Category: Research

New Research Proposes A Framework For Window View Quality Within Buildings

A team of researchers have recently published new research on window views from within buildings and have proposed a new framework for designing “view quality” for window views.  The team identified three critical factors in determining view quality.

A team of researchers have recently published new research on window views from within buildings and have proposed a new framework for designing “view quality” for window views.  The team identified three critical factors in determining view quality.

  1. View Content – what’s seen through the window
  2. View Access – how much window view the occupant’s position has
  3. View Clarity – how clearly the view content can be seen

The research team propose an index for window view quality, along with design recommendations.  The full paper can be accessed here.  The paper was also published online by Leukos on 11/10/21.  The researchers are from:

  • The Center for the Built Environment, UC Berkeley
  • Berkeley Education Alliance for Research in Singapore
  • Loisos + Ubbelohde
  • California College of the Arts

#windowviews

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Recommended Methods for Subjective Evaluation of Color Rendition

A new study funded by the Department of Energy and published in Lighting Research and Technology reviews the commonly used psychophysical experimental techniques for investigating color rendition, where human participants are asked to evaluate various subjective aspects of the color appearance of objects, such as color preference, naturalness, or vividness.

Color rendition describes the influence of light source spectrum on the color appearance of objects. The rendering of object colors in desirable ways has attracted much attention as LEDs have developed as a versatile and efficient lighting technology, with significant research effort to understand human perception and develop new metrics. These have helped manufacturers optimize LED lighting products, increasing both energy efficiency and appeal to drive adoption in workplaces and homes.

Spectrally tunable LED-based lighting is one large and growing segment of emerging products, which has also facilitated new experimental techniques. However, the increased interest and ease of experimentation has not necessarily translated into improved research quality, a more diverse range of experiments, more definitive findings, or increased use of efficient, high-quality LED products. Instead, the collective body of work has sometimes employed questionable methods that produce contradictory and, at times, overgeneralized results.

A new study funded by the Department of Energy and published in Lighting Research and Technology reviews the commonly used psychophysical experimental techniques for investigating color rendition, where human participants are asked to evaluate various subjective aspects of the color appearance of objects, such as color preference, naturalness, or vividness. The work was undertaken to encourage exceptional practices in the conceptualization, design, implementation, analysis, and reporting of such experiments. It is intended to accelerate research progress and the resulting improvements in lighting quality and energy efficiency.

The article synthesizes a large body of evidence on research methods, tailoring the solutions to the specific field using examples. Common pitfalls of existing color rendition research include a lack of clear hypotheses, failing to control for all lighting variables, insufficient adaptation, poor sampling of possible color rendition characteristics, and small sample sizes with insufficient statistical rigor. The study outlines a range of possible work to improve future methods and concludes with a list of recommended practices relevant to performing research on subjective evaluations of color rendition, which may be used as checklist by researchers, reviewers, and readers.

According to Dr. Yoshi Ohno, NIST Fellow at the National Institute of Standards and Technology, who was not involved in this study, there is still much room to improve the color quality of white LED sources for lighting preferences in different applications while ensuring the best use of energy. “Vision experiments are essential to make progress in research for this effort,” he says, “and this article by PNNL covers the whole range of important topics and recommendations for designing and conducting such vision experiments with subjects. It will be very useful for all researchers working in this area toward establishing good recommendations on color quality of LED sources for lighting.”

Download the full report.

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MIT Engineers Use Nanoparticles to Create Rechargeable Light-Emitting Plants

Using specialized nanoparticles embedded in plant leaves, MIT engineers have created a light-emitting plant that can be charged by an LED. After 10 seconds of charging, plants glow brightly for several minutes, and they can be recharged repeatedly.

Using specialized nanoparticles embedded in plant leaves, MIT engineers have created a light-emitting plant that can be charged by an LED. After 10 seconds of charging, plants glow brightly for several minutes, and they can be recharged repeatedly.

These plants can produce light that is 10 times brighter than the first generation of glowing plants that the research group reported in 2017.

“We wanted to create a light-emitting plant with particles that will absorb light, store some of it, and emit it gradually,” says Michael Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT and the senior author of the new study. “This is a big step toward plant-based lighting.”

