Hand Held 3D Scanning for Cultural Heritage: Experimenting Low Cost Structure Sensor Scan.

In the last years 3D scanning has become an important resource in many fields, in particular it has played a key role in study and preservation of Cultural Heritage. Moreover today, thanks to the miniaturization of electronic components, it has been possible produce a new category of 3D scanners, also known as handheld scanners. Handheld scanners combine a relatively low cost with the advantage of the portability. The aim of this chapter is two-fold: first, a survey about the most recent 3D handheld scanners is presented. As second, a study about the possibility to employ the handheld scanners in the field of Cultural Heritage is conducted. In this investigation, a doorway of the Benedictine Monastery of Catania, has been used as study case for a comparison between stationary Time of Flight scanner, photogrammetry-based 3D reconstruction and handheld scanning. The study is completed by an evaluation of the meshes quality obtained with the three different kinds of technology and a 3D modeling reproduction of the case-study doorway

HANDHELD VOLUMETRIC SCANNER for 3D PRINTED INTEGRATIONS of HISTORICAL ELEMENTS: COMPARISON and RESULTS

The latest technologies in the field of geomatics and additive manufacturing can provide a significant support to the restoration and conservation activities of Cultural Heritage (CH). In particular, the recent developments for both the 3D scanning techniques and the 3D printing systems are able to speed up the survey and the reconstruction of historical fragments gone lost. This research compares different meshes, obtained with different instruments and techniques, in particular a medium and a short- range volumetric handheld camera, with the aim of evaluating the best solution for the 3D printing and provide some guidelines for this kind of operation. Therefore, the focus is mainly on identifying the most effective solution to describe, represent and subsequently model small architectural details in the most automatic way, in order to step from the survey to the final printed result in the shortest time possible. Moreover, an attempt to integrate and complete not only sculptural details, by now well stated in the state of art, but also architectural elements, respecting the principles of reversibility and material recognisability typical of the modern restoration theories, has been done. The case study examined is an historical wooden gilded door with the lack of some decorative parts, in a church in the centre of Turin (Italy), symbol of the baroque architecture and damaged by a fire occurred during the Second World War

3D MODELS FOR ALL: LOW-COST ACQUISITION THROUGH MOBILE DEVICES IN COMPARISON WITH IMAGE BASED TECHNIQUES. POTENTIALITIES AND WEAKNESSES IN CULTURAL HERITAGE DOMAIN

Nowadays, 3D digital imaging proposes effective solutions for preserving the expression of human creativity across the centuries, as well as is a great tool to guarantee global dissemination of knowledge and wide access to these invaluable resources of the past. Nevertheless, in several cases, a massive digitalisation of cultural heritage items (from the archaeological site up to the monument and museum collections) could be unworkable due to the still high costs in terms of equipment and human resources: 3D acquisition technologies and the need of skilled team within cultural institutions. Therefore, it is necessary to explore new possibilities offered by growing technologies: the lower costs of these technologies as well as their attractive visual quality constitute a challenge for researchers. Besides these possibilities, it is also important to consider how information is spread through graphic representation of knowledge. The focus of this study is to explore the potentialities and weaknesses of a newly released low cost device in the cultural heritage domain, trying to understand its effective usability in museum collections. The aim of the research is to test their usability, critically analysing the final outcomes of this entry level technology in relation to the other better assessed low cost technologies for 3D scanning, such as Structure from Motion (SfM) techniques (also produced by the same device) combined with dataset generated by a professional digital camera. The final outcomes were compared in terms of quality definition, time processing and file size. The specimens of the collections of the Civic Museum Castello Ursino in Catania have been chosen as the site of experimentation

SURVEY OF HISTORICAL GARDENS: MULTI-CAMERA PHOTOGRAMMETRY VS MOBILE LASER SCANNING

This paper presents an investigation into the characterization of historical gardens by comparing two 3D survey methodologies. In this context, approaches employing terrestrial laser scanning are considered the most accurate, while Mobile Mapping Systems (MMSs) are considered promising due to their extreme productivity. Less common is the use of close-range photogrammetry. This paper compares two approaches based on the use of a wearable MMS and the use of an in-house built photogrammetric multi-camera prototype. The comparison aims to assess the applicability of the two techniques in this field, evaluating their advantages and disadvantages in surveying a historical garden and extracting information for tree inventory, such as the DBH (Diameter at Breast Height) and canopy footprint. We compared the practicality of surveying and processing operations; and the quality and characteristics of the point clouds obtained. Both systems produced a dense representation of the terrain. The multi-camera survey resulted to be more defined due to the lower noise of the point cloud but incomplete in the definition of tree canopies. DBH of tree trunks can be extracted with both systems, except for thinner and finer diameter trunks detected by the MMS approach but not always by the multi-camera. The MMS approach proved more effective thanks to a shorter survey time required to cover an equal area and the fact that the MMS survey alone is sufficient for the geometric description of trees. In contrast, the multi-camera approach cannot avoid integration with an aerial survey for canopy reconstruction

