Image-based virtual tours and 3D modeling of past and current ages for the enhancement of archaeological parks: The VisualVersilia 3D project

The research project VisualVersilia 3D aims at offering a new way to promote the territory and its heritage by matching the traditional reading of the document and the potential use of modern communication technologies for the cultural tourism. Recently, the research on the use of new technologies applied to cultural heritage have turned their attention mainly to technologies to reconstruct and narrate the complexity of the territory and its heritage, including 3D scanning, 3D printing and augmented reality. Some museums and archaeological sites already exploit the potential of digital tools to preserve and spread their heritage but interactive services involving tourists in an immersive and more modern experience are still rare. The innovation of the project consists in the development of a methodology for documenting current and past historical ages and integrating their 3D visualizations with rendering capable of returning an immersive virtual reality for a successful enhancement of the heritage. The project implements the methodology in the archaeological complex of Massaciuccoli, one of the best preserved roman site of the Versilia Area (Tuscany, Italy). The activities of the project briefly consist in developing: 1. the virtual tour of the site in its current configuration on the basis of spherical images then enhanced by texts, graphics and audio guides in order to enable both an immersive and remote tourist experience; 2. 3D reconstruction of the evidences and buildings in their current condition for documentation and conservation purposes on the basis of a complete metric survey carried out through laser scanning; 3. 3D virtual reconstructions through the main historical periods on the basis of historical investigation and the analysis of data acquired

Multi-sensors integrated system for landslide monitoring: critical issues in system setup and data management

This paper discusses critical issues related to the reliability of topographic monitoring systems such as ATS (Automated Total Stations), GNSS (Global Navigation Satellite System) and Ground Based InSAR focusing the attention on controlling the stability of networks infrastructure, which have influence on data correction procedures but are often taken for granted, and on integrating results in GIS (Geographic Information System), under a common reference framework and with respect to open-access ancillary data. The novelty of the paper lies in the demonstration of the efficiency obtained by a proper implementation of the system. Discussion makes reference to an active landslide by using ATS, GNSS and Ground Based InSAR in continuous and periodic mod

Dynamic Assessment of Masonry Towers Based on Terrestrial Radar Interferometer and Accelerometers

This paper discusses the performance of a terrestrial radar interferometer for the structural monitoring of ancient masonry towers. High-speed radar interferometry is an innovative and powerful remote sensing technique for the dynamic monitoring of large structures since it is contactless, non-destructive, and able to measure fast displacements on the order of tenths of millimeters. This methodology was tested on a masonry tower of great historical interest, the Saint Prospero bell tower (Northern Italy). To evaluate the quality of the results, data collected from the interferometer were compared and validated with those provided by two types of accelerometer-based measuring systems directly installed on the tower. Dynamic tests were conducted in operational conditions as well as during a bell concert. The first aimed at characterizing the dynamic behavior of the tower, while the second allowed to evaluate the bell swinging effects. Results showed a good agreement among the different measuring systems and demonstrated the potential of the radar interferometry for the dynamic monitoring of structures, with special focus on the need for an accurate design of the geometric aspects of the surveys

3D reconstruction of an underwater archaelogical site: comparison between low cost cameras

The 3D reconstruction with a metric content of a submerged area, where objects and structures of archaeological interest are found, could play an important role in the research and study activities and even in the digitization of the cultural heritage. The reconstruction of 3D object, of interest for archaeologists, constitutes a starting point in the classification and description of object in digital format and for successive fruition by user after delivering through several media. The starting point is a metric evaluation of the site obtained with photogrammetric surveying and appropriate 3D restitution. The authors have been applying the underwater photogrammetric technique since several years using underwater digital cameras and, in this paper, digital low cost cameras (off-the-shelf). Results of tests made on submerged objects with three cameras are presented: (c) Canon Power Shot G12, (c) Intova Sport HD e (c) GoPro HERO 2. The experimentation had the goal to evaluate the precision in self-calibration procedures, essential for multimedia underwater photogrammetry, and to analyze the quality of 3D restitution. Precisions obtained in the calibration and orientation procedures was assessed by using three cameras, and an homogeneous set control points. Data were processed with (c) Agisoft Photoscan. Successively, 3D models were created and the comparison of the models derived from the use of different cameras was performed. Different potentialities of the used cameras are reported in the discussion section. The 3D restitution of objects and structures was integrated with sea bottom floor morphology in order to achieve a comprehensive description of the site. A possible methodology of survey and representation of submerged objects is therefore illustrated, considering an automatic and a semi-automatic approach

Validation tests of open-source procedures for digital camera calibration and 3D image-based modelling

Among the many open-source software solutions recently developed for the extraction of point clouds from a set of un-oriented images, the photogrammetric tools Apero and MicMac (IGN, Institut G\ue9ographique National) aim to distinguish themselves by focusing on the accuracy and the metric content of the final result. This paper firstly aims at assessing the accuracy of the simplified and automated calibration procedure offered by the IGN tools. Results obtained with this procedure were compared with those achieved with a test-range calibration approach using a pre-surveyed laboratory test-field. Both direct and a-posteriori validation tests turned out successfully showing the stability and the metric accuracy of the process, even when low textured or reflective surfaces are present in the 3D scene. Afterwards, the possibility of achieving accurate 3D models from the subsequently extracted dense point clouds is also evaluated. Three different types of sculptural elements were chosen as test-objects and "ground-truth" data were acquired with triangulation laser scanners. 3D models derived from point clouds oriented with a simplified relative procedure show a suitable metric accuracy: all comparisons delivered a standard deviation of millimeter-level. The use of Ground Control Points in the orientation phase did not improve significantly the accuracy of the final 3D model, when a small figure-like corbel was used as test-object