“Creating ambient light with the renewable chemical energy of living plants is a bold idea,” says Sheila Kennedy, a professor of architecture at MIT and an author of the paper who has worked with Strano’s group on plant-based lighting. “It represents a fundamental shift in how we think about living plants and electrical energy for lighting.”

The particles can also boost the light production of any other type of light-emitting plant, including those Strano’s lab originally developed. Those plants use nanoparticles containing the enzyme luciferase, which is found in fireflies, to produce light. The ability to mix and match functional nanoparticles inserted into a living plant to produce new functional properties is an example of the emerging field of “plant nanobionics.”

Pavlo Gordiichuk, a former MIT postdoc, is the lead author of the new paper, which appears in Science Advances.

Light capacitor

Strano’s lab has been working for several years in the new field of plant nanobionics, which aims to give plants novel features by embedding them with different types of nanoparticles. Their first generation of light-emitting plants contained nanoparticles that carry luciferase and luciferin, which work together to give fireflies their glow. Using these particles, the researchers generated watercress plants that could emit dim light, about one-thousandth the amount needed to read by, for a few hours.

In the new study, Strano and his colleagues wanted to create components that could extend the duration of the light and make it brighter. They came up with the idea of using a capacitor, which is a part of an electrical circuit that can store electricity and release it when needed. In the case of glowing plants, a light capacitor can be used to store light in the form of photons, then gradually release it over time.

To create their “light capacitor,” the researchers decided to use a type of material known as a phosphor. These materials can absorb either visible or ultraviolet light and then slowly release it as a phosphorescent glow. The researchers used a compound called strontium aluminate, which can be formed into nanoparticles, as their phosphor. Before embedding them in plants, the researchers coated the particles in silica, which protects the plant from damage.

The particles, which are several hundred nanometers in diameter, can be infused into the plants through the stomata — small pores located on the surfaces of leaves. The particles accumulate in a spongy layer called the mesophyll, where they form a thin film. A major conclusion of the new study is that the mesophyll of a living plant can be made to display these photonic particles without hurting the plant or sacrificing lighting properties, the researchers say.

This film can absorb photons either from sunlight or an LED. The researchers showed that after 10 seconds of blue LED exposure, their plants could emit light for about an hour. The light was brightest for the first five minutes and then gradually diminished. The plants can be continually recharged for at least two weeks, as the team demonstrated during an experimental exhibition at the Smithsonian Institute of Design in 2019.

“We need to have an intense light, delivered as one pulse for a few seconds, and that can charge it,” Gordiichuk says. “We also showed that we can use big lenses, such as a Fresnel lens, to transfer our amplified light a distance more than one meter. This is a good step toward creating lighting at a scale that people could use.”

“The Plant Properties exhibition at the Smithsonian demonstrated a future vision where lighting infrastructure from living plants is an integral part of the spaces where people work and live,” Kennedy says. “If living plants could be the starting point of advanced technology, plants might replace our current unsustainable urban electrical lighting grid for the mutual benefit of all plant-dependent species — including people.”

Large-scale illumination

The MIT researchers found that the “light capacitor” approach can work in many different plant species, including basil, watercress, and tobacco, the researchers found. They also showed that they could illuminate the leaves of a plant called the Thailand elephant ear, which can be more than a foot wide — a size that could make the plants useful as an outdoor lighting source.

The researchers also investigated whether the nanoparticles interfere with normal plant function. They found that over a 10-day period, the plants were able to photosynthesize normally and to evaporate water through their stomata. Once the experiments were over, the researchers were able to extract about 60 percent of the phosphors from plants and reuse them in another plant.

Researchers in Strano’s lab are now working on combining the phosphor light capacitor particles with the luciferase nanoparticles that they used in their 2017 study, in hopes that combining the two technologies will produce plants that can produce even brighter light, for longer periods of time.

The research was funded by Thailand Magnolia Quality Development Corp., a Professor Amar G. Bose Research Grant, MIT’s Advanced Undergraduate Research Opportunities Program, the Singapore Agency of Science, Research, and Technology, a Samsung scholarship, and a German Research Foundation research fellowship.

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RPI’s Bob Karlicek on Spatially Tunable Lighting

For an upcoming article in Electrical Contractor Magazine, I recently had the opportunity to interview Bob Karlicek, Ph.D., Professor of Electrical, Computer and Systems Engineering at Rensselaer Polytechnic Institute, Director of the Center for Lighting Enabled Systems and Applications, co-Director of the Energy, Built Environment and Smart Systems Institute at Rensselaer. The topic: spatially tunable lighting, which LightNOW first reported on in August. Transcript follows.

