3D mapping of underground environments with a hand-held laser scanner

The development of several instruments and techniques for reality-based 3D survey provides for new effective and affordable solutions for mapping underground environments. Terrestrial laser scanning (TLS) techniques demonstrated to be suitable for recording complex surfaces in high resolution even in low ambient lightning conditions. TLS approaches allow to obtain millions of 3D points and very detailed representations of complex environments, but these normally required a very high number of stations. This paper presents the investigation and deployment of a hand-held laser scanning system, the GeoSlam Zeb1, for the fast 3D digitization of underground tunnels. This active hand-held device was employed in two different typologies of underground structures: the Grotta di Seiano (Fig.1 a-b), a 800 m long monumental passage used as entrance of a roman villa in Posillipo (Naples), and some military fortifications (Fig.1 c-d) built during the First World War (WWI) on the hills around Trento. In the first case study, owing to the length of the gallery and the lack of well-defined geometric features on its wall, errors in the alignment were expected. Consequently, the final alignment of the numerous acquired scans was verified. In the second part, the research is focused on suitable procedures for the final three-dimensional representation and visualization of complex underground passages, i.e. the military tunnels. Using an automatic classification procedure on the point-clouds, vegetation was removed and, through a manual segmentation approach, the rooms were classified according to their specific functions. In the paper, the results are critical presented and discussed

3D imaging for museum artefacts: a portable test object for heritage and museum documentation of small objects

3D colour image data generated for the recording of small museum objects and archaeological finds are highly variable in quality and fitness for purpose. Whilst current technology is capable of extremely high quality outputs, there are currently no common standards or applicable guidelines in either the museum or engineering domain suited to scientific evaluation, understanding and tendering for 3D colour digital data. This paper firstly explains the rationale towards and requirements for 3D digital documentation in museums. Secondly it describes the design process, development and use of a new portable test object suited to sensor evaluation and the provision of user acceptance metrics. The test object is specifically designed for museums and heritage institutions and includes known surface and geometric properties which support quantitative and comparative imaging on different systems. The development for a supporting protocol will allow object reference data to be included in the data processing workflow with specific reference to conservation and curation

EXPERIENCING THE INACCESSIBLE. A FRAMEWORK FOR VIRTUAL INTERPRETATION AND VISUALIZATION OF REMOTE, RISKY OR RESTRICTED ACCESS HERITAGE PLACES

Abstract. In order to be properly handed down, especially in particular conditions with a high rate of vulnerability, cultural heritage requires documentation and enhancement strategies. The case study presented in this paper is particularly critical not only for the conservation conditions, but especially for the environmental conditions: the Catacombs of San Vittorino have complex conditions of recovery, because of the nature of the artefact and because of the poor lighting of the main environments. For this particularity, a workflow was developed that, in order to achieve the creation of an immersive device navigable by digital viewers such as Oculus Rift or similar, required the start-up of shooting by laser scanning, and then treat the point cloud with different software, in order to obtain a satisfactory result that, in other contexts, could have started easily from a photogrammetric shooting.</p

INVESTIGATION OF THE UNDERGROUND BUILDING HERITAGE AND THE MECHANISM OF WATER FLOWING IN QANĀTS IN PALERMO THROUGH INNOVATIVE SURVEYING TECHNIQUES

The valorisation, protection and preservation policies for the underground building heritage are often difficult to implement due to an inadequate knowledge of hypogeal constructions. The complex and widespread underground structures of the vast “Cavo” Heritage (“horizontal wells”, “shelf wells” or “well tunnels”), so called qanāts, hidden underground and built over the centuries in Palermo, representing an evocative testimony to the history of water culture in the ancient city. Through the historical and constructive analyses and the implementation and development of measurement and 3D representation and visualization, first actions have been carried out. The paper will present the first results of the restoration project and the path of re-introduction in the fruition network of the qanāt “Gesuitico alto”, developed also in the field of “iHeritage. Mediterranean Platform for UNESCO Cultural Heritage” project, financed by ENI CBC MED Programme 2014-2020. The paper presents an experimentation of a procedural workflow of data acquisition, analysis and subsequent 3D virtual navigation of hypogeal environments. The methodology used is the SLAM with a last generation WMLS. The platform of virtual reality visualization, within UnReal Engine, allows the user to immerse and navigate in the anthropic environment by engaging it with a set of infographics that highlight the virtual visit

