Laser vision reveals hidden worlds
Mapping technology lets researchers see what the naked eye cannot
By
Stephen Ornes
May 1, 2015
In the ancient Maya city of Caracol, map-making can be treacherous. Jungles shroud this site in the Central American nation of Belize. Dense shrubs stand taller than a person’s head. They hide ruins that otherwise would be obvious. To reveal the city, archeologists must hack through the growth, using sharp blades called machetes. They step carefully to avoid critters like the fer-de-lance, a common viper with an often-fatal bite.Arlen and Diane Chase know these hazards well. These archeologists work at the University of Central Florida in Orlando. For three decades, the husband-and-wife team (who cut their wedding cake with a machete) also have patiently studied Caracol. Season by season, they and their team — and later, their children — have hacked and mapped, hacked and mapped.
Then, in April 2009, everything changed. That’s when lidar came to Caracol. Lidar stands for “light detection and ranging.” It’s a method of using lasers to create a map. And it revealed this part of the world in a whole new light.
For five days, a small Cessna airplane buzzed over Caracol and the surrounding region. Onboard, a device fired laser pulses at the ground. And not just a few: This machine sent billions of pulses streaming into the jungle.Some laser pulses vanished in the heavy tree cover. Many others bounced off leaves and returned to the plane. Still others reflected off of the ground or hidden stone structures. The lidar device recorded how long it took the echo of each pulse to return. The device used those bounce times to compute how far the light had traveled. In total, it recorded more than 4 billion measurements of the jungle terrain.
Back on the ground, computer programs turned those data into a detailed map of the site. The laser pulses revealed the contours of temples and other buildings, roadways and even terraced fields. It was as if lidar had peeled back the jungle to reveal much more of Caracol than anyone had seen since the Maya city went into decline more than 1,000 years ago.
Arlen Chase said that all at once he could “see” the jungle-covered ruins he and Diane had painstakingly charted over the decades. This map also turned up many other hidden archeological features. “I couldn’t stop looking at it,” he says. “It was mind-boggling.”
https://student.societyforscience.org/article/laser-vision-reveals-hidden-worlds
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