Layer cake: The top image shows a digital recreation of Agur Wat, with elevation derived collected by LIDAR; the bottom image shows the raw LIDAR digital terrain model, with red lines indicate modern linear features including roads and canals.
Airborne laser scanning has revealed the remnants of a vast urban structure in the vicinity of Angkor Wat, a famous temple in Cambodia. The study, which will be published soon in the journal PNAS, follows a previous one that showed Angkor Wat to have been one of the world’s most complex preindustrial cities.
Light Detection and Ranging (LIDAR) is making it easier for archeologists to explore human settlements in tropical vegetation; previous LIDAR work has found evidence of new cities in Central America (see “A Lost City, Found With Lasers”), as well as further enhancing the layout of known settlements such as the Mayan city of Caracol.
For the new study, the researchers used a LIDAR setup emitting up to 200,000 laser pulses each second from a helicopter. Amazingly, the entire operation for the data collection spanned just 2 days in April 2012 for a total 20 hours of flight time, capturing imagery that would have taken many years to assemble from the ground, if at all. The LIDAR analysis also appears to have discovered what could be an older city beside Angkor Wat.
The study has revealed new canals, temples, and still unidentified manmade features, confirming a metropolitan area that housed many thousands of people, much as the Giza Plateau Mapping Project is doing for cities surrounding the Pyramids’ construction in Egypt.
As LIDAR technology gets cheaper, it will accelerate our understanding of early human settlements from the lingering geographic footprints we left, traces which can be almost as shallow as a footprint itself. As the authors write in their PNAS paper: “LIDAR technology has recently matured to the point where it has become cost-effective for archaeologists…with sufficient accuracy and precision to identify archaeological features of only a few centimeters in size.”