For an upcoming article in Electrical Contractor Magazine, I recently had the opportunity to interview Bob Karlicek, Ph.D., Professor of Electrical, Computer and Systems Engineering at Rensselaer Polytechnic Institute, Director of the Center for Lighting Enabled Systems and Applications, co-Director of the Energy, Built Environment and Smart Systems Institute at Rensselaer. The topic: spatially tunable lighting, which LightNOW first reported on here. Transcript follows.

DiLouie: What is spatially tunable lighting?

Karlicek: Spatially tunable lighting creates the ability to digitally alter the light emitting properties of a luminaire directionally and spectrally, to customize lighting profiles for given tasks. For example, imagine a troffer that could provide task lighting at a table, and then digitally adapt for more diffuse lighting for a meeting. Furthermore, the lighting system would know which tasks needed which lighting profiles, and digitally adjust the profile as needed.

DiLouie: What is the rationale behind its development? What is the market need, and what are the benefits?

Karlicek: The rationale is twofold: energy savings by providing only the right amount of illumination for a given occupancy scene, and lighting installation cost savings by installing a beam steerable light fixture that can deliver the beam profiles of two or more individual fixed profile light fixtures.

DiLouie: LESA is currently developing a solution with Lumileds, CASE, and HKS. What is the research goal?

Karlicek: The research goal of this DOE BTO funded project is to build a testbed to validate the energy savings and human factors considerations (circadian lighting, comfort with adaptive lighting) with a lighting system that can operate autonomously, sensing the occupant positions and estimating the type of activity, and then delivering only the required amount of illumination with the desired beam profile and spectral characteristics for the task at hand.

DiLouie: What’s different between this type of lighting solution and the most advanced solutions currently offered?

Karlicek: First and foremost, there aren’t many digitally steerable lighting solutions on the market and those that are use motors or have limited beam steering capability. Second, lighting control systems still suffer from “human in the loop” challenges. As tunable lighting for wellness gets more complicated, occupant control will require too much knowledge for mere mortals to be able to operate them properly. Our research testbed will explore delivering the “right light when and where needed,” where optimized lighting will require no occupant intervention.

DiLouie: If realized, SCULPT will present a “sentient” lighting system that is intuitively responsive to occupants without direct intervention. Is similar research being undertaken for other systems such as HVAC, which would allow a “sentient” building?

Karlicek: That would be the goal of this program, adding lighting to the list of building systems that operate autonomously. Even more importantly, the sensing systems needed for the SCULPT lighting will provide precise occupancy and activity information to other building services like HVAC, security, smart power distribution, space utilization, and so on, making broader building sentience more attainable.

DiLouie: What applications do you see as early adopters for this type of solution?

Karlicek: We see the early adopters being in commercial and healthcare facilities, where activity driven illumination profiles can save energy, adjust spectral power distributions with defined vertical illuminance profiles, and make the occupant data needed to achieve that level of lighting control available to a wider set of “sentient building” operations.

DiLouie: Do you see adoption ultimately being driven primarily by lighting applications (which can become part of smart buildings) or by overall smart buildings (which will pull lighting into it)?

Karlicek: This is a great question, and in reality, we believe that the smart building operations would benefit the most and provide the best return on investment, and steerable, tunable lighting would be an important fringe benefit. It will really be the high fidelity, privacy preserving occupant activity estimation capabilities for the sentient building that will drive adoption.

DiLouie: Imagining a future product, what would be different for electrical contractors? Would this be more or less difficult to specify, install, and commission? Would there be any new opportunities?

Karlicek: We expect that specifications would be set out by architects and lighting designers, and there would be no room for substitution of either the specified fixtures and their location, or the distributed sensor networks that enable autonomous operation. The commissioning operation would likely be different, with simulations and testing having been performed ahead of installation using virtual reality (VR) software, with field changes also being evaluated using VR. Commissioning post installation would be performed as it is now, but would be aided with augmented reality (AR) systems.

DiLouie: What would a typical user experience look like under this type of solution?

