, such as Weber contrast and Michelson contrast, can be used to predict when the observer will experience difficulty distinguishing and interpreting stimuli on traditional dis-plays, these models must be adapted for use with additive displays. In this paper, we present a simplified model of luminance contrast for optical see-through displays derived from Michelson's contrast equation and demonstrate two applications of the model: informing design decisions involving the color of virtual imagery and optimizing environment light attenuation through the use of neutral density filters. 

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3. Effects of Optical See-Through Displays on Self-Avatar Appearance in Augmented Reality

   https://doi.org/10.1109/ISMAR-Adjunct57072.2022.00077  

   Doroodchi, Meelad ; Ramos, Priscilla ; Erickson, Austin ; Furuya, Hiroshi ; Benjamin, Juanita ; Bruder, Gerd ; Welch, Gregory F. ( October 2022 , Proc.of the IEEE International Symposium on Mixed and Augmented Reality (ISMAR) Workshop on Inclusion, Diversity, Equity, Accessibility, Transparency, and Ethics in XR (IDEATExR))

   Display technologies in the fields of virtual and augmented reality affect the appearance of human representations, such as avatars used in telepresence or entertainment applications, based on the user’s current viewing conditions. With changing viewing conditions, it is possible that the perceived appearance of one’s avatar changes in an unexpected or undesired manner, which may change user behavior towards these avatars and cause frustration in using the AR display. In this paper, we describe a user study (N=20) where participants saw themselves in a mirror standing next to their own avatar through use of a HoloLens 2 optical see-through head-mounted display. Participants were tasked to match their avatar’s appearance to their own under two environment lighting conditions (200 lux and 2,000 lux). Our results showed that the intensity of environment lighting had a significant effect on participants selected skin colors for their avatars, where participants with dark skin colors tended to make their avatar’s skin color lighter, nearly to the level of participants with light skin color. Further, in particular female participants made their avatar’s hair color darker for the lighter environment lighting condition. We discuss our results with a view on technological limitations and effects on the diversity of avatar representations on optical see-through displays. 

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4. Investigation of a real-time change of human eye pupil sizes per visual sensation condition

   Choi, Joon-Ho ; Lin, Xiaoxin ; Schiller, Marc ( May 2018 , ARCC - EAAE 2018 INTERNATIONAL CONFERENCE)

   Lighting is the most crucial factor impacting an occupants’ visual comfort in a building environment. However, most prevailing current lighting guidelines deriving from empirical values are designed primarily for paper-based tasks, rather than computer-based. In many cases, present guidelines have been reported that there is a limitation to meet the needs for a user’s new task types. Above all, existing technical tools also have a limited function to evaluate a user’s real-time visual perception which can be applied as an indicator to control a building lighting system. This research estimated each individual participant's visual sensations by analyzing pupil sizes and their change patterns since the human body have the physiological regulation ability which naturally minimizes the adverse effects of the surrounding environment on the human body. This study adopted a series of human subject experiments which were performed in an environmental chamber of USC. Based on a computer-based task which are most commonly performed in current offices, various ranges of ambient lighting parameters, including luminance (cd/m2), illuminance (lux), contrast ratio, and UGR, were generated and controlled while each subject’s pupil sizes were recorded. The experimental result data were statistically analyzed to identify a relationship between human visual sensations, lighting parameters, and also pupil sizes by ethnic origin and myopia condition. The research outcomes showed the potential use of pupil sizes for estimating an individual’s visual sensation, and confirmed the principle as an applicable technology to integrate an environmental design and control system with the help of a real-time sensing device. 

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5. M oon S hine : A software‐hardware system for simulating moonlight ground illuminance and re‐creating artificial moonlight cycles in a laboratory environment

   https://doi.org/10.1111/2041-210X.14299  

   Poon, Lok ; Jenks, Ian T. ; Crampton, W. G. R. ( February 2024 , Methods in Ecology and Evolution)

   Moonlight exerts profound ecological, behavioural and physiological effects on animals. However, lunar cycles are characterised by complex changes in the illuminance and timing of illumination, making it challenging to re‐create and manipulate moonlight cycles in the laboratory using artificial lights. As a result, ecological experiments on the effects of moonlight cycles are uncommon, and existing studies often oversimplify the re‐creation of moonlight. This limitation extends to experimental studies of the effects of light pollution on nocturnal animals, which often fail to adequately represent natural nocturnal light.

   To address the lack of open‐source solutions for re‐creating and manipulating moonlight cycles, we developed the software‐hardware systemMoonShine. This has two components: (1)MoonShineR, an R package with additional R scripts, which predicts moonlight ground illuminance (in lux) at defined intervals, for a specified location and time range; (2)MoonShineP, a Python program running on a Raspberry Pi computer, which uses the illuminance values fromMoonShineRto gradually dim and brighten a diffused array of individually addressable LEDs, allowing realistic natural light regimes to be re‐created in a laboratory environment.MoonShineincludes multiple features to re‐create and manipulate light cycles. It supports colour‐shifting of the LED light (by adjustment of RGBW intensity ratios) to approximate the spectrum of natural moonlight, and to mimic habitat‐specific conditions or certain types of light pollution.

   We tested the accuracy ofMoonShineR's moonlight illuminance predictions by comparison to field radiometer measurements at equatorial and temperate latitude sites. We demonstrated the accuracy ofMoonShineP's moonlight re‐creation, by comparing its measured LED illuminances to the intended values and its measured LED spectrum against natural moonlight.

   MoonShineallows researchers to re‐create a range of natural nocturnal lighting scenarios in the laboratory. It can be used to re‐create full natural moonlight cycles with a relatively realistic spectral composition, generate manipulated moonlight schedules, or simulate light pollution. Furthermore, the moonlight illuminance predicted byMoonShineRis useful for field ecologists who require moonlight as a quantitative model predictor. Finally, to provide laboratory‐housed animals with full diurnal light cycles,MoonShineallows researchers to re‐create natural twilight and sunlight regimes.

    

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