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Differentiable rendering methods promise the ability to optimize various parameters of three-dimensional (3D) scenes to achieve a desired result. However, lighting design has so far received little attention in this field. In this article, we introduce a method that enables continuous optimization of the arrangement of luminaires in a 3D scene via differentiable light tracing. Our experiments show two major issues when attempting to apply existing methods from differentiable path tracing to this problem: First, many rendering methods produce images, which restricts the ability of a designer to define lighting objectives to image space. Second, most previous methods are designed for scene geometry or material optimization and have not been extensively tested for the case of optimizing light sources. Currently available differentiable ray-tracing methods do not provide satisfactory performance, even on fairly basic test cases in our experience. In this article, we propose, to the best of our knowledge, a novel adjoint light tracing method that overcomes these challenges and enables gradient-based lighting design optimization in a view-independent (camera-free) way. Thus, we allow the user to paint illumination targets directly onto the 3D scene or use existing baked illumination data (e.g., light maps). Using modern ray-tracing hardware, we achieve interactive performance. We find light tracing advantageous over path tracing in this setting, as it naturally handles irregular geometry, resulting in less noise and improved optimization convergence. We compare our adjoint gradients to state-of-the-art image-based differentiable rendering methods. We also demonstrate that our gradient data works with various common optimization algorithms, providing good convergence behaviour. Qualitative comparisons with real-world scenes underline the practical applicability of our method. [ABSTRACT FROM AUTHOR]

Copyright of Cuadernos del Centro de Estudios de Diseño y Comunicación is the property of Cuadernos del Centro de Estudios de Diseno y Comunicacion and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The author considers her experience as the lighting designer for John Doyle's production of the Stephen Sondheim and John Weidman's musical Road Show at the Public Theater in New York City in 2008. She reflects on the experience of her life and career as an immigrant designer in the American theatre in relationship to the story of the musical, and relates her experience of the rehearsal and technical process of the production. The author considers her relationship to the American musical through the experience of designing this one particular Sondheim musical and explores various relationships to America, to the musical and to theatre in capitalism in the context of particular songs from the musical. [ABSTRACT FROM AUTHOR]

On the basis that an effective lighting design procedure should enable practitioners to reliably achieve positive responses from the people who will experience the lighting, the effectiveness of current practice is found lacking in that it is largely unrelated to peoples' responses. Additionally, the calculation procedures widely used for devising indoor lighting solutions require the user to propose a solution and for the procedure to determine its performance. It is argued that a truly effective procedure would require the practitioner to describe lighting design objectives for the application, and for the procedure to derive the performance specification of a lighting scheme that would achieve the objectives. Evidence of changing attitudes among lighting professionals is identified, which together with recent research findings, has led to a proposal for reassessment of the purpose for which indoor lighting is provided based on peoples' responses. The Lighting Design Objectives (LiDOs) Procedure is gaining use among professional lighting designers and is used to illustrate practical application of this notion. The implications of such a procedure becoming generally adopted for indoor lighting practice are discussed. [ABSTRACT FROM AUTHOR]

This article presents the method of implementation and the results of experimental investigations illustrating an influence of parameters of the signal controlling the current flowing through power LEDs on their junction temperature and on parameters characterizing the light emitted by them. The measurement system used and the tested power LEDs are described. The results of measurements of the junction temperature of the tested devices, the values of the average value of the power dissipated in the tested devices and the photometric and radiometric parameters of these devices obtained for different values of frequency and the duty cycle of the signal controlling the current flowing through the tested diodes are presented and discussed. It is shown that the operation of the considered semiconductor devices is more effective at low frequency values. The possibility of adjusting the optical parameters of the power LEDs in the considered range of frequency and the duty cycle adjustment is assessed. Additionally, the measured waveforms of the current supplying the tested LEDs is shown. The influence of the parasitic capacitances of the tested devices is discussed. On the basis of the obtained investigation results, some recommendations for the designers of lighting systems can be formulated. In order to obtain an almost linear dependence of the illuminance on the duty cycle, the values of frequency not exceeding 10 kHz should be used. [ABSTRACT FROM AUTHOR]

Indoor lighting, incorporated with visual and circadian needs, is the upcoming goal of lighting designers. In tropical and subtropical regions, where more daylight is available, daylight harvesting is a prime source of ambient lighting indoors. This paper aims to study various cases of lighting ambience to investigate the circadian lighting capability in terms of the circadian stimulus (CS) of the system under consideration. The instances considered are simulation studies in an open office plan and real-time experimentations in a test workbench and a faculty cabin. Daylight integration was undertaken through controlled venetian blinds, tunable sources and a commercially available human-centric lighting system. The result and analysis show the influence of spectrally tunable light sources on CS rather than fixed light sources. Due to the varying CCT of tunable LED luminaire, circadian stimulation for an occupant can be easily incorporated without crossing the limits of vertical and horizontal illuminance, which may lead to visual discomfort. The findings from this study reveal that daylight–artificial light integration scheme with controlled shading and spectrally tunable source provides the optimal solution for glare-free, energy-effective and circadian entrainment, i.e. human-centric lighting (HCL). With the help of simulations, pre-evaluation will aid the lighting engineers in making a better choice among the various lighting-controlled schemes to implement HCL in indoor office spaces. [ABSTRACT FROM AUTHOR]