Karlicek: Initially, the users might need to get used to lighting that changes as they move and change their activities. We are curious about what user acceptance of spatially and spectrally adaptive lighting will look like. While we are not currently looking to build machine learning and artificial intelligence into the control system, future versions of SCULPT would likely incorporate those capabilities, so the illumination adaptability would get more comfortable for the user over time.

DiLouie: If you could tell the entire electrical industry only one thing about spatially tunable lighting, what would it be?

Karlicek: LEDs are continuing to unleash a broad range of new lighting technologies that will require continuous training of the experts that specify, install and maintain lighting systems. We are just at the tip of the iceberg.

DiLouie: Is there anything else that you’d like to add about this topic?

Karlicek: If we can have autonomous, self-driving cars and trucks, we can certainly achieve autonomous, high quality spatially and spectrally adjustable lighting that knows what lighting is needed where and when. That is what we aim to show.

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IR LEDs Can Detect Gaseous Signatures, Opening New Applications

The University of Melbourne, Lawrence Berkeley National Laboratory, University of California Berkeley, and Australian Research Council Centre of Excellence for Transformative Meta-Optical Systems (TMOS) have collaborated on the development of a device that could identify various gases, potentially including lethal ones.

The University of Melbourne, Lawrence Berkeley National Laboratory, University of California Berkeley, and Australian Research Council Centre of Excellence for Transformative Meta-Optical Systems (TMOS) have collaborated on the development of a device that could identify various gases, potentially including lethal ones. The work appeared in the journal, Nature.

Infrared (IR) spectrometers are common laboratory equipment that can identify different materials by analyzing their infrared signatures, which is invisible to the human eye. Just like an AM radio can be tuned to different frequencies of radio wave, IR spectrometers can be tuned to different wavelengths, giving a broad-spectrum analysis of a gas sample. However, these machines are bulky and expensive and not usually practical to take out of the laboratory and into the field.

“Our new technology bonds a thin layer of black phosphorus crystals to a flexible, plastic-like substrate, allowing it to be bent in ways that cause the black phosphorus to emit light of different wavelengths essentially creating a tunable infrared LED that allows for the detection of multiple materials,” University of Melbourne Professor Kenneth Crozier said. “This technology could fit inside smartphones and become part of everyday use.”

For example, the bacteria found in meat release various gases as they multiply. The presence of these gases is a good indication that the meat is spoiling and is no longer fit for consumption.

“The device placed inside a fridge could send a notification that meat is going off. When pointed at a handbag, it could reveal whether the bag is made of real leather or a cheaper substitute,” said Professor Crozier, who is also the Deputy Director of TMOS.

Current materials that are used for IR photodetectors and light emitting devices can be difficult to manufacture, in large part due to the need for multiple layers of perfectly linked crystals. This new black phosphorus technology requires just one layer allowing  the device to be flexible, giving it unique properties when bent.

“The shift in black phosphorus’ emission wavelength with bending is really quite dramatic, enabling the LED to be tuned across the mid-infrared,” said Professor Ali Javey, from the University of California at Berkeley, whose group led the work.

Importantly, the device could make the work of firefighters, miners and military safer, allowing them to identify potentially lethal gases from safe distances as the ultra-thin, ultra-light devices can be placed on small drones. Flying such a drone over a building fire could tell firefighters what dangers they face and equipment they’ll need.

The low-cost technology could also make its way into devices for use by plumbers and building managers.

“Our IR photo detectors could be integrated into a camera so that we could look at our phone screen and ‘see’ gas leaks or emissions and be able to determine what kind of gas it is,” Professor Crozier said.

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DesignLights Consortium Seeks Assistance for Study of Non-Energy Benefits of Networked Lighting Controls

As it seeks to quantify the non-energy benefits of networked lighting and advanced building controls, the DesignLights Consortium (DLC) is asking for input from facility managers for a short online survey. Results of this research will yield monetized estimates useful for product marketing, efficiency program incentive promotion, and facility management decision making.

As it seeks to quantify the non-energy benefits of networked lighting and advanced building controls, the DesignLights Consortium (DLC) is asking for input from facility managers for a short online survey. Results of this research will yield monetized estimates useful for product marketing, efficiency program incentive promotion, and facility management decision making.

