PRAGUE (REUTERS) - These specialists are off to make a 3D map of a cave, using technology developed by Geo-CZ - a company which specialises in mapping historical and archaeological sites.

"For the 3D mapping we are using a special camera holder which holds at least two cameras used for 3D mapping. We use very powerful wide-angle diver's lights. We have to go through the main cave corridor smoothly to follow the shape of the cave and we have to cover the side corridors of the cave which are not properly lit. The advantage of this technology is that we collect the data and then it's processed on a computer in the office. We don't have to describe the underwater parts of the cave by hand anymore," said cave diver Petr Chmel.

The Czech company says its 3D maps are made using what is called "videogrammetry".

It is a technique most commonly used in the manufacturing industry.

They look at footage from hard to access terrains - like this flooded cave - and take measurements of the surroundings, which are then stitched into a 3D animation using computers.

"It is more detailed, more exact and most importantly for us, by using 3D imagery we can really understand the connections between the (cave's) corridors and within the whole (cave's) system. The system simply fits it together. We can get much more information from this - about the cave's origin, its formation and development as well as its morphology, so how the cave actually looks," said Chynov cave specialist Frantisek Krejca.

It also means that only one person is required to don a wet suit and helmet for filming, making exploration and mapping faster and less dangerous.