If you’re a Whitney Houston fan, I have either good news or bad news for you: She’s going on tour! This week, entertainment company Base Hologram and Houston’s estate announced “An Evening With Whitney: The Whitney Houston Hologram Tour.”
Houston joins the ranks of several other megastars performing posthumously. Base also offers a Maria Callas tour and one with Roy Orbison and Buddy Holly, and it’s been working on an Amy Winehouse performance. Base’s competitors at Eyellusion are putting on a Frank Zappa tour this year. Both companies have been founded in the past few years—Eyellusion in 2015, Base in 2017—to usher in a new era of performance that “combines holographic realism with live entertainment,” creating “a real-life 3D production,” according to Base’s site. And several news outlets discussing the announcement have adopted similar language, calling the Houston rendering a “3D hologram.” While some fans have taken to social media to protest their celebrity’s likeness being used in such a way, I have a more pedantic bone to pick: The Whitney you’ll see on tour will be neither 3D nor a hologram.
Take what’s perhaps the best-known “3D hologram” performance: Tupac at Coachella 2012. That was actually a projection onto angled sheets of plastic, using an illusion called Pepper’s ghost, named after the scientist who popularized the method. “It’s like when you’re window-shopping and you see yourself in the store glass; it’s the same effect,” says Daniel Smalley, an associate professor of electrical engineering at Brigham Young University. That trick of light and reflection has been in use since the 1500s, says Smalley, and became especially popular among Victorian-era magicians and theater productions—so, not exactly cutting-edge technology. Essentially, what you’re seeing is a projected 2D image; the 3D illusion would quickly fall apart if you saw it up close or changed your viewing angle. Eyellusion’s Zappa tour uses this same basic method as well.
That Tupac performance planted the seed for Base Holograms, according to co-founder Marty Tudor. “I thought, this is really cool—why do just a one-off? Why not a whole evening?” But unlike Tupac’s performance, Houston’s image won’t rely on Pepper’s ghost. “We’re way past Pepper’s ghost,” says Tudor, though he didn’t provide other details about their proprietary technology. He did say, however, that the image is not a reflection and is a direct projection using a cutting edge, “military-grade” Epson laser projector. Whatever this projection is, Tudor confirms, it’s not 3D, though it may appear that way to the audience. “It’s what the projector does that makes it appear 3D,” he says.
When I asked Benjamin Klein, an associate professor at the Georgia Institute of Technology School of Electrical and Computer Engineering, whether he had any guesses about what methods Tudor’s team could be using instead of Pepper’s ghost, he was honest: “I think he’s almost certainly bullshitting you, but I could be wrong,” Klein says. “Of course, a magician never reveals his secrets, and this is, at the bottom, a magic trick.”
Smalley was similarly skeptical. “If they’re using any kind of projector, laser or otherwise, then the technology will undoubtedly be a 2D projection like Pepper’s ghost,” he says. Perhaps the proprietary bit is a special scrim, or projecting onto heated air or water vapor, Smalley says, “but all of these cases are just variations on the same theme.”
Whether you’re using Pepper’s ghost or something else, developing the celebrity image that gets projected is a computational feat. “The creation of the video projected probably involved a lot of digital manipulation,” says Klein. Tudor says that it takes between nine months to a year to develop a Base show, from script to tour, and that the team uses CGI to create a hologram “the same way you create people for the movies.” Creating Coachella Tupac, according to Wired, required artists to work “round the clock for two months in a room plastered with pictures of the rapper,” and he was only onstage a few minutes. The renderings and choreography for a full show would be an even heavier lift.
These touring celebrity renderings are also not true holograms. That’s because there’s a disconnect between what scientists call holograms and how the word hologram is used in pop culture. “What people think of when they hear hologram is Princess Leia from Star Wars—you project it and you see it from every direction,” says Smalley. But real holograms can’t be seen from a 360-degree view the way Leia can. They are, by definition, images on flat surfaces that look 3D by interfering with light beams that reflect off of that stable surface—one common example is the security sticker found on many credit cards. It’s much more difficult to create a real, moving hologram that looks 3D, though scientists are working on making those.
If you’re hoping for a bona fide Princess Leia situation, what you want is a free-space volumetric display. Smalley and his team made a teeny-tiny version of Princess Leia last year by using a laser beam to trap and rapidly heat one tiny particle of paper, allowing the scientists to manipulate its movements. Then, scientists illuminated that particle with rapid red, green, and blue light to create the illusion that you’re drawing an image—“like a sparkler on the Fourth of July,” says Smalley. There’s only so much you can draw with just on particle, so the images they’ve created are only a couple centimeters tall, and Smalley estimates researchers would need at least another 6,000 hours to scale up their methods to an 8-inch prototype, and probably at least another 6,000 hours for something human-size, “if that’s even possible,” he says.
Beyond posthumous tours, those volumetric displays could have other applications. Smalley says that air traffic controllers could keep tabs on 3D models of planes’ paths to prevent accidents, surgeons could perform image-guided surgeries with 3D renderings, or video conferencing could become much more realistic. And, of course, the adult industry is working on using volumetric images for more lifelike porn.
In the meantime, these projections will do just fine for a celebrity tour. “A hologram is overkill for what you need here, and if it looks good to you, then don’t worry too much about whether it’s 3D or not, ” says Klein. After all, you can have a 3D experience without the rendering of Whitney Houston you’re watching necessarily being 3D. Base shows include live musicians, singers, and dancers—the whole shebang. And Tudor emphasizes how real the projection appears, saying even he is fooled by it after seeing it hundreds of times. “Your brain cannot tell the difference,” he says.
Smalley agrees that whether the image is actually 3D or “Leia-like” seems moot for these performances. “There’s no reason to spend extra time, money, and engineering that no one will benefit from,” he says. “Though if you wanted to shake Whitney Houston’s hand, you gotta have it.” But even then, it would just be a trick of light; she might look convincing up close, but your hand would just go through hers.