“Networked lighting controls (NLC) and other advanced building controls have reported benefits beyond energy savings, including improved occupant productivity and comfort, reduced maintenance, improved space utilization and lower carbon emissions,” DLC Technical Director Stuart Berjansky said. “Aside from limited case study evidence, however, minimal data exists to support and quantify these advantages. The DLC’s study aims to close that gap.”

The study is focusing on four building types: office buildings, hospitals and health care facilities, educational buildings, and warehouse and light industrial facilities, and covers a range of advanced controls including NLCs; integration of building systems that allow information sharing between NLCs and other systems; building IoT that provides data about the conditions within a building; and analytics applications that collect information from building systems.

With a goal of completing surveys by the end of September, the DLC is seeking facility managers to complete a 15- to 20-minute web-based anonymous survey, and to send their building occupants a link to complete a separate five-minute survey. Both surveys ask respondents about their experiences with various control measures and include comparison questions to establish relative values among different non-energy benefits. The DLC plans to complete the survey phase of the study by the end of September.

To protect confidentiality, the DLC is not requesting confidential data, the release of sensitive customer contact information or sharing of customer identities. In all cases, the DLC will not divulge any information or results about individual buildings or persons contacted.

Facility managers interested in the survey should send an email requesting a survey link to the DLC’s contractor, Lisa Skumatz of Skumatz Economic Research, at skumatz@serainc.com. To broaden the reach of this research, the DLC is also requesting design professionals, integrators, sales agents, manufacturers and contractors who have been involved relevant projects to inform their facility managers about the study. The DLC will provide a copy of survey results to any company that connects the study team with site managers who complete the survey.

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Spatially Adaptive Tunable Lighting Addresses Indoor Illumination Challenges

Imagine walking into a conference room where there are no light switches or lighting control panels. Rather the light is “aware.” It automatically responds to where you are in the room, where others are and the tasks they are performing while smoothly adjusting illuminance to the precise lighting needed to optimize comfort, productivity and circadian function.

Guest post by Leah Scott

Imagine walking into a conference room where there are no light switches or lighting control panels. Rather the light is “aware.” It automatically responds to where you are in the room, where others are and the tasks they are performing while smoothly adjusting illuminance to the precise lighting needed to optimize comfort, productivity and circadian function. In fact, you won’t have to do anything to the lights because the lighting designer is embedded in the smart lighting system. An automatic, beam-steerable lighting control system provides an intelligent, autonomous solution for estimating room occupants’ ideal illumination profiles and “sculpts” the light accordingly without wasting light where it isn’t needed.

To illuminate different lighting scenes, lighting designers typically need to install multiple troffers, recessed cans, focused spotlights, wall-washing lighting, or sconces to create a variety of appropriate lighting scenarios for occupants. Lighting controls that currently deliver light from multiple luminaires in real-time for specific activities are not adaptive, tunable, or are unable to deliver smooth lighting transitions without some type of human intervention with the lighting control system. The occupants’ ability to manage an ordinary lighting system for specific activities is limited. Even some of the most basic lighting control systems are relatively primitive and difficult to use. As lighting systems move to spectral tuning, fully autonomous controls are required, since there would be far too many settings, diverse scenes and activities, various fixture types, and spectral control factors involved for the average building occupant to operate.

Funded by the Building Technologies Office (BTO) of the Department of Energy (contract No. EE0009167), the Sculpt Program brings together industry and academia. Rensselaer researchers at the Lighting Enabled Systems and Applications Center (LESA) and the Center for Architecture Science and Ecology (CASE) are joined by LESA industry member Lumileds and global architectural design firm HKS, Inc. to develop a spatially adaptive tunable lighting control systems with expanded wellness and energy saving benefits. The aim of Sculpt is to address three main indoor lighting challenges: static or fixed-profile light fixtures cannot dynamically place lighting only where it is needed; tracking occupants with PIR motion sensors does not provide accurate activity specifications for added energy saving; and the emerging use of color tunable fixtures makes human control over the systems even harder.

The Rensselaer research team is utilizing tools such as Microsoft Kinect and Unity, an open-source gaming engine, to develop the autonomous control system in a VR simulation environment. The Microsoft Kinect is utilized to locate occupants, determine poses and gaze direction, and estimate activity type. By importing this information into Unity, both the occupants and lighting profiles can be visualized in real-time. Using this digital-twin simulation approach, developers are able to visualize many lighting scenarios and activities for deeper understanding of the human factors involved in dynamically adjusted illuminance profiles for autonomous occupancy-driven lighting control. The VR simulations help train the embedded lighting designer on how to dynamically redistribute light and adjust spectral power distributions as required to create smooth light transitions as occupants move and the scenes change. The VR tool also aids in the development of control algorithms that minimize glare and shadows while sculpting the illuminance to save energy.

