Interesting projects were in abundance at the recent RIEGL LiDAR conferences in Hong Kong and Guangzhou, China, but cave explorers seemed to capture everyone’s attention. Andy Eavis and Richard Walters, of the British Caving Association, discussed their project during a user session in Hong Kong and also offered a keynote presentation at the start of the Guangzhou conference.

Eavis is a modern explorer. He loves discovering undocumented territory. “We’re cave explorers,” he said. “The group I work with has been exploring caves for nearly 50 years.” He said he first became interested in caving while he was at university and still caves with many of the same people he met then.

“I did have a proper job to raise money,” he said. “Exploring caves was simply a hobby. I got involved with really big caves, bigger caves than most people ever realized existed or could exist.”

Eavis has been to most large caves throughout the world. In the early 1970s, they went to Carlsbad Caverns in New Mexico, which, at the time, was considered to be the biggest cave room in the world, he said. In 1978, they organized an expedition to Borneo’s Deer Cave and Sarawak Chamber, which is “arguably the largest-known cave passage in the world.” Eavis said there is a cave in Vietnam on a similar scale but until they scan both of them, it’s impossible to know which one is larger.

He said they went back to Borneo in 1980 and “were in a space where the only thing we could see was the floor we were standing on, and little did we know, the thing we were exploring was the largest known cavity on Earth!”

The two previously recorded largest caves in the world could fit inside, Eavis said.

The group first came to China in 1982, to the city of Guilin in the southeast corner of the country. China allegedly contains the largest concentration of undocumented caves in the world. “It was very much a mecca for us to come and explore caves in China,” Eavis said. “The team members on that trip are still exploring caves today. We made contacts with some very, very god people. The scale of caves in China is extraordinary.”

For Eavis, the most exciting part of caving is that something bigger is almost certainly waiting to be discovered, and he hopes to be part of the team that does.

Laser scanning offers detailed documentation

“A man named Kevin Dixon introduced us to laser scanning in 2010,” Eavis said. “He came with us on one of our trips to Borneo with a scanner and we very slowly and laboriously scanned Deer Cave and Sarawak Chamber in Malaysia. That really got us on to the project of laser scanning. We’ve now embarked on an ongoing voluntary project as a hobby to laser scan these chambers.”

Richard Walters, a member of Eavis’ team, has been heavily involved in laser scanning the caves. “We’re trying to find the true nature of the biggest caves in the world,” he said. “To see what caves are really like. They are enormous black spaces when you’re standing there with your Riegl scanner in the middle of the night. The only thing you can see around you is the floor… until you get results from a scan.”

Walters is excited about laser scanning because the technology can capture what the human eye cannot.

“A cave we just discovered and explored recently is over 300 meters high. Just to give you an idea of scale, there are only four buildings in Hong Kong that are higher than that natural chamber we were exploring,” he said.

Walters discussed an expedition in 2013 funded by the National Geographic Society to the Miao chamber in China, which was thought to be the second largest cave in the world until they got there and measured it. They discovered it is the largest chamber by volume in the world, much larger than previously thought.

“One of the biggest things about scanning technology is it really helps us reveal the true nature of these caves in real time. It’s really quite fascinating stuff.”

Walters said new caves are being discovered all the time. In April, French cavers found a very large chamber in China that will shortly be on the list of largest caves in the world, he said.

Walters uses a Riegl VZ-400, which his team used for caving for the first time. He said it’s light enough to carry at about 21 pounds and has enough range (400 meters) for what they need to do. It also works with a range of software tools to process their information.

“The scanner has performed immaculately in quite difficult positions,” Walters said. “We are carrying it in rugged places—dirty, dusty, smelly—and it has performed absolutely perfectly. Another reason we chose the Riegl scanner is the process in the field is really quite simple. You just decide what you want to do, place it in the tripod, press a couple buttons and move on. And if one of us is tired or ill, someone else can take over that process very easily with little training. That’s very important on the ground since you can’t stay there forever. You have all these considerations to take into account. In a full day of scanning, we haven’t run out of power yet.

“Essentially, you can get results very quickly, which is extremely helpful.”

Walters said next for the team are caves in Iran, Oman, Belize and Mexico. “This will be the first time these caves have ever been surveyed consistently in 3D,” he said.

Boundaries not precise

Eavis was asked how they determine the boundaries of the chambers they scan since caves are irregularly shaped. Eavis said it can be difficult where to draw the boundary lines and what constitutes a cave chamber, but that is one of the issues that 3D scanning can help resolve. He said they have so far printed 3D models of four of the biggest chambers and are hoping to present a ranking of the top 10 world’s largest chambers by volume—with 3D models—at an international caving conference in 2017. The models help show the chamber’s boundaries in detail.

“We’re going to try and democratically come up with answers to what a chamber is,” he said. “How do you define what is the largest passage in the world and where do you put the limits on the chamber? That’s one of the things we are working on.”