July 2, 2014

National Geographic Explorers Take To China’s Caves For Ambitious 3D Laser Scanning Project

Brett Smith for - Your Universe Online

Using 3-D laser scanning technology, a team of explorers has developed a Google Earth-style map of some of the largest caves in the world located in southeast China. The scans and a virtual tour of the caves are featured in the newest issue of National Geographic and available on the publications website.

“It’s a brilliant technique, which has only just been started to be used in caves, and it’s almost uniquely applicable in cave because in caves – you cannot see unless you’ve got an extremely large light,” team member Peter Smart, a geography professor at the University of Bristol, told National Geographic in a video interview.

[ Take the 3D Tour ]

To generate their three-dimensional renderings, the explorers traveled to an area of southeastern China that has the world's greatest density of eroded topography known as karst. For over 600 million years, this area was covered by a sea and during that time it built up miles-thick tiers of sediments, including limestone. Uplift and deterioration of the geological formation created the stone towers, sinkholes and immense caverns that can be seen today.

For their caving expedition, the team lugged bags loaded with laptops, batteries, and a rented 3-D laser scanner worth over $100,000. Once inside the caves, modern technology can record what the eye cannot. The team spent about one month in at least three of the largest chambers on the planet, switching on the scanner and assessing them precisely for the very first time.

[ Watch the Video: Climbing China’s Incredible Cliffs ]

The cave known as Hong Meigui was one of the most prominent caves mapped by the team and was only first explored in 2001 by foreign cavers. Many caves in southern China have a human history that includes the pursuit of chi, or life energy, which the karst areas were thought to have in abundance.

Hong Meigui is thought to be about the size of nine football fields and ranked eighth on a highly-reputable 2012 list of the world’s largest known cave rooms, behind other caves in Malaysia, Spain, and Belize.

To set up the scanning station, the team would set up a tripod using a level, orient the scanner using a compass and attach a laptop via a blue-green Ethernet cable. Writing for the National Geographic magazine, journalist Natalie Funk said the researchers would then press a button on the scanner and “suddenly it comes alive, its head silently revolving as the team seems to hold its collective breath.”

“Three minutes later the results appear on (team member Daniela) Pani’s laptop,” Funk continued. “The rendering is in black and white and low resolution. But it is stunning. There, as we crouch in the dark in the mud, staring at the bright screen, Pani flies us through the virtual cave—and I can finally see where I am. It’s an out-of-body experience.”

Funk told Pani the 3-D model reminds her of Google Earth.

“It’s like The Matrix,” Pani replied.

Funk also described the mapping of a similar limestone cave dubbed Titan.

“IF THERE IS A PERFECT CAVE for the fledgling art of subterranean laser scanning, Titan is it,” she wrote. “At the center of its massive chamber, slopes covered with rubble and pockmarked with pools creep relentlessly up to twin, 50-foot stalagmites that sit on the very peak of an underground mountain. Place the scanner atop the big one on the right, and you can take in almost all of Titan—about 13 acres, an area slightly larger than Hong Meigui—in a single 360-degree sweep.”

Cover image (below) credit National Geographic


FOR THE KINDLE: The History of 3D Printing: redOrbit Press