Historical documents represent a significant part of the world cultural heritage and need to be preserved from physical deformation due to ageing. The restoration of fragile documents requires economic resources that are often limited to only preserve the integrity of exceptional and highly valuable historical records. On the other hand, regeneration of ancient documents in digital form is a useful way to preserve them regardless of the material they are made of. In addition, the digitization of historical cartography allows creating a valuable dataset for a variety of GIS applications as well as spatial and landscape studies. Nonetheless, historical maps are usually deformed, and a contact-scanning process could damage them because this method requires planar positioning of the map. In this regard, photogrammetry has been used successfully as a non-invasive method to digitize historical documentation. The purpose of this research is to assess a low-cost and highly flexible strategy to digitize historical maps and documents through digital photogrammetry using low-cost commercial off-the-shelf sensors. This methodology allows training a wider audience of cultural heritage operators in digitizing historic records with a millimeter-level accuracy.

In the framework of built heritage monitoring techniques, a prominent position is occupied by thermography, which represents an efficient and non-invasive solution for these kinds of investigations, allowing the identification of phenomena detectable only in the non-visible range of the electromagnetic spectrum. This is of extreme interest, especially considering the possibility of integrating the radiometric information with the 3D models achievable from laser scanning or photogrammetric techniques, characterised by a high spatial resolution. This paper aims to illustrate how combining different geomatics techniques (in particular, by merging thermal images, laser scanning point clouds, and traditional visible colour photogrammetric data) can efficiently support historical analyses for studying heritage buildings. Additionally, a strategy for generating HBIM models starting from the integration of 3D thermal investigations and historical sources is proposed, concerning both the multi-temporal modification of the volumes of the building and the individual architectural elements. The case study analysed for the current research was the Palacio de Colomina in Valencia, Spain, a noble palace—now the headquarters of a university—that, during the last few centuries, has been subjected to considerable transformations in terms of rehabilitation works and modification of its volume.

In the wide scenario of heritage documentation and conservation, the multi-scale nature of digital models is able to twin the real object, as well as to store information and record investigation results, in order to detect and analyse deformation and materials deterioration, especially from a structural point of view. The contribution proposes an integrated approach for the generation of an n-D enriched model, also called a digital twin, able to support the interdisciplinary investigation process conducted on the site and following the processing of the collected data. Particularly for 20th Century concrete heritage, an integrated approach is required in order to adapt the more consolidated approaches to a new conception of the spaces, where structure and architecture are often coincident. The research plans to present the documentation process for the halls of Torino Esposizioni (Turin, Italy), built in the mid-twentieth century and designed by Pier Luigi Nervi. The HBIM paradigm is explored and expanded in order to fulfil the multi-source data requirements and adapt the consolidated reverse modelling processes based on scan-to-BIM solutions. The most relevant contributions of the research reside in the study of the chances of using and adapting the characteristics of the IFC (Industry Foundation Classes) standard to the archiving needs of the diagnostic investigations results so that the digital twin model can meet the requirements of replicability in the context of the architectural heritage and interoperability with respect to the subsequent intervention phases envisaged by the conservation plan. Another crucial innovation is a proposal of a scan-to-BIM process improved by an automated approach performed by VPL (Visual Programming Languages) contribution. Finally, an online visualisation tool enables the HBIM cognitive system to be accessible and shareable by stakeholders involved in the general conservation process.

Keywords: UAV photogrammetry, multi-temporal model, structural assessment, seismic emergency, Cultural Heritage One of the challenging purposes that must be undertaken by applied geomatics, is the need of monitoring by documenting continuously over time the evolution of urban spaces. Nowadays, this is a subject of great interest and study, mainly in case of sudden emergency events that implicate urban areas and specific historical buildings of our heritage. The newest Geomatics technique solutions must enable the demands of damage documentation, risk assessment, management and data sharing as efficiently as possible, in relation to the danger condition, to the accessibility constraints of areas and to the tight deadlines needs. In August 24^th 2016, the first earthquake hit the area of central Italy with a magnitude of 6.0; since then, the earth never stop shaking in a wide area in the middle of Italy. On 26^th and 30^th of October, two other big seismic events were recorded (magnitude 5.9 and 6.5) and the already damaged built heritage were struck again. Since the beginning of the emergency all the available resources (human and material) were deployed and the world of researchers is trying to furnish an effective contribute as well. Politecnico di Torino, in coordination with the national institutions, is deploying people, expertise and resources. The geomatics research group and the connected Disaster Recovery team (DIRECT - http://areeweb.polito.it/direct/) is part of this process and is working in deep contact and collaboration with the Remotely Piloted Aircraft Systems (RPAS) group of the Italian Firefighter. Starting from the first earthquake the late medieval religious complex of S. Agostino has been carefully monitored and detected, using a multi-perspective oblique imagery strategy with the aim to achieve 3D aerial and terrestrial models, in a multi-temporal perspective concerning three different time situation.

The recent developments of passive sensors techniques, that have been able to take advantage of the technological innovations related to sensors technical features, sensor calibration, the use of UAV systems (Unmanned Aerial Vehicle), the integration of image matching techniques and SfM (Structure from Motion) algorithms, enable to exploit both thermal and optical data in multi-disciplinary projects. This synergy boost the application of Infrared Thermography (IRT) to new application domains, since the capability to provide thematic information of the analysed objects benefits from the typical advantages of data georeferencing and metric accuracy, being able to compare results investigating different phenomena.This paper presents a research activity in terrestrial and aerial (UAV) applications, aimed at generating photogrammetric products with certified and controlled geometric and thematic accuracy even when the acquisitions of thermal data were not initially designed for the photogrammetric process. The basic principle investigated and pursued is the processing of a photogrammetric block of images, including thermal IR and optical imagery, using the same reference system, which allows the use of co-registration algorithms. Such approach enabled the generation of radiance maps, orthoimagery and 3D models embedding the thermal information of the investigated surfaces, also known as texture mapping; these geospatial dataset are particularly useful in the context of the built Heritage documentation, characterised by complex analyses challenges that a perfect fit for investigations based on interdisciplinary approaches.

One of the last and more pressing requests to the researchers working in the field of Geomatics is to research, validate, and propose new strategies for the rapid mapping of different contexts, with low-cost solutions. The continuous implementation of image-matching algorithms and their use in structure from motion (SfM) software allow using new sensors and implementing new strategies for the production of 3D models starting from an image-based approach. In the last years, another central issue for the researchers has been related with the documentation of cultural heritage (CH) artifacts using different sensors and techniques. In the experience presented in this paper, the attention was focused on these two central aspects: a test of a commercial off-the-shelf (COTS) steadicamera for the rapid 3D documentation of two cultural heritage artifacts was proposed. The two sites chosen to evaluate this mass market sensor were as follows: the Basilica of San Nicola (Tolentino, MC, Marche Region, Central Italy) and the Castello del Valentino (Torino, TO, Piedmont Region, North Italy). The metric products obtained with the Steadicam were compared with more consolidated techniques such as close-range photogrammetry (CRP) and terrestrial laser scanner (TLS). The products derived from the different techniques were then evaluated and compared, and an overall assess of the use of this new solution was made.