Management of Built Heritage Via The HBIM Project: A Case Study Of Flooring And Wall Tiling

Virtual Archaeology Review, 7(14): 1-12, 2016 http://dx.doi.org/10.4995/var.2016.4349 © UPV, SEAV, 2015 Received: November 18, 2015 Accepted: May 5, 2016 * Corresponding Author: Juan Enrique Nieto, [email protected] DOI: http://dx.doi.org/10.4995/var.2016.4349 1 MANAGEMENT OF BUILT HERITAGE VIA THE HBIM PROJECT: A CASE STUDY OF FLOORING AND WALL TILING LA GESTIÓN DEL PATRIMONIO CONSTRUIDO A TRAVÉS DEL PROYECTO HBIM: UN ESTUDIO DE CASO DE PAVIMENTOS Y ALICATADOS Juan Enrique Nieto*, Juan José Moyano, Fernando Rico and Daniel Antón Departamento de Expresión Gráfica e Ingeniería en Edificación, Escuela Técnica Superior de Ingeniería de Edificación, Universidad de Sevilla, Avenida Reina Mercedes, 4A, 41012, Sevilla, España. [email protected]; j[email protected]; [email protected]; [email protected] Abstract: Building Information Modelling (BIM) is a collaborative system that has been fully developed in the design and management of industries involved in Architecture, Engineering and Construction (AEC) sectors. There are, however, very few studies aimed at managing information models in the field of architectural and cultural heritage interventions. This research therefore proposes an innovative methodology of analysis and treatment of the information based on a representative 3D graphic model of the flooring and wall tiling of a historic building. The objective is to set up a model of graphic information which guarantees the interoperability of the aforementioned information amongst the diverse disciplines intervening in the conservation and restoration process. The Pavillion of Charles V, a Renaissancecharacterised building located in outdoor areas of the Alcazar of Seville, Spain, was selected for the study. This work constitutes a project of intervention based on Heritage or Historic Building Information Modelling, called the “HBIM Project”. Key words: HBIM Project, Historic Building Information Modelling, patrimonial information model, photogrammetric restitution, Architectural Archaeology, BIM. Resumen: El Modelado de Información para la Construcción (BIM) es un sistema colaborativo que actualmente está plenamente desarrollado en el diseño y la gestión de las industrias involucradas en el sector de la Arquitectura, Ingeniería y Construcción (Architecture, Engineering and ContructionAEC). En cambio, en el ámbito de las intervenciones en el Patrimonio Cultural y Arquitectónico, son muy pocos los estudios dedicados a gestionar modelos de información. Por ello, esta investigación propone una metodología innovadora de análisis y tratamiento de la información basada en un Modelo gráfico 3D representativo de pavimentos y alicatados de un Edificio Histórico. La finalidad es crear un modelo de información gráfica que garantice la interoperabilidad de dicha información entre las diversas disciplinas que intervienen en el Proceso de Conservación y Rehabilitación Patrimonial. Para el estudio, se ha seleccionado el Cenador de Carlos V (o de la Alcoba); edificio de carácter renacentista perteneciente a los espacios exteriores del Alcázar de Sevilla, España. Este trabajo constituye un proyecto de intervención basado en un modelo de información patrimonial o del edificio histórico, denominado “Proyecto HBIM”. Palabras clave: Proyecto HBIM, Historic Building Information Modelling, modelo de información patrimonial, restitución fotogramétrica, Arquelogía de la Arquitectura, BIM. 1. Introduction Digital information systems are now the primary tools for scientific research in the field of cultural and architectural heritage management. Meyer et al. (2007) proposed a virtual environment implemented by Geographic Information Systems (GIS) for researching in the field of cultural and architectural heritage. In addition, there has been an advance based on the division of a building into parts in the form of box systems conducted via GIS in order to document, catalogue and manage the restoration process. The latest enquiries in systems which are applied to architectural heritage models range from a two-dimensional (2D) GIS system to a 3D-content model for built heritage preservation and management. This is possible thanks to the simplified parametric models that are suitable for industrial elements and those models from modern architecture. Terms reinforcing the concept of Historic Building Information Modelling (hereinafter HBIM) involve the establishment of preventive conservation as a real quotidian need, the exchange of information and the dissemination of knowledge of architectural heritage (Oreni 2013). NIETO et al., 2016 2 Virtual Archaeology Review, 7(14): 1-12, 2016 Other lines of research on the subject support City GML as a standard methodology for 3D information storage that is related to architectural heritage (Prieto et al. 2012). City GML is an implementation scheme for spatial data exchange. Its objective is to define basic entities through: attributes; 3D model relations; and design principles based on geometric properties and semantics. Although this model does not meet architectural heritage documentary needs, it can be extended with “Core Data Standard for Archaeological