Archeologists make it their job to uncover the mysteries of the past, so we can better understand ourselves. Traditionally, archeology required spending of hundreds of man-hours poring over old documents and tromping through muddy fields to locate settlements and civilizations lost to time. Now, with LiDAR mapping, explorations that used to take years can now be accomplished in a matter of days.
LiDAR, which stands for Light Detection and Ranging, uses pulses of laser light to take measurements and generate a 3D map of an environment. After the unit sends out a laser pulse, a sensor on the instrument measures the amount of time it takes for each pulse to bounce back. As light moves at a constant speed, the LiDAR sensor is able to accurately calculate the distance between itself and the target. When the LiDAR receives data about the location of objects, it generates a point cloud. Point clouds look like a picture made up of a large amount of small dots. Each of these dots represents a data point collected by the LiDAR. These data points are then fed into slamming software, which combines the point cloud data into a 3D image of the objects and environment surrounding the LiDAR unit.
Locating Lost Civilizations with LiDAR
Locating lost civilizations and settlements begins with mounting LiDAR sensors, such as Velodyne’s Puck Lite, onto a small plane or a drone. The plane or drone is then flown over the area archeologists want to investigate. While airborne, the LiDAR unit bounces laser pulses off the ground to generate a map of its surface features. The 3D map reveals geometric patterns, mounds, and indentations that cannot be detected from the ground. When placed together on a 3D map, the patterns can reveal the shapes and outlines of ancient buried buildings, walls, water systems, gardens and roads.
The use of LiDAR mapping for archaeological research did not become popular until 2010, when Arlen and Diane Chase from the University of Central Florida used LiDAR to uncover a large swath of ruins near Caracol, an ancient Mayan city outside of Belize. Since then, LiDAR mapping technology has been used to make even more historic findings.
In 2016 Matthew Liebmann, an archaeologist at Harvard, used LiDAR technology to discover the ruins of a village previously inhabited by Native Americans in the Jemez Mountains of New Mexico. Liebmann used his LiDAR to map and count how many buildings and rooms were in each settlement to approximate the village population. He then counted the rings inside of trees now growing inside of those housing structures to approximate how long ago the villages were inhabited.
The biggest news in the LiDAR archeology world, however, was the uncovering of several cities in the jungle surrounding Angkor Wat. A LiDAR mapping survey was conducted over a three-year period by the Cambodian Archaeological LiDAR Initiative (CALI). A scan was made of over 2,000 square kilometers of Cambodian jungle in an effort to learn more about the medieval Khmer empire. The sheer size of the cities being uncovered seem to indicate that the Khmer empire was the largest of the 12th century and could potentially rewrite Asia’s history.
Combined with the brilliant minds of archeologists and their hard working teams, LiDAR mapping has the ability to help reclaim what time has buried beneath the earth. Everyday, new discoveries are made that bring us closer to understanding the world we live in.