Lumileds is providing the beam steerable, color-tunable light engines, and Rensselaer is developing the occupancy sensing and lighting control algorithms. HKS is applying its expertise in lighting simulations, energy use calculations, and circadian simulation tools that factor in the lighting’s spectral power distribution, occupant gaze, and the spectral reflectivity of room surfaces. The completed system will be deployed in LESA’s Smart Conference Room for calibration and performance evaluation during 2022.

“Just as the vision of a self-driving car will include an embedded expert driver, we are developing the concept of an embedded lighting designer for autonomous lighting systems,” says LESA Center Director Robert Karlicek. “The integration of advanced lighting systems, novel sensing platforms, and embedded intelligent control, has always been part of the LESA vision. Once the lighting system is smart enough to optimize illumination, its knowledgebase can be used to control other building systems removing control burdens from building occupants and managers that continuously learn how to further improve building energy efficiency, human comfort, productivity and wellbeing.”

Once deployed, the Sculpt System will serve as a testbed for the continued development of autonomous lighting and integrated building control systems. Researchers will also be able to document the evaluation of how digitally controllable vertical and horizontal illuminance using different spectral power distributions can improve circadian health. The testbed will also be used for the development and testing of novel (and lower cost) approaches to occupant location and pose sensing. The knowledge gained in the testbed will advance the improvement of occupant-centric control systems by providing comprehensive data for both lighting control as well as important building services such as HVAC energy reductions and other building management services. The sensing and control platform will provide a first glimpse of future sentient occupant-centric building management systems.

 

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Researchers Acquire 3D Images with LED Room Lighting and a Smartphone

Researchers at the University of Strathclyde in the UK have developed a process to use dynamically controlled LEDs for 3D imaging.

In The Optical Society (OSA) journal Optics Express, Researchers at the University of Strathclyde in the UK demonstrated that 3D optical imaging can be performed with a cell phone and LEDs without requiring any complex manual processes to synchronize the camera with the lighting.

“Current video surveillance systems such as the ones used for public transport rely on cameras that provide only 2D information,” said Emma Le Francois, a doctoral student in the research group led by Martin Dawson, Johannes Herrnsdorf and Michael Strain at the University of Strathclyde in the UK. “Our new approach could be used to illuminate different indoor areas to allow better surveillance with 3D images, create a smart work area in a factory, or to give robots a more complete sense of their environment.”

Human vision relies on the brain to reconstruct depth information when we view a scene from two slightly different directions with our two eyes. Depth information can also be acquired using a method called photometric stereo imaging in which one detector, or camera, is combined with illumination that comes from multiple directions. This lighting setup allows images to be recorded with different shadowing, which can then be used to reconstruct a 3D image.

Researchers developed a way to use overhead LED lighting and a smartphone to create 3D images of a small figurine.

Photometric stereo imaging traditionally requires four light sources, such as LEDs, which are deployed symmetrically around the viewing axis of a camera. In the new work, the researchers show that 3D images can also be reconstructed when objects are illuminated from the top down but imaged from the side. This setup allows overhead room lighting to be used for illumination.

“Deploying a smart-illumination system in an indoor area allows any camera in the room to use the light and retrieve the 3D information from the surrounding environment,” said Le Francois. “LEDs are being explored for a variety of different applications, such as optical communication, visible light positioning and imaging. One day the LED smart-lighting system used for lighting an indoor area might be used for all of these applications at the same time.”

In work supported under the UK’s EPSRC Quantic research program, the researchers developed algorithms that modulate each LED in a unique way. This acts like a fingerprint that allows the camera to determine which LED generated which image to facilitate the 3D reconstruction. The new modulation approach also carries its own clock signal so that the image acquisition can be self-synchronized with the LEDs by simply using the camera to passively detect the LED clock signal.

