Czech Scientists and Divers Create 3D Model of Chýnov Cave
In May this year, Czech divers and geodesists (scientists who map geological formations in great detail) created - for the first time in Europe - a 3D map of a flooded cave system.
Since 2017, divers Petr Chmel and Mejla Dvořáček have been collaborating with geophysicist Jiří Šindelář to create a detailed map of Chýnov Cave, located in the Tábor region of the Czech Republic, approximately 100km south of Prague. The cave was first discovered during mining operations in 1863 and opened to the public five years later as a tourist attraction. It wasn't until the 1980s that speleologists found a deeper, permanently flooded part of the cave.
To create the 3D model, Petr and Mejla filmed the interior of the cave from a variety of different angles, with the resulting footage composited together using videogrammetry. The process was much more challenging than it sounds, as the camera had to be kept motionless while filming in order to facilitate the subsequent image processing, and the cave itself is a challenging environment to dive.
'The Chýnov Cave is complex in shape, very muddy and the deepest parts are accessible through a restricted space which is connected to a very low corridor,' said Petr Chmel. 'The recording could only be accomplished en route to the cave as there was zero visibility on the return.'
The expedition was led by Jiří Šindelář, a geophysicist from the Archaeological Institute of the Czech Academy of Sciences, together with Geo-cz, specialists in non-destructive exploration technologies.
'Usually, the diver only has around 25 minutes to get back to safety so our task was to make a detailed map of the cave within a limited amount of time,' said Šindelář. 'We modified the technologies used for the documentation of [land-based] archaeological sites for the divers, and in one twenty-minute dive, we were able to scan 200 meters of the cave using this method.'
The three-dimensional model of the cave will be used for further explorations and, since the Chýnov Cave provides water to the nearby Chýnov village, the technology could prove a valuable resource for research into underground water sources. 'The Chýnov cave system is really a complex labyrinth with several different layers, said František Krejča from the Chýnov Cave Administration. 'We knew that if the scanning proved to be successful, it could be used for other flooded spaces as well.'