SURVEY OF HISTORICAL GARDENS: MULTI-CAMERA PHOTOGRAMMETRY VS MOBILE LASER SCANNING

This paper presents an investigation into the characterization of historical gardens by comparing two 3D survey methodologies. In this context, approaches employing terrestrial laser scanning are considered the most accurate, while Mobile Mapping Systems (MMSs) are considered promising due to their extreme productivity. Less common is the use of close-range photogrammetry. This paper compares two approaches based on the use of a wearable MMS and the use of an in-house built photogrammetric multi-camera prototype. The comparison aims to assess the applicability of the two techniques in this field, evaluating their advantages and disadvantages in surveying a historical garden and extracting information for tree inventory, such as the DBH (Diameter at Breast Height) and canopy footprint. We compared the practicality of surveying and processing operations; and the quality and characteristics of the point clouds obtained. Both systems produced a dense representation of the terrain. The multi-camera survey resulted to be more defined due to the lower noise of the point cloud but incomplete in the definition of tree canopies. DBH of tree trunks can be extracted with both systems, except for thinner and finer diameter trunks detected by the MMS approach but not always by the multi-camera. The MMS approach proved more effective thanks to a shorter survey time required to cover an equal area and the fact that the MMS survey alone is sufficient for the geometric description of trees. In contrast, the multi-camera approach cannot avoid integration with an aerial survey for canopy reconstructio

MOBILE MAPPING FOR CULTURAL HERITAGE: THE SURVEY OF THE COMPLEX OF ST. JOHN OF THE HERMITS IN PALERMO (ITALY)

During the 11th and 12th century, the Arab-Norman architectural style characterized the most beautiful and important Cultural Heritage buildings in Sicily, and especially in Palermo (Italy). The relevance of these monuments is highlighted by their inclusion in the UNESCO World Heritage Sites List in 2015. For many years, the University of Palermo has been studying and documenting several Arab-Norman cultural assets, and in particular, the complex of St. John of the Hermits in Palermo (Italy). A first detailed 3D survey of the main structures of this complex was carried out using a terrestrial laser scanner while the 3D survey of the entire complex was made using a Mobile Mapping System (MMS). The paper describes the workflow and the results of the mobile mapping survey undertaken with a Handheld Mobile Laser Scanner (HMLS) based on Simultaneous Localisation and Mapping (SLAM) technologies. The work allowed surveying the entire site with an extremely fast acquisition and obtaining the geometric information useful for historical architectural valuations. In addition, due to the characteristics of the site, the work enabled the assessment of the HMLS data processing testing different automatic algorithms for point cloud filtering

Point clouds by SLAM-based mobile mapping systems: accuracy and geometric content validation in multisensor survey and stand-alone acquisition

The paper provides some operative replies to evaluate the effectiveness and the critical issues of the simultaneous localisation and mapping (SLAM)-based mobile mapping system (MMS) called ZEB by GeoSLAM™ https://geoslam.com/technology/. In these last years, this type of handheld 3D mapping technology has increasingly developed the framework of portable solutions for close-range mapping systems that have mainly been devoted to mapping the indoor building spaces of enclosed or underground environments, such as forestry applications and tunnels or mines. The research introduces a set of test datasets related to the documentation of landscape contexts or the 3D modelling of architectural complexes. These datasets are used to validate the accuracy and informative content richness about ZEB point clouds in stand-alone solutions and in cases of combined applications of this technology with multisensor survey approaches. In detail, the proposed validation method follows the fulfilment of the endorsed approach by use of root mean square error (RMSE) evaluation and deviation analysis assessment of point clouds between SLAM-based data and 3D point cloud surfaces computed by more precise measurement methods to evaluate the accuracy of the proposed approach. Furthermore, this study specifies the suitable scale for possible handlings about these peculiar point clouds and uses the profile extraction method in addition to feature analyses such as corner and plane deviation analysis of architectural elements. Finally, because of the experiences reported in the literature and performed in this work, a possible reversal is suggested. If in the 2000s, most studies focused on intelligently reducing the light detection and ranging (LiDAR) point clouds where they presented redundant and not useful information, contrariwise, in this sense, the use of MMS methods is proposed to be firstly considered and then to increase the information only wherever needed with more accurate high-scale methods

LASER-VISUAL-INERTIAL ODOMETRY BASED SOLUTION FOR 3D HERITAGE MODELING: THE SANCTUARY OF THE BLESSED VIRGIN OF TROMPONE

Abstract. The advent of new mobile mapping systems that integrate different sensors has made it easier to acquire multiple 3D information with high speed. Today, technological development has allowed the creation of portable systems particularly suitable for indoor surveys, which mainly integrating LiDAR devices, chambers and inertial platforms, make it possible to create in a fast and easy way, full 3D model of the environment. However, the performance of these instruments differs depending on the acquisition context (indoor and outdoor), the characteristics of the scene (for example lighting, the presence of objects and people, reflecting surfaces, textures) and, above all, the mapping and localization algorithms implemented in devices. The purpose of this study is to analyse the results, and their accuracy, deriving from a survey conducted with the KAARTA Stencil 2 handheld system. This instrument, composed of a 3D LiDAR Velodyne VLP-16, a MEMS inertial platform and a feature tracker camera, it is able to realize the temporal 3D map of the environment. Specifically, the acquisition tests were carried out in a context of metrical documentation of an architectural heritage, in order extract architectural detail for the future reconstruction of virtual and augmented reality environments and for Historical Building Information Modeling purposes. The achieved results were analysed and the discrepancies from some reference LiDAR data are computed for a final evaluation. The system was tested in the church and cloister of the Sanctuary of the Beata Vergine del Trompone in Moncrivello (VC) (Italy).</p