Experiences from the Creation of a Virtual Tour through a Stalactite Cave with VR Gear

This paper describes the 3D survey of an Austrian stalactite cave and the derivation of a Virtual Reality (VR) tour through the data set with the Game Engine Unity. The survey of such a cave beholds many challenges like narrow passages, abstinence of light and scan obstructions in the large stalactite fields.
Documenting this huge cave-network required several scanning sessions since the year 2016.
The limitations of a cave survey have been overcome by the usage of a broad spectrum of sensors, geodetic total stations, different types of static terrestrial and kinematic laser scanners, SLR cameras and even DJI Mini drones.
However, the different surveying techniques deliver varying texture qualities and point accuracies which resulted in inhomogeneous 3D data. Combining these data sets in a common coordinate system and merging them into a single 3D mesh required a solid geodetic reference frame and postprocessing in commercial software products from the laser scanning industry, structure from motion solutions and applications from the entertainment sector.
The final 3D model is presented in a VR application as the complexity of the geometry exceeds the capability of the conventional 3D viewers. The user can move along the mesh, has to duck in narrow passages and handles a torch for the exploration of the dark underground. This way students and school pupils get an immersive impression of the dimensions of the cave while
they learn about the 3D survey.