“We wanted to make photometric stereo imaging more easily deployable by removing the link between the light sources and the camera,” said Le Francois. “To our knowledge, we are the first to demonstrate a top-down illumination system with a side image acquisition where the modulation of the light is self-synchronized with the camera.”

In a public area, LEDs could be used for general lighting, visible light communication, and 3D video surveillance. The illustration shows multiple access LiFi — wireless communication technology that uses light to transmit data and position between devices — and visible light positioning in a train station.

To demonstrate this new approach, the researchers used their modulation scheme with a photometric stereo setup based on commercially available LEDs. A simple Arduino board provided the electronic control for the LEDs. Images were captured using the high-speed video mode of a smartphone. They imaged a 48-millimeter-tall figurine that they 3D printed with a matte material to avoid any shiny surfaces that might complicate imaging.

After identifying the best position for the LEDs and the smartphone, the researchers achieved a reconstruction error of just 2.6 millimeters for the figurine when imaged from 42 centimeters away. This error rate shows that the quality of the reconstruction was comparable to that of other photometric stereo imaging approaches. They were also able to reconstruct images of a moving object and showed that the method is not affected by ambient light.

In the current system, the image reconstruction takes a few minutes on a laptop. To make the system practical, the researchers are working to decrease the computational time to just a few seconds by incorporating a deep-learning neural network that would learn to reconstruct the shape of the object from the raw image data.

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ELECTRICAL CONTRACTOR: Exit Sign Brightness Study

As lumen depreciation is a significant failure mode with LED lighting, it raises the question whether some older exit signs are still producing sufficient brightness to be visible in smoky conditions. This is the subject of a new study being undertaken by NALMCO in partnership with the Icahn School of Medicine at Mount Sinai in New York, and the topic of an article I wrote about the study for the January issue of ELECTRICAL CONTRACTOR.

As lumen depreciation is a significant failure mode with LED lighting, it raises the question whether some older exit signs are still producing sufficient brightness to be visible in smoky conditions. This is the subject of a new study being undertaken by NALMCO in partnership with the Icahn School of Medicine at Mount Sinai in New York, and the topic of an article I wrote about the study for the January issue of ELECTRICAL CONTRACTOR.

Click here to check it out.

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ELECTRICAL CONTRACTOR Publishes 2020 CII Lighting Trends Survey

The electrical contracting community experienced significant economic impacts from the COVID-19 pandemic but is somewhat optimistic about 2021. That is one key finding from the 2020 Commercial/Industrial/Institutional (CII) Lighting Trends Survey, conducted by ELECTRICAL CONTRACTOR in October among the magazine’s Subscriber Research Panel. The survey and article were my contribution to the magazine’s December 2020 issue.

The electrical contracting community experienced significant economic impacts from the COVID-19 pandemic but is somewhat optimistic about 2021. That is one key finding from the 2020 Commercial/Industrial/Institutional (CII) Lighting Trends Survey, conducted by ELECTRICAL CONTRACTOR in October among the magazine’s Subscriber Research Panel. The survey and article were my contribution to the magazine’s December 2020 issue.

Among the key findings:

* A majority of respondents said the COVID-19 pandemic impacted their 2020 business revenues, with the majority of these respondents saying their overall revenues decreased, not just for lighting.

* Overall, respondents are optimistic about 2021, with more saying they expect their revenues related to lighting in all three markets will increase in 2021 than those saying it will decrease. About 30%–40%, however, believe their revenues will remain unchanged.

* A majority of respondents are familiar with major lighting trends, with the greatest familiarity or actual work experience being with wireless lighting controls (73%), color-tunable lighting (63%) and networked lighting controls (61%). Three-fourths of respondents are least familiar with germicidal lighting and the IoT, which is not surprising, because these are relatively new trends. However, upward of three-quarters of respondents who are aware of the technologies are comfortable specifying and installing each of them, with the least comfort for germicidal lighting, IoT and networked lighting controls.

* More than 60% of respondents have discussed lighting quality and color-tunable LED lighting as lighting product features/trends with customers. Nearly half have discussed networked lighting controls. Customers were most interested in lighting quality, followed by color tuning and networked control. However, more than three-quarters were somewhat or very interested in all five technologies.

* The average respondent considers ECs as having a somewhat high degree of influence in selecting lighting equipment for new construction and major renovation CII projects and the highest degree of influence in lighting retrofits.

Check out the article here.

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