Image courtesy of Muhammad Hegazy

Let there be light: How Unreal Engine is helping us design healthier spaces

Pierre-Felix Breton
Studies have shown that even before the pandemic, we spent 90% of our time indoors. Unsurprisingly, this is having detrimental effects on our health. Decreased sun exposure is linked to lower vitamin D and serotonin levels, which can lead to depression, low productivity, poor sleep, and even increased cancer risk.

Luckily, Muhammad Hegazy, architect and researcher at Osaka University’s Graduate School of Engineering program has a solution. Since 2018—working jointly with Associate Professor Kensuke Yasufuku and Professor Hirokazu Abe— he’s explored how Unreal Engine can help architects make more informed decisions when it comes to maximizing natural light.
Image courtesy of Muhammad Hegazy
Today, his research has resulted in a human-centered lighting system that’s received multiple international awards and been featured in publications and conferences including the IEEE Conference on Virtual Reality, VELUX Daylight Symposium, BuildSim Nordic Conference, and the Journal of Asian Architecture and Building Engineering.

The creative spark

“Improving lighting once a building is already constructed is often complicated and costly,” Hegazy explains. “Instead, it’s best to accurately previsualize how a space will look, so that architects can select the designs that would improve most people’s well-being before construction begins.”

To help figure out what will benefit people the most, lighting designers and researchers typically render panoramic HDR images of a space, then ask future occupants to detail their perception of different lighting types in a questionnaire. The problem is there’s often a big difference between a 2D image and a real-world building—particularly one that can look and feel different depending on factors like weather or the time of day.

“I wanted our project to go beyond the limitations of these HDR studies,” Hegazy continues. “I knew Unreal Engine was becoming a tool of choice for real-time architectural visualization, and found its implementation of physically-based lighting, including sunlight and skylight, to be far superior to any other solution in terms of realism. Instead of static HDR images, I decided to use Unreal Engine to create a virtual environment that occupants could walk through, interact with and customize in real time. I wanted them to be able to report their feedback on lighting while still experiencing the virtual space.”

Testing the theory

Soon, Hegazy had created an immersive visualization system for perceiving daylight in VR, which he theorized would help lighting designers and architects create healthier indoor spaces, faster. To test the system out, he decided to create a virtual model of Louis Kahn's Kimbell Art Museum, which is famous for its sophisticated—and complicated—lighting design.
Image courtesy of Muhammad Hegazy
“Creating a virtual model of the museum was tricky,” Hegazy remembers. Luckily, as the museum is highly recognized for its architectural heritage, Hegazy could rely on a wide range of available technical drawings and documentation to help. Using these references, he created a 2D plan of the building in AutoCAD, before exporting it to 3ds Max for the creation of 3D geometry and preliminary materials.

The next step involved transferring the model from 3ds Max to Unreal Engine. “This was very easy using the Datasmith plugin, which could correctly export all the meshes to Unreal Engine without much need for optimization,” Hegazy explains. “We then used SunSky to accurately set up the sun’s position, luminance, and tone in Unreal Engine. After this, we used Blueprints to create a wide range of interactions for anyone experiencing our virtual museum, such as walking, jumping, or changing the time of the day. This meant we could offer a much richer experience of the space in different lighting conditions—all without having to write C++ code.”
Image courtesy of Muhammad Hegazy

Along with running, jumping, and time shifts, users experiencing Hegazy’s virtual museum in VR could also take snapshots of the space, then give real-time feedback about their perception of the lighting in each shot. As a necessary validation step, the project’s second phase featured a comparative study of daylight perception in the real museum, which Hegazy then compared against its virtual replica, using identical spatiotemporal settings.

Creating healthier environments

By the end of the museum project, Hegazy discovered that the human perception of daylight in virtual space was not significantly different from real space, despite VR hardware’s limitations in terms of field of view and luminance. Participants in both environments pinpointed similar areas of interest and rated them similarly in terms of brightness.

“This finding is of significant importance because it confirms that virtual environments are an accurate way of improving lighting in architectural spaces,” Hegazy explains. “This not only has the potential to hugely benefit our mental and physical health in the real world. It also means we now have the level of realism and interaction needed to build the next generation of human experiences through virtual environments in the metaverse.”
Image courtesy of Muhammad Hegazy

And in Hegazy’s eyes, this is going to get pushed even further with the introduction of Lumen, Unreal Engine 5’s dynamic global illumination and reflections system.
“Lumen isn’t just a game changer for the gaming industry, its revolutionary approach can have great applications for archviz and lighting design, as well,” says Hegazy. “In our line of work, the accuracy of light representation and a person’s immersion level are mandatory for accurate feedback. With Lumen, we get real-time dynamic lighting—without the performance compromises that used to hold us back.”

Immediate use cases include simulating a whole day’s world of light and sky conditions, without resorting to a fixed daylight scenario. While these changes might initially be driven by the team, Hegazy sees a future where interactive tools are built into the simulation, so participants can  change conditions in the moment and register feedback under a wider range of variables.
Design and model courtesy of Safdie Architects

“The more dynamic we can make a scenario, the more data we can get about how people interact with it. Lumen is going to help us get there a whole lot faster.”

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