Lasers are driving a revolution in archaeology - LiDAR technology has helped archaeologists find a lost Mayan city along with other ancient sites, transforming how researchers approach unsurveyed land :

What did past civilizations leave behind? For archaeologists, that question can be difficult to answer. Remnants of buildings and other sites can be almost impossible to spot. Blame the ravages of time and nature, which can cover old walls and foundations in trees, vegetation, water, soil and more. Then turn to LiDAR, one of archaeology’s most exciting modern tools. Light detection and ranging, or LiDAR, has changed the face of archaeology by making it possible to measure and map objects and structures that might otherwise remain hidden.

Modern LiDAR relies on laser sensors that are deployed from air or via handheld units. As lasers shine on the area to be mapped, they emit brief pulses of light. The amount of time it takes for those pulses to reflect back to instrument is measured, and each measurement is plotted using GPS. Computers then use that data to construct a 3D map of the area. One of LiDAR’s strengths is how well it can pinpoint tiny surface anomalies that indicate small sites like graves or big ones like sunken cities. But LiDAR has its limitations: It can’t reach beneath ground, and trees in densely wooded areas can sometimes cause features to be missed. Still, its accuracy is prized by archaeologists, who use it to map topography, plan excavations, and spot archaeological sites they’d never be able to see with naked eye. It is relatively quick and inexpensive compared to archaeological excavations, and can offer a high-level view not accessible to researchers who focus on just a few sites on the ground.

The technology was invented for military use, but was first applied widely by meteorologists intent on studying clouds. The first LiDAR prototype was built in 1961 by Hughes Aircraft Company, which had built first laser a year earlier. One of earliest beneficiaries of LiDAR was United States’ space program; the technology was used to map the moon during 1971 Apollo 15 mission. Today, LiDAR is more down to earth, and is used to find archaeological clues both on the surface and in the water. Remote sensing has been credited with an “archaeology revolution” that is shifting the way researchers think about their work. In the early 2010s, archaeologists looking for evidence of hard-to-find Maya sites were astonished when LiDAR revealed a lost Maya city.

In another case, researchers used LiDAR to spot more than 20,000 archaeological features of a seemingly minor site in Mexico that actually had been home to an ancient city. “In 45 minutes of flying, LiDAR team accomplished a decade’s worth of archaeological survey,” said anthropologist Christopher Fisher in a release. Bathymetric LiDAR even revealed a Roman villa in Croatia. LiDAR doesn’t just reveal what is hidden: It can also document what has already been found. Technology is being used on the ground to map structures like the Notre Dame cathedral in Paris and Florence, Italy’s Salone dei Cinquecento.

📷 : Titan LiDAR data maps the forest canopy above Tikal and what is hidden below, at a unprecedented level of detail.

© National Geographic

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