PARIS • When the Islamic State in Iraq and Syria (ISIS) group was about to be driven out of the ancient city of Palmyra in March, Mr Yves Ubelmann got a call from Syria's director of antiquities to go over in a hurry.
An architect by training, Mr Ubelmann, 36, had worked in Syria before the country was engulfed by war.
But now there was special urgency for the kind of work his youthful team of architects, mathematicians and designers did from their cramped offices in Paris: producing digital copies of threatened historical sites.
Palmyra, parts of it already destroyed by the Islamist militants who deemed these monuments idolatrous, was still rigged with explosives.
So he and Mr Houmam Saad, his Syrian colleague, spent four days flying a drone with a robot camera over the crumbled arches and temples.
"Drones with four or six rotors can hover really close and register structural details, every crack and hole, and we can take very precise measurements," said Mr Ubelmann, who founded the company Iconem.
"This is the stuff architects and archaeologists need."
They need it in a new push for virtual preservation that scientists, archaeologists and others, like Mr Ubelmann, are compiling on a large scale.
The records could be used to create computer models that would show how monuments and endangered historical sites might one day be restored, repaired or reconstructed.
Of special interest today are ancient sites in Syria and Iraq that have suffered from war, looting and ISIS.
"Palmyra was very difficult," Mr Ubelmann said. "The terrorists were uploading videos with them blowing up monuments and smashing statues to manipulate public opinion.
"We felt the best response was to magnify the pictures of these places and show their splendour and their importance to the culture. It became a war of images."
The latest front in that war is in the exhibition halls of the Grand Palais in Paris, where, till next Monday, many of the 40,000 images he and his team took at Palmyra have become the basis for displays.
Called Eternal Sites: From Bamiyan To Palmyra, the show aims to draw attention to the rising threats to global heritage.
French President Francois Hollande has taken a strong interest in the exhibition, condemning the deliberate destruction of patrimony by all sides as "war crimes". This past month, France offered US$30 million (S$43.5 million) towards a proposed US$100 million fund to protect sites as fighting abates, provide emergency storage for artefacts and eventually rehabilitate monuments.
At the Eternal Sites opening at the Grand Palais, Mr Hollande stressed that France was taking in more Syrian refugees; trying to protect monuments of great historical and cultural importance did not mean ignoring the suffering of the population.
"Should we be concerned about the patrimony?" he asked. "What is more important, saving lives or saving stones? In reality, these two are inseparable."