We introduce a lighting technology designed to produce photoreceptor-directed lights (PrD). This photoreceptor-enhanced light therapy (PELT) differs from conventional supplemental lighting by using multiple limited-bandwidth primaries to generate spectra that appear white, and that are tailored to produce circadian equivalent (CE) lights for selectively increasing or decreasing the relative activation levels of specific photoreceptor classes in the human eye. Rather than designing a device to match a spectrum's shape, we optimize the available hardware, so it best matches the biological effects of that spectrum. It goes beyond three and four dimensions (three cones plus melanopsin) to consider the biological responses mediated via all five photoreceptor classes (including rhodopsin); the inclusion of a fifth photoreceptor class is non-trivial both in implementation and biological effect. Here, we describe the technical specifications of the PELT device and its calibration procedures. Photoreceptor-directed lights with variable melanopsin and rhodopsin excitations and equal photometric luminance are presented. Device application examples are provided that include personalized supplemental light spectra for patients with photoreceptor sensitivity loss, for healthy people exposed to extreme seasonal or work-related variation in their ambient lighting patterns, and as a stimulus generator to evaluate the effects of light on human health and behavior mediated via the melanopsin expressing intrinsically photosensitive retinal ganglion cells (ipRGCs). In integrative lighting practice, the PELT method extends to dynamic control of the biological potency of the melanopsin and rhodopsin excitations over a large range, independent of perceived changes in correlated color temperature (CCT). [ABSTRACT FROM AUTHOR]

• CCT values did not correlate linearly with visual perception. • Lighting professionals can not recognize CCT accurately. • CCT recognition errors influenced colour rendition of indoor lighting. • Absolute and global lighting quality metrics should be recommended. Correlated Colour Temperature (CCT) is a crucial parameter for white light sources and it is closely related to the colour rendition quality of indoor lighting. In this study, two psychophysical experiments were conducted to examine the CCT recognition error of human observers and then investigate the relevant influence on the qualification of colour rendition quality. In Experiment 1, 36 lighting designers were invited to participate in a CCT recognition test with CCT values ranging from 3000 K to 6000 K, by which we obtained their recognition errors and discriminable intervals. It was found that even lighting professionals cannot recognize the CCT value very accurately and that CCT did not correlate linearly with visual perception. In Experiment 2, we further explored the influence of lighting designers' CCT recognition errors on colour preference and discrimination judgements toward 8 kinds of objects with 50 naïve subjects by constructing a typical indoor lighting scenario. It was found that due to the CCT recognition errors revealed in Experiment 1, even professional lighting designers could hardly select the most appropriate CCT for a specific lighting scenario in terms of colour preference and colour discrimination. We hope those findings could provide a deeper understanding for the concepts of CCT and colour rendition of indoor lighting. As we believe, for quantifying the visual attributes like colour preference and discrimination, an absolute and global metric whose calculation protocol is independent of CCT value should be advocated. [ABSTRACT FROM AUTHOR]

In the last decade, the extensive introduction of LED lighting sources has brought elements of innovation to interior lighting design in terms of color. Besides the new tunable white LED source, lighting is no longer exclusively white; indeed, colored lighting has entered the design practice thanks to the positive effects on people's health and mood. Unfortunately, this element of lighting innovation, color, cannot be computed correctly in commercial lighting design software. These computations are based on the assumption that light is only white or defined in terms of RGB triplets in the relative digital color space of computer graphics, which does not have a physically correct relationship with the actual spectral power distribution (SPD) of luminaires. In this paper, attention is focused on a practical design‐oriented approach for describing luminaires in lighting design software that also considers the real SPD and the luminous intensity distribution. The focus is on information available to lighting designers who do not have a laboratory to measure light sources and luminaires. This information could be available in online datasheets or as a Cartesian graph from luminaires and light sources manufacturers. Following this approach, a set of functions is proposed that can be easily implemented in lighting design software to improve light sources' color management and allow lighting designers to add SPD data to luminaires. [ABSTRACT FROM AUTHOR]

