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

Optimization of survey procedures and application of integrated digital tools for seismic risk mitigation of cultural heritage: The Emilia-Romagna damaged theatres.

Starting from current procedures, standards and tools for seismic damage survey, the research presents an integrated workflow for seismic damage documentation and survey applied to historic theatres in the Emilia-Romagna region damaged by the 2012 earthquake. The 2012 earthquake highlighted the fragility of the cultural heritage and underscored the lack of proactive conservation and management of historic assets. The research starts by analysing Agenzia Regionale per la Ricostruzione della Regione Emilia-Romagna- ARRER’s requests, which had found criticalities in applying the current Mic (Ministero della Cultura) procedures for the damage survey of complex types: the A-DC form for churches and the B-DP form for buildings. Using the two types of forms highlighted the lack of ad hoc tools for complex architectural styles such as castles, cemeteries and theatres, resulting in the loss of quantitative and qualitative information necessary for knowledge, conservation and thus management of the reconstruction process. As a result of these considerations, national and international standards of integrated documentation, existing digital databases for cataloguing and classification of cultural property, and seismic risk management were studied to develop a workflow of integrated procedures for seismic damage survey on the specific assigned case study: Regional Historic Theaters affected by the 2012 earthquake. The research used the holistic and interdisciplinary approach of integrated documentation to develop the integrated procedural workflow to enhance and optimise seismic damage detection operations in the case study. In providing a workflow of integrated procedures for the prevention and mitigation of hazards related to potential states of emergency, both natural and anthropic, the research follows an “extensive” methodological approach to test the survey outside the Emilia crater. The methodological framework led to the critical-comparative analysis, divided into two levels: the first involved studying critical issues in the B-DP form, mainly used in the 2012 theatre survey. The second level covered the techniques - laser scanning, digital photogrammetry - and integrated survey methodologies applied during the in-depth investigations for repair and restoration work. The critical-comparative analysis and morpho-typological study led to the development of an integrated procedural flow to survey damage in historic theatres. It is aimed at systematising and optimising the stages of damage documentation. The workflow consists of three information levels: L1. Screening level for the visual survey; L2 survey level defines the 3D acquisition steps for the geometric-dimensional study by theatres. The BIM L3 Plus level guides implementing the level of knowledge of parametric HBIM models for documentation, management and monitoring of historic theatres

BIM model for existing building stock: optimisation and validation of the processes

This research was developed within an Industrial Doctorate project involving two sponsors: the Negroni Key Engineering company with a consolidated background in the computer sector, more specifically in BIM, and Platinum partner of Autodesk; and the Universidad de Valladolid which for years has been performing critical studies in the field of photogrammetric and laser scanner surveying and digitalisation. The study presented here continues along these lines in order to define a work method for the digitalisation and management of existing building heritage. It must be resilient, envisage sustainable procedures for both the public administration and private entities, and identify the potential of the current systems as well as any critical issues. The work method is based on six work phases, each one preliminary to the next; they are: • Model Definition, indicating the geometric and information characteristics of the BIM models; • Data Acquisition, in which details are provided regarding the data to be acquired and relative survey method; • Model Reconstruction, during which different instruments of the BIM platforms are used to complete the digital twin of the building; • Model Checking, including the operations needed to ensure that all the elements are coherent, both graphically and from the point of view of information; • Model Fixing, envisaging integration, where necessary, of further studies so as to ensure correct completion of the study; • Data Management, characterised by the importation of the result obtained in a GIS platform, cataloguing, and reuse of the result. The optimisation strategies identified are: • The definition of a BIM GIS methodology and the consequent drafting of guidelines, describing the step-by-step progress of the processes contained in each phase of work; • The writing algorithms for the recognition of geometric elements in BIM software; • The creation of parameters that define the reliability of the input data necessary for the reconstruction of the building model. The innovative features of the research are: • The multiscalar management of the building stock, through the combined use of GIS and BIM platforms; • The complete discipline of the digital process extends from acquisition to data management; • The integration of semi-automatic CADToBIM and ScanToBIM processes, through new applications specially developed to optimise the reconstruction of specific objects; • the definition of the parameters CoIN (Confidence of Information Needed), relating to the reliability of the data needed to reconstruct the model, and SuRe (Survey Required), relating to the integration of surveys to be performed in order to complete the process. The doctoral thesis is divided into five parts: • definition of the state of the art, presenting the fundamental features of the issues in questions; • description of the work method, including the strategies to optimise the processes; • identification of the research field and case studies in order to validate the aforementioned methodology; • results and conclusions; • annexes

Digital Twinning for 20th Century Concrete Heritage: HBIM Cognitive Model for Torino Esposizioni Halls

