Capturing Ancient Graffiti with Photogrammetry, Laser Scanning, and 3D Imaging

History From Scratch
Cutting-edge tools are rescuing ancient graffiti from obscurity—and preserving them forever

by Amy Crawford for Smithsonian Magazine

BEGINNING WITH ITS construction in the fourth century B.C. and continuing for more than 800 years, the Temple of Isis on the small island of Philae, set where the Nile flowed out of Nubia, was visited by a stream of pilgrims. Coming from all parts of the Egyptian empire, and even as far away as Cyprus and Rome, they passed between 60-foot towers to attend elaborate seasonal ceremonies that celebrated Isis’ miraculous resurrection of her husband, the god Osiris, and the birth of their son, Horus. They beseeched Isis, the queen of the Egyptian pantheon, for aid and thanked her for interceding in their affairs.

Before heading home, many also etched their marks—a carving of their footprints on sacred ground, a picture of the deity, a name, a date or perhaps a short prayer—into the temple’s massive sandstone blocks. Some testified to the difficulty of their journey: “Isis, you are the Mistress of the Road,” wrote a third-century A.D. Nubian envoy named Sasan, beside a crude self-portrait. “Our hearts are entrusted to you upon the way.” Others were likely carved on pilgrims’ behalf by the priests who worked at the temple: “His name endures forever: Nesmety, the banker of Isis....As for the one who will erase these writings, his name will be erased forever.”

When European explorers began visiting Philae in the 19th century, more than a millennium after the cult of Isis slipped into history, they labeled these informal inscriptions “graffiti,” from the Italian for “scratches.” To these visitors, the phenomenon was a curiosity, at best—and at worst, vandalism. (Contemporary graffiti, like the messages recently carved by tourists on the wall of Rome’s Colosseum, is still considered vandalism.) For generations, most archaeologists were principally interested in the temple’s epic architecture and the official ornamentation on its walls, which include intricate reliefs of gods and goddesses carved by skilled artisans.
But over the last two decades, the etchings of the worshipers at Philae and other sites across the ancient world have gradually become the focus of serious inquiry, part of a broader turn away from the monarchs and monuments that long dominated our study of the past—and limited our historical perception.
“People are looking more at women, the enslaved, people who have been left out of the historical record—and graffiti are really one of the best ways to get at these voices,” says Jacqueline DiBiasie-Sammons, a classicist at the University of Mississippi, whose research centers on graffiti in the doomed Roman cities of Herculaneum and Pompeii.
The tools of ancient graffiti artists were simple—a knife, a chisel, perhaps a stick of charcoal. But these researchers have the advantage of breakthrough technology that is helping them recover, preserve and publicize these etchings, from sophisticated image capture to massive online databases and even artificial intelligence.

The Ancient Graffiti Project has digitized thousands of Roman graffiti since its founding at Washington and Lee University in Virginia in 2014. In Italy, researchers are documenting graffiti in medieval churches using a technique called photogrammetry. Last year, an international team of researchers debuted “Ithaca,” a deep neural network—a form of artificial intelligence—designed to read damaged or incomplete Greek inscriptions. And, in one of the most ambitious projects to date, a Canadian team has been working since 2016 to create a 3D model of the Temple of Isis that will allow researchers to explore, in intimate detail, the devotions of people like Sasan and Nesmety, who lived and died millennia ago.

THE PHILAE TEMPLE complex is, technically, no longer on Philae. In the late 1970s, it was carefully disassembled and moved, block by block, to Agilkia, a higher island a quarter-mile downriver, after Philae was flooded by the construction of the Aswan High Dam. Still, Isis’ rebuilt temple retains its power to inspire awe, looming over the Nile as visitors approach in flat-bottomed river boats, much as pilgrims might have done in the age of the pharaohs.
“That ferry ride never ceases to amaze me,” says Sabrina Higgins, an archaeologist at Simon Fraser University in British Columbia and a co-leader of the Canadian research team. “To go to Philae feels as if you are stepping back in time.”