The advancement of LED and controls technology, computing capacity, and software provides new opportunities for researchers and designers to work together to further optimize spaces for occupant benefit. Lighting system control data from five neonatal intensive care unit patient rooms was collected over a 25-week monitoring period and analyzed to better understand occupant response to a tunable lighting system with automatic transitions throughout the day. Lighting systems are very rarely refined after installation based on actual use. Objective data detailing how the lighting system is used by the actual occupants highlights the opportunities for optimization after installation and provides insight for improving the next design. As use of the data becomes more commonplace, it can be leveraged for design recommendations. The collection of the data required no additional cost beyond the time for examining the data. The analysis revealed several clear opportunities for improvement, including adjustments to the default control setting at night, re-labeling of the control stations, and adjustments to the nighttime fade rate. The patient room occupants were active users of the different zones, dimming options, and manual overrides made available by the lighting system. [ABSTRACT FROM AUTHOR]

Purpose: Good illumination creates an aesthetic environment that may positively influence patients' well-being and provide comfort to the hospital staff. This study aims to focus on exploring the energy efficiency of lighting and subjective perception of the lit environment in a hospital ward to assess quality indicators of ambient lighting conditions. Design/methodology/approach: The existing conventional tubular fluorescent lamp–based lighting system in the surveyed patients' ward was retrofitted with light-emitting diode (LED) luminaires to explore illumination and energy parameters. Thereafter, a software lighting model was created, simulated and analyzed. A Web-based survey with five bipolar adjective pairs in a semantic differential scale was conducted with 48 participants to record and analyze their subjective responses pertaining to the variations in lamp types and surface reflectance combinations. Findings: The findings imply that the LED tubular lamp–based illumination was deemed more adequate compared to other lamp types and the effects of variations in room surface reflectance combinations on the participants' responses were statistically significant at α = 0.05 level. The simulated horizontal work plane average illuminance level varied from 131 to 171 lx, mean room surface exitance (MRSE) levels remained between 30 and 90 lm/m2 and overall uniformity of illuminance remained between 0.5 and 0.7. Originality/value: In a hospital ward illuminated by LED tubular lamps, variations in room surface reflectance combinations for a constant luminous flux package output from the lamps may affect the subjective perception of users and the correlation between horizontal work plane average illuminance and MRSE is found to be highly linear (coefficient of determination > 0.97). [ABSTRACT FROM AUTHOR]

Featured Application: This article is intended for the professionals in the area of roadway lighting, particularly for roadway lighting designers. The main goal of roadway lighting design is ensuring compliance with mandatory lighting standards and thus increasing safety for all road users. On the other hand, a design process being only a part of a road investment has to be completed in possibly a short time, due to business needs. The commonly used method for reconciling both requirements is using predefined lighting projects (templates) which are matched with similar, real-life lighting situations. This approach works well for a typical roadway lighting design but not necessarily for crosswalk illumination due to different specifics of underlying calculations (they focus on the contrast of a pedestrian against its background rather than roadway illumination). As one deals with pedestrian safety here, we decided to perform extensive tests to find out whether a standard compliant lighting project prepared for a given crosswalk can be safely applied (in terms of preserving standard compliance) to another similar crosswalk. To accomplish that, we investigated nearly 900 million situations obtained as modifications of the reference template. Results proved that even a 5% change of layout sizes (crosswalk width, lamp spacing, pole height etc.) makes 40% of obtained projects violate illumination requirements. The conclusion of this result is that the template-based design approach broadly used for roadway lighting cannot be applied for pedestrian crossings as it may cause serious safety issues. [ABSTRACT FROM AUTHOR]

Copyright of Cuadernos del Centro de Estudios de Diseño y Comunicación is the property of Cuadernos del Centro de Estudios de Diseno y Comunicacion and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Cuadernos del Centro de Estudios de Diseño y Comunicación is the property of Cuadernos del Centro de Estudios de Diseno y Comunicacion and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: Maintaining a motivated health workforce is critical to health system effectiveness and quality of care. Scant evidence exists on whether interventions aimed to strengthen health infrastructure in low-resource settings affect health workers. This study evaluated the impact of an intervention providing solar light and electricity to rural maternity facilities in Uganda on health workers' job satisfaction.Methods: We used a mixed-methods design embedded in a cluster randomized trial to evaluate whether and how the We Care Solar Suitcase intervention, a solar electric system providing lighting and power, affected health workers in rural Ugandan maternity facilities with unreliable light. Facilities were randomly assigned to receive the intervention or not without blinding in a cluster-randomized controlled trial. Outcomes were assessed through two rounds of surveys with health workers. We used regression analyses to examine the intervention's impact on job satisfaction. We used an inductive approach to analyze qualitative data to understand the study context and interpret quantitative findings.Results: We interviewed 85 health workers across 30 facilities, the majority of whom were midwives or nurses. Qualitative reports indicated that unreliable light made it difficult to provide care, worsened facility conditions, and harmed health workers and patients. Before the intervention, only 4% of health workers were satisfied with their access to light and electricity. After the installation, satisfaction with light increased by 76 percentage points [95% confidence interval (CI): 61-92 percentage points], although satisfaction with electricity did not change. Experience of negative impacts of lack of overhead light also significantly decreased and the intervention modestly increased job satisfaction. Qualitative evidence illustrated how the intervention may have strengthened health workers' sense of job security and confidence in providing high-quality care while pointing towards implementation challenges and other barriers health workers faced.Conclusions: Reliable access to light and electricity directly affects health workers' ability to provide maternal and neonatal care and modestly improves job satisfaction. Policy makers should invest in health infrastructure as part of multifaceted policy strategies to strengthen human resources for health and to improve maternal and newborn health services. Trial registration socialscienceregistry.org: AEARCTR-0003078. Registered June 12, 2018, https://www.socialscienceregistry.org/trials/3078 Additionally registered on: ClinicalTrials.gov: NCT03589625, Registered July 18, 2018, https://clinicaltrials.gov/ct2/show/NCT03589625 ). [ABSTRACT FROM AUTHOR]

