A Prompt Methodology to Georeference Complex Hypogea Environments

Abstract

ABSTRACT:Actually complex underground structures and facilities occupy a wide space in our cities, most of them are often unsurveyed; cable duct, drainage system are not exception. Furthermore, several inspection operations are performed in critical air condition, that do not allow or make more difficult a conventional survey. In this scenario a prompt methodology to survey and georeferencing such facilities is often indispensable. A visual based approach was proposed in this paper; such methodology provides a 3D model of the environment and the path followed by the camera using the conventional photogrammetric/Structure from motion software tools. The key-role is played by the lens camera; indeed, a fisheye system was employed to obtain a very wide field of view (FOV) and therefore high overlapping among the frames. The camera geometry is in according to a forward motion along the axis camera. Consequently, to avoid instability of bundle adjustment algorithm a preliminary calibration of camera was carried out. A specific case study was reported and the accuracy achieved.

Three-Dimensional Survey of Guattari Cave With Traditional and Mobile Phone Cameras

“…On the other hand, the use of photogrammetric methodology, in particular the SfM (Structure from Motion) algorithms, has proven remarkable robustness and versatility in narrow environments, particularly when fast measurements are necessary and very high precision is not required. In the papers by Troisi et al (2017), Perfetti et al, (2017) and Alessandri et al (2019), the mapping and the modeling of hypogea have been attained by the use of a camera equipped with fisheye lens. The latter is suggested when the length of the environment prevails on the other two dimensions (e.g.…”

Integrated Survey for Tensional Analysis of the Vault of the Church of San Nicola in Montedoro

“…To date, the panorama of the most widespread solutions and technologies for high-resolution three-dimensional digital surveying in the field of Cultural Heritage includes technologies based on active sensors (range-based), such as laser scanning, and those using passive sensors (image-based), such as high-resolution digital photogrammetry [Blais 2004;Remondino -El Hakim 2006;Guidi et al 2010;Manferdini -Remondino 2010;Vosselman -Maas 2010;Remondino 2011;Pirotti et al 2013] integrated with automatic image processing methods, such as Structure from Motion [Snavely et al 2006;Vergauwen -Van Gool 2006;Agarwal et al, 2009;Barazzetti et al 2010;Del Pizzo -Troisi 2011;Troisi et al, 2017;Alessandri et al,2019].…”

Testing Different Survey Techniques to Model Architectonic Narrow Spaces

“…It allows to limit the number of acquisitions, namely 287, and consequently save time both during the campaign and the elaboration (Troisi et al, 2017). The survey, using fisheye photogrammetry, was carried out by two operators: the camera operator whom moved through the rooms focusing on repeating a well-defined capturing geometry, and the lights operator whom focused on carrying, placing and orienting three speed-lights to light up the environment.…”