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

HIGH-RESOLUTION DIGITAL SURVEY OF FLOORS: A NEW PROTOTYPE FOR EFFICIENT PHOTOGRAMMETRIC ACQUISITION

High-resolution surveying of historical floors is a very common practice in both research and everyday life. The type of floors typically concerned are made of mosaic, marble and stone. Because of their intrinsic characteristics, their survey typically requires very highresolution results, to ensure excellent support for restoration, as well as in-depth knowledge of the artifact. In these cases, the focus must be kept on both geometric and radiometric content, to enable accurate metric representation and a rendering of colour and surfaces as close as possible to reality. In this research we propose a prototype of a photogrammetric acquisition system (under development) which tries to optimise the floor survey in terms of both geometric and colour documentation. In particular, the prototype makes use of the cross-polarisation technique with the aim of eliminating reflections from the images. The principle behind the prototype is the creation of a movable laboratory, a segregated space that allows excellent photographic acquisition even in difficult environmental conditions, which cannot always be controlled optimally. First tests showed its suitability and usefulness to reach the goal of a high resolution survey of historic floors

Development of a platform recommending 3D and spectral digitisation strategies

[EN] Spatial and spectral recording of cultural heritage objects is a complex task including data acquisition, processing and analysis involving different technical disciplines. Additionally, the development of a suitable digitisation strategy satisfying the expectations of the humanities experts needs an interdisciplinary dialogue often suffering from misunderstanding and knowledge gaps on both the technical and humanities sides.Through a concerted discussion experts from the cultural heritage and technical domains currently develop a so-called COSCHKR platform (Colour and Space in Cultural Heritage Knowledge Representation) which will give recommendations for spatial and spectral recording strategies adapted to the needs of the cultural heritage application. The platform will make use of an ontology through which the relevant parameters of the different domains involved in the recording, processing, analysis and dissemination of cultural heritage objects are hierarchically structured and are related through rule-based dependencies. Background and basis for this ontology is the fact that a deterministic relation exists between (1) the requirements of a cultural heritage application on spatial, spectral, as well as visual digital information of a cultural heritage object which itself has concrete physical characteristics and (2) the technical possibilities of the spectral and spatial recording devices. Through a case study which deals with the deformation analysis of wooden samples of cultural heritage artefacts this deterministic relationship is illustrated explaining the overall structure and development of the ontology.The aim of the COSCHKR platform is to support cultural heritage experts finding the best suitable recording strategy for their often unique physical cultural heritage object and research question. The platform will support them and will make them aware of the relevant parameters and limitations of the recording strategy with respect to the characteristics of the cultural heritage object, external influences, application, recording devices, and data.This work was partly supported by COST under Action TD1201: Colour and Space in Cultural Heritage (COSCH).Wefers, S.; Karmacharya, A.; Boochs, F. (2016). Development of a platform recommending 3D and spectral digitisation strategies. Virtual Archaeology Review. 7(15):18-27. doi:10.4995/var.2016.5861.SWORD182771

From Point Cloud To Video Projection Mapping: Knowing Modern Architecture By Using Light Projection

The ClusterLab HeModern of the Università Iuav di Venezia has been working in recent years on the study, knowledge and conservation of 20th century architecture. This interdisciplinary research group (History of Architecture, Geomatics, Building Technology, Restoration Project) intends to investigate how to analyse and evaluate the state of conservation of the materials of which the modern architectural cultural heritage is composed by identifying specific application protocols for intervention, preservation and valorisation. In 2018, the collaboration between the above-mentioned ClusterLab, the LéaV of the Ecole nationale supérieure d'architecture in Versailles and the Archivio del Moderno of the Accademia di architettura in Mendrisio - Università della Svizzera italiana, culminated in the identification of the works and career of André Bloc as a case study. In the context of this study, the Tour, the Engineer's posthumous work, was selected to serve as a sample for research on the methods of communication of the contents of the architecture, the survey procedures used and the elaborations obtained. So, after the survey campaign, which took place via topographic, laser scanning and photogrammetric methods, two different levels of restitution were conceived: the first, made according to the canonical graphic paper methods, represents the procedural and surveying information, the material characterisation and the state of decay; the second elevates the same contents by applying them to physical reality. In this phase, the research focused on the possibility of making the different projects collaborate through the technique of rapid prototyping and video projection mapping. This particular form of augmented reality was used to enrich, through the mediation of light projections, the sensory perception of the observers by adding more information and emphasising those of greatest interest, proposing an alternative way of storytelling. In fact, unlike other forms of augmented reality, in the case of video projection mapping, the observer has the possibility to interact continuously with the physical reality, whose character is static, while the transmission of data is dynamic and can range in heterogeneity. The elaborations produced were presented in form of a museum exhibit at the international conference "Arti e architettura. Il contributo di André Bloc 1950-1970", which took place in the exhibition rooms of the Università Iuav di Venezia