Designers desire to sketch their concepts and produce prototypes in a real-time setting. This study developed a virtual reality (VR) supported lighting sketch tool for vehicle interior designers. The tool incorporated lighting design with drag-and-drop functionality and high-definition vehicle rendering. The tool also used the Wizard-of-Oz method to help design participants easily immerse themselves into the design tasks. Six designers participated in two consecutive hour-long design workshops to evaluate the design tool. Each designer sketched eight scenarios, and the workshop gathered 48 design outcomes. In addition, a thirty-minute post-interview evaluated usability, the immersive experience of the virtual environment, and the expected role of the wizard. Finally, thematic coding was used on both workshop and post-interview verbal records to further evaluate the tool's compatibility. As a result, three vital roles of the tool were identified. First, the tool encouraged the iteration process. The tool also gave realistic design-practice experiences and would be suitable for sketching lighting in the workplace. Finally, the tool allowed designers to immerse themselves in the design space. This research anticipates a well-illustrated virtual context and situations that invite designers into an inspirational lighting design workplace. [ABSTRACT FROM AUTHOR]

This paper proposes tridimensional (3D) laser scanning to architects and lighting designers as a lighting enquiry and visualization method for existing built environments. The method constitutes a complement to existing lighting methods by responding to limitations of photometric measurements, computer simulation and HDR imagery in surveying and visualizing light in actual buildings. The research explores advantages and limitations of 3D laser scanning in a case study addressing a vast, geometrically complex and fragmented naturally and artificially lit space. Lighting patterns and geometry of the case study are captured with a 3D laser scanner through a series of four scans. A single 3D model of the entire space is produced from the aligned and fused scans. Lighting distribution patterns are showcased in relation to the materiality, geometry and position of windows, walls, lighting fixtures and day lighting sources. The point cloud model of the case study is also generated into a video format representing the entire building as well as different viewpoints. The study shows that the proposed method provides powerful visualization results due to the unlimited number of images that can be generated from a point cloud and facilitates understanding of existing lighting conditions in spaces. [ABSTRACT FROM AUTHOR]

As the Prague Quadrennial of Performance Design and Space 2019 (PQ19) drew to a close, Australian designers, researchers and educators gathered to discuss the impact of PQ on our scenographic communities while querying the evolutions and challenges facing design practice. Australia's vast geography made this event a unique opportunity to bring together leading experts from multiple states and capture contemporary perspectives. At the midpoint between the 2019 and 2023 gatherings – a time of global pandemics, political unrest and educational transformation – this article offers the outcomes of this roundtable as a unique snapshot of the state of design practice within Australia through the lens of the Quadrennial. The roundtable was themed around Australia's presence at PQ19, the effects of PQ19 on those present and the ripples to be felt by those at home, and what attendance illuminated about current developments and concerns in practice, teaching and research. Led by practitioner-researchers Tessa Rixon and Madeline Taylor, the roundtable featured both the curators of Australia's country and student exhibits; award-winning set, costume and lighting designers with diverse experiences from national opera to independent theatre; and educators and researchers from the nation's top universities. The resulting discussion presents a unique perspective on the gaps and weaknesses in the design education, practice and research; first-hand insights on the challenges and opportunities available in both exhibiting and participating in the PQ; and the need to actively promote and privilege diverse voices and a multiplicity of representations in the process of claiming a 'national' scenographic identity. The roundtable was the first to capture multiple expert first-person Australian perspectives on the PQ while simultaneously contributing to the ongoing international discussion of performance design through the lens of artists, educators and researchers. [ABSTRACT FROM AUTHOR]