3D MODELING FOR ROCK ART DOCUMENTATION USING LIGHTWEIGHT MULTISPECTRAL CAMERA

This paper discusses the use of the lightweight multispectral camera to acquire three-dimensional data for rock art documentation application. The camera consists of five discrete bands, used for taking the motifs of the rock art paintings on a big structure of a cave based on the close-range photogrammetry technique. The captured images then processed using commercial structure-from-motion photogrammetry software, which automatically extracts the tie point. The extracted tie points were then used as input to generate a dense point cloud based on the multi-view stereo (MVS) and produced the multispectral 3D model, and orthophotos in a different wavelength. For comparison, the paintings and the wall surface also observed by using terrestrial laser scanner which capable of recording thousands of points in a short period of time with high accuracy. The cloud-to-cloud comparison between multispectral and TLS 3D point cloud show a sub-cm discrepancy, considering the used of the natural features as control target during 3D construction. Nevertheless, the processing also provides photorealistic orthophoto, indicates the advantages of the multispectral camera in generating dense 3D point cloud as TLS, photorealistic 3D model as RGB optic camera, and also with the multiwavelength output

Critical factors and guidelines for 3D surveying and modelling in Cultural Heritage

The 3D digitization of sites or objects, normally referred to “realitybased 3D surveying and modelling”, is based on 3D optical instruments able to deliver accurate, detailed and realistic 3D results. Nowadays many non-experts are facing the 3D world and its technologies (hardware and software) due to their easiness of use but a not correct use leads to wrong results and conclusions. The goal of the article is to critically report the 3D digitization pipeline with some Cultural Heritage examples. Based on our experiences, some guidelines are drawn as best practices for non-experts and to clearly point out the right approach for every goal and project

High-resolution digital 3D models of Algar do Penico Chamber: limitations, challenges, and potential

The study of karst and its geomorphological structures is important for understanding the relationships between hydrology and climate over geological time. In that context, we conducted a terrestrial laser-scan survey to map geomorphological structures in the karst cave of Algar do Penico in southern Portugal. The point cloud data set obtained was used to generate 3D meshes with different levels of detail, allowing the limitations of mapping capabilities to be explored. In addition to cave mapping, the study focuses on 3D-mesh analysis, including the development of two algorithms for determination of stalactite extremities and contour lines, and on the interactive visualization of 3D meshes on the Web. Data processing and analysis were performed using freely available open-source software. For interactive visualization, we adopted a framework based on Web standards X3D, WebGL, and X3DOM. This solution gives both the general public and researchers access to 3D models and to additional data produced from map tools analyses through a web browser, without the need for plug-ins

Lo spazio virtuale del passato. Documentazione, modellazione e fruizione virtuale del patrimonio archeologico. Il Parco Archeologico di Pausilypon.

L’archeologia, fondata su una cultura materiale da registrare, interpretare e trasmettere, è una disciplina essenzialmente visuale. La nascita di nuovi processi di produzione delle immagini rende il tema della visualizzazione archeologica, in particolare, sempre più centrale. L’introduzione delle tecnologie digitali nel campo del patrimonio culturale ha segnato, infatti, l’inizio di un processo di “virtualizzazione” della conoscenza e della conservazione dei beni. Nei sistemi di produzione della conoscenza della “Virtual and Cyber-Era”, l’immagine archeologica trova così una sua nuova dimensione, digitale, tridimensionale, poli-funzionale, virtuale ed interattiva. La tesi presenta il lavoro di documentazione e modellazione tridimensionale condotto nel Parco Archeologico di Pausilypon, presentando lo sviluppo di tour virtuali per la fruizione virtuale dei modelli digitali

Archaeology on the Apulian – Lucanian Border

The broad valley of the Bradano river and its tributary the Basentello separates the Apennine mountains in Lucania from the limestone plateau of the Murge in Apulia in South East Italy. For millennia the valley has functioned both as a cultural and political divide between the two regions, and as a channel for new ideas transmitted from South to North or vice versa depending on the political and economic conditions of the time. Archaeology on the Apulian – Lucanian Border aims to explain how the pattern of settlement and land use changed in the valley over the whole period from Neolithic to Late Medieval, taking account of changing environmental conditions, and setting the changes in a broader political, social and cultural context. There are three levels of focus. The first is on the results of a field survey (1996-2006) in the Basentello valley by teams from the Universities of Alberta, Edinburgh, and Bari, directed by the authors. The second concerns the discoveries of earlier field surveys in the late 1960s and early 1970s undertaken in connection with excavations on Botromagno near Gravina in Puglia. The third is a much broader synthesis of the results of recent scholarship using archaeological, epigraphic and literary sources to reconstruct an archaeological history of the valley and the surrounding area. The creation of a vast imperial estate at Vagnari around the end of the 1st century BC and its long-lasting impact on the pattern of settlement in the area is a significant theme in the later chapters of the book