Airborne LiDAR supporting Archeology

ONe-flight-hour vs years of ground excavation!

As noticed in the past years when Angkor temple extensions were discovered in Cambodge, Airborne LiDAR is now a real help for archeologists. IMAO experienced it for some archeology companies, acquiring LiDAR data and photos. One of those projects was for EVEHA, an french company, over an hypothetical Gallic Oppidum in the South of France.

Efficient time saving

EVEHA mission was to conduct archæological excavations in order to reconstruct a part of the territory history. IMAO acquired a total of 3 hectares at the height of 400m AGL for an average LiDAR density of 14 pts/m2 and a 10cm GSD vertical photography.

The accuracy of the altimetric and georeferenced surveys made possible a high topographic restitution under forest cover and facilitated paths and backfill areas recognition: even the terraced vines culture was easily identified. One-flight-hour was enough to obtain the results that would have taken years of excavations to obtain.

Great details discovered

Some words from Fabien Loubignac, archæology project manager at EVEHA:
"At the beginning, we were looking for a possible bulwark on the site of the Gallic Oppidum. We had no visibility by foot to see the wall because of the high forested area. "

These surveys have contradicted suppositions about a potential oppidum on the top of the site, even if signs of fortifications have been found on the «Pradel», a symetrical mountain on the other side of the Dordogne river. It was a crucial discovery.

"We made the stratigraphy thanks to the LiDAR accuracy. It means chronologically relate the different vestiges, differentiate walls and paths which follow the levels curves...  We had many other surprises! Just behind the site, we discovered some mines, probably gold or galena, dated from the Gallic period. Also dry torrents and very large lines (7m deep)... Finally a set of paths all around the mines, up and down, like an alluvial cone, a kind of giant flush for washing the quartz vein. All this details had only been partially overview before."

Already operated on several archeological sites in France since 2007, the LiDAR technology has evolved from its beginnings to the efficient technology now used (Riegl LMS-Q680i and LMS-Q780). 

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TECHNICAL SPECIFICATIONS:

Superficie: 3 ha

Sensor LiDAR: LM6800 (RIEGL-IGI)

Sensor Photo: H60-35mm 

Imagery GSD: 10cm 

LiDAR density: 14pt/m2

 

Digital Surface Model

Digital Terrain Model