Underwater imaging used to map prehistoric cave art

Underwater data and imaging company Fugro has been tasked with using their Geo-data technology to ‘preserve’ a very unusual site. 

The French Ministry of Culture has awarded Fugro a contract to scan the astonishing Cosquer Cave, located in the Urgonian limestone at Cap Morgiou near Marseille, France.

rising sea levels are erasing 177 cave paintings dating back to 27,000 BC

These cave paintings date back 27,000 years yet despite their longevity, time is of the essence: rising sea levels are gradually effacing the cave’s display of 177 exquisite and irreplaceable paintings and engravings.

Fugro will use their Geo-data scanning technology to create ‘a permanent record of huge cultural significance’.

How to scan cave paintings underground and underwater

In challenging conditions, and together with Immadras, a French professional diving company, Fugro will use the latest photogrammetric, 3D laser scanning and lighting technology to digitise and map the cave. The artwork above the surface is recorded in full colour and meticulous detail (0.1 mm resolution), and a lower resolution will used for the underwater section, which accounts for around two-thirds of the cavity. Fugro will then produce a highly accurate, georeferenced 3D model of the entire cave structure.

The data will provide invaluable insights for archaeological, paleontological and climatological researchers, and for future generations. Fugro will also model the landscape surrounding the entrance, 37 metres below sea level, as well as the narrow, 120-metre underwater access tunnel leading up to the cave.

It has involved a lot of diving. Bertrand Chazaly, Fugro’s Digital and 3D Expert conducted Fugro’s initial 3D survey in September 2010 and has since completed more than 70 dives in the cave system. The project will require a further 45 dives and a painstaking approach to avoid damaging the beautifully preserved cave. “Many of the paintings of horses and hands are perilously close to the rising water level,” said Chazaly.

“Fugro’s job is to map and record these precious works of art before they are lost forever, and to model the underwater structure. Archaeologists will then use our Geo-data to gain a better understanding of how prehistoric humans lived in the cave and the positioning of the various groups of paintings.”

The project is scheduled for completion early in 2022.