Synthetic TDR Measurements for TEM and GTEM Cell Characterization

This paper describes the main features of the timedomain reflectometry (TDR) measurement technique and, in particular, the TDR analysis performed using a proper operating mode of the vector network analyzer (VNA), which is called synthetic TDR. Furthermore, some results of reflection measurement, which aim to characterize the impedance behavior of transverse electromagnetic (TEM) and gigahertz TEM cells by means of a commercial VNA in time-domain mode, are presented

A FUSION-BASED WORKFLOW FOR TURNING SLAM POINT CLOUDS AND FISHEYE DATA INTO TEXTURE-ENHANCED 3D MODELS

Abstract. Mobile mapping systems are increasingly developing ad hoc solution and integrated approaches for rapid and accurate 3D digitization in different operating environments belonging to built heritage assets. The use of emerging compact, portable and low-cost solution for imaging and ranging well fits in the purposes of mapping complex indoor spaces especially for narrow and underground ones (tunnels, mines, caves and ancient spaces), that are very challenging contexts in which to experiment integrated technological solutions and tailored workflows. In these cases, the main key issues are generally the difficulty in the seamless positioning and the complete and successful metric-radiometric content association in metric surface, due to the reduced manoeuvring space and complex lighting conditions. The prevalent goals for which the 3D digitization could be conceived are, beyond the accurate metric documentation, the analysis of mutual relations of volumes in complex structures, the virtual reconstruction and navigation of spaces with reduced accessibility for dissemination aims. The new SLAM-based positioning solutions implemented in some recent portable systems for indoor/outdoor mapping are increasingly developing and favoured by geometric features extraction algorithms even in traveling through complex and irregular environments. In parallel, the possibility to exploit the advances in digital photogrammetry algorithms for image matching and dense reconstruction using action-cam, compact and fisheye cameras allows to deploy investigation solutions even in complex environments at first sight impossible to map by photogrammetric approach. Here within the F.I.N.E. benchmark in the site of the San Vigilio Castle (Bergamo) and the "nottole" tunnels, a fusion-based workflow is proposed. It is focused on the purposes of providing radiometrically enriched 3D data from the possibility to colourized ZEB point cloud and a textured mesh surfaces with an oriented image block, taking care of the time processing steps optimization

GEOMATIC CONTRIBUTION FOR THE RESTORATION PROJECT OF THE VALENTINO CASTLE GREEN ROOM. FROM DATA ACQUISITION TO INTEGRATED DOCUMENTATION

In the framework of restoration operations, valuable assistance can be supplied from innovative techniques and methods developed in the field of Geomatics. Over the years, this continuous collaboration has produced synergistic and interdisciplinary results that have been successfully contributing to heritage conservation and valorisation. In the case of the current research, thorough multisensory investigations have been performed in order to provide a deeper knowledge of the Green Room of the Valentino Castle in Turin and to support the planning of the future restoration works that will involve this valuable asset. In the framework of this experience, four LiDAR systems have been employed in order to evaluate the different results obtainable from the sensors. Additionally, a complete photogrammetric close-range survey has been carried out, and some tests were completed using a hyperspectral camera. The workflow followed during the current research is described in this paper, and a comparison between the obtained outputs is proposed, focusing on the characteristics of these metric products, useful and sometimes necessary in the framework of the restoration project. Besides, some considerations on the advantages and the issues connected with the use of these reality-based data as a starting point for HBIM (Heritage Building Information Modeling) model generation are proposed, along with some observations about the potentialities of a photogrammetric co-registration approach using spectrum technologies for deterioration/decay detection and monitoring of heritage

Challenging multi-sensor data models and use of 360 images. The Twelve Months Fountain of Valentino park in Turin

The cultural heritage and the ways in which it is today studied and analysed as well as disseminated and enhanced for the purposes of conservation, requires high attention in the choice of 3D survey and modelling methods. This manuscript investigates the possible integrations and fusion of methods and data, among the vast availability of image and range based systems, especially in the sphere of low cost techniques, which in the context of heritage documentation makes the whole and complex process of conservation more sustainable. The investigation is carried out on a historical fountain that includes a quantity of cultural values and the need to document its context: its location in the historical Valentino of Turin park, its architectural values and the geometry of the complex typically related to the tastes of the late XIX century that consist in the extreme refinement of the statuary complexes and the underground portion with the technological equipment for the activation of the water games. Basically, it will be possible to appreciate solved issues and permanent criticalities derived from the integration of close range and UAV photogrammetry techniques in addition to the LiDAR survey, both classic from a fixed position, and in the portable scanner mode, based on SLAM technology

Multitemporal 3D modelling for cultural heritage emergency during seismic events: Damage assesment of S. Agostino church in Amatrice (RI)

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.<br><br> 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 - <a href="http://areeweb.polito.it/direct/"target="_blank">http://areeweb.polito.it/direct/</a>) 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

UAV strategies validation and remote sensing data for damage assessment in post-disaster scenarios

The recent seismic swarms, occurred in Italy since August 2016, outlined the importance of deepen Geomatics researches for the validation of new strategies aimed at rapid-mapping and documenting differently accessible and complex environments, as in urban contexts and damaged built heritage. In the emergency response, the crucial exploitation of technological advances should obtain and efficiently organize high-scale reliable geospatial data for the early warning, impact, and recovery phases. Fulfilling these issues, among others, the Copernicus EMS, has played by now an important role in immediate and extensive damage reconnaissance, as in the case of Centre Italy. Nevertheless, the use of remote sensing data is still affected by a problem of point-of-view, scale and detectable detail. Nadir images, airborne or satellite, in fact, strongly limited the confidence level of these products. The subjectivity of the operator involvement is still an open issue, both in the first fieldwork assessment, and in the following operational approach of interpretative damage detection and rapid mapping production. To overcome these limits, the introduction of UAV platforms for photogrammetric purposes, has proven to be a sustainable approach in terms of time savings, operators’ safety, reliability and accuracy of results: the nadir and oblique integration can provide large multiscale models, with the fundamental information related to the façades conditions. The presented research, conducted within the Central Italy earthquakes events, will focus on potentialities and limits of UAV photogrammetry in the two documented sites: Pescara del Tronto and Accumoli. Here, the aim is not limited to describe a series of strategies for georeferencing, blocks orientation and multitemporal co-registration solutions, but also to validate the implemented pipelines as a workflow that could be integrated in the operative intervention for emergency response in early impact activities. Thus, it would be possible to use this 3D metric products as a reference-data for significative improvements of reliability in typical visual inspection and mapping, flanking the traditional nadir airborne- or satellite-based products. The UAV acquisitions performed in two damaged villages are displayed, in order to underline the implication of the spatial information embedded in DSM reconstruction and 3D models, supporting more reliable damage assessments