It’s easy to imagine the festivals and rituals that once took place here, Higgins says—the flotillas bearing effigies of the gods, the solemn re-enactments of Osiris’ funeral rites. That’s especially true early in the morning, before all the tourists arrive, when the island is the sole domain of hundreds of feral cats, who are fed by workers there, in a throwback to the age when Egyptians considered felines to be divine. It’s also the time of day when, thanks to the angle of the sun, the graffiti is easiest to capture in photographs.

Much of Philae’s graffiti consists of prayers and names in Demotic script, a form of Egyptian writing that succeeded hieroglyphics, used primarily by priests and officials in an era when few people could read and write. Higgins and her colleagues, though, are concentrating on figural graffiti, which range from humans and animals (often representing a god) to game boards likely carved by Isis’ priests for diversion during their off hours. A falcon in flight honors Isis’ son Horus, the great god commonly depicted with the head of a bird of prey. A crude line drawing of a horse is set so high on a wall that the artist must have been sitting on the roof with his legs dangling over the edge.

“The figures are at least as interesting” as textual graffiti, says Jitse Dijkstra, a classicist at the University of Ottawa, who has been studying Philae’s graffiti for more than 20 years and was among the first scholars to examine it seriously. Dijkstra began the current survey in 2016 with his Ottawa colleague Roxanne Bélanger Sarrazin. Higgins joined the project in 2020 and later recruited Nicholas Hedley, a geographer at Simon Fraser who has previously worked with oceanographers to map the seafloor and with NASA to model the surface of Mars. Hedley contributed his expertise in digital visualization, plus a dazzling array of high-tech gadgetry, which the team believes will one day be central to future graffiti projects.

Hedley began his survey with photogrammetry, a technique originally developed for architectural surveying in the 19th century that has become increasingly powerful since the advent of digital photography. Digital photogrammetry uses a mosaic of hundreds of overlapping images, each captured from a slightly different angle, to construct a high-definition, three-dimensional representation of each surface—not only walls but also rooftops, stairwells and the sides of columns. But photogrammetry requires unbroken light, which can be rare in the Philae complex, so on a subsequent trip, Hedley brought a brand-new piece of technology: a small, powerful laser scanner, about the size of a soda can. Even in the temple’s darkest recesses, the device could capture images of graffiti that may have been unseen by human eyes for centuries.

“That was a game changer,” Bélanger Sarrazin says of the new, portable laser scanner. “In 2016, we were still using tracing paper on the walls. Later, we changed to doing drawings from photographs, but sometimes on the photographs we don’t see all the details, the depths, the texture of the wall and the graffiti in its context.”

Context can reveal a lot about where pilgrims were allowed to go, which areas were limited to priests and how worshipers chose to express their devotion. On a Zoom call from his office at Simon Fraser, Hedley walks me through a 3D model-in-progress and notes a particular concentration of graffiti just outside the most hallowed part of the temple, where people apparently chipped off pieces of sandstone as souvenirs. The human-made gouges and the graffiti in this spot, Hedley says, suggest that many worshipers were prevented from entering and instead crowded outside. “There would’ve been thresholds of access,” Hedley says. “This was the holiest of holies.”

Much like Philae’s ancient pilgrims, today’s tourists do not have full access to the Temple of Isis—nor can everyone travel to this fairly remote part of southern Egypt. But the Canadian team is working to create a detailed digital model of the entire temple that they plan eventually to make widely accessible.

“Nobody has thought to use this kind of technology for capturing graffiti before,” Higgins says.

“As a conservator and someone who has studied ancient graffiti, I think this is a wonderful form of preservation,” says Suzanne Davis, head of conservation at the University of Michigan’s Kelsey Museum of Archaeology and the president of the American Institute for Conservation, who has been following the project from afar. “But it also has the huge benefit of making the graffiti available to students and scholars all over the world."

“Ancient graffiti do show us how much things have changed in 2,000 years, but they also show us how much is just part of the human condition,” Di-Biasie-Sammons says.

After all, at any given time in history, everyday people are living their ordinary lives. Few of us will build monuments, live in palaces or have our names and deeds recorded in official histories. Still, the urge to leave a mark seems universal, whether it’s a declaration to a deity, to posterity, or simply to oneself: “I was here.” ◆