Rapid and low-cost photogrammetric survey of hazardous sites, from measurements to vr dissemination

In the field of geomatics, the development of 3D surveying techniques that can produce dense point clouds and high-resolution three-dimensional models has opened the possibility of using these techniques to generate digital replicas of a given asset to be used in contexts of cultural promotion or entertainment.These non-traditional applications have been made easier by the spreading of low-cost but fast surveying techniques, allowing them to be used in contexts or projects with fewer resources. Close-range photogrammetry is nowadays the cheapest, most flexible, and fastest technique that can be used to produce high-resolution and high-quality digital copies of reality. In this paper, we present an application of the Ant3D multi-camera system, a novel photogrammetric device designed for the rapid 3D surveying of sites characterized by poor accessibility and narrow spaces. The paper describes the three-dimensional acquisition of underground tunnels in a hazardous abandoned mining site. The digitalisation work aims to create 3D models to be experienced safely in a virtual- or augmented- reality immersive navigation of the site for cultural promotion. A workflow is proposed to turn raw reality-based 3D models into refined and efficient 3D assets that can be exploited in a game engine. Applications for mobile devices, desktop, and VR headsets, using the produced 3D assets are described.