PARIS — "A cloud of unusual size and appearance," Pliny the Younger said of the smoke he saw rising above Mount Vesuvius on Aug. 24, in the year 79. "I can best describe its shape by likening it to a pine tree. It rose into the sky on a very long trunk from which spread some branches," he wrote in a letter to Tacitus.

From his vantage point in the town of Miseno, some 20 kilometers away, Pliny had an unobstructed view of the unfolding disaster, which buried the towns of Herculaneum, Oplontis and Stabiae — stuck as they were between the volcano and the bay of Naples — under several meters of pumic stone and ash. Pompeii suffered the same tragic fate.

Herculaneum and especially Pompeii, a small thriving town at the time of the eruption, would become famous centuries later because of how they were inadvertently preserved by the disaster. Since their discovery in the 18th century, the ruined towns have been an ongoing subject of fascination, as much so for today's scientists as it was for their predecessors.

In the 19th century, excavation supervisor Giuseppe Fiorelli developed a casting method (liquid plaster poured into the empty spaces left by the bodies stuck in the layers of volcanic scoria and little by little reduced to dust) that provided tangible images of the residents of Pompeii exactly as they were when death came upon them. Those casts — of people running out of a home, protecting a child in one's arms, sheltering one's fortune — are as striking now as they were when Fiorelli made them.

Researchers today have come up with an entirely new way of reconstituting the nearly 1,000-year-old disaster. The approach, which uses bytes rather than plaster, and processing power instead of physical excavation, was developed by French researchers and engineers from Microsoft Research and the French Institute for Research in Computer Science and Automation (INRIA), along with help of the startups Iconem and Cintoo 3D.

Down to the last centimeter

Participants in the "Digital Pompeii" project, which was presented earlier this year at Microsoft's Build conference in San Francisco, used digital animation to provide a virtual and interactive journey in, or rather above, Pompeii's ruins, which they digitally recreated centimeter by centimeter.

The adventure began two years ago with the development — in a computer lab shared by France's École Normale Supérieure (ENS), INRIA, and National Center for Scientific Research (CNRS) — of a new method allowing the automatic construction of a 3D model from aerial pictures taken by a drone. This process was first tested on one of Pompeii's most famous monuments, the Villa of Diomedes, a masterpiece of Pompeii's architecture. The experiment was so successful that architect Yves Ubelmann, founder of Iconem, was convinced that the entire site could be mapped in this way.

The 3D model they eventually produced required some 30,000 images taken by a balloon-assisted drone that was equipped with sensors and a robotic arm and spent some 50 hours flying over the site.

The INRIA developed the algorithms needed to match the images and recalculate the perspective. Microsoft, via the Microsoft Azure cloud, provided the processing power required to make the algorithms work. Overall, the operation required 1,200 hours of calculations. And the startup Cintoo 3D provided technology allowing anyone with a simple Internet browser to travel as they please in the virtual town.

A global view of the Digital Pompeii project Photo: Microsoft

Beyond this general use application, the Digital Pompeii project is also very appealing to researchers, be they archeologists, technique historians or Ancient Rome specialists.

The secret texts of Herculanum

People with an interest in Pompeii are likely to be interested as well in an ongoing project concerning Herculanum. In an article in the scientific journal Nature Communications, a CNRS explained how a new, ultra-sophisticated imaging technique — called X-ray phase contrast tomography — could soon fulfill the dream of successive generations of philologists: cracking the secret of the Villa of the Papyri.

Located in Herculanum, the villa is believed to have been built for Piso, Julius Caesar's father-in-law and a great scholar of his time. It had a library — rediscovered 260 years ago — containing hundreds of papyri, some of which were probably only copies.

Buried with the eruption, some of these sealed scrolls became fossilized in the layers of volcanic matter. But until now, they resisted every attempt made to probe them with X-rays. With this new process, these obstinately silent treasures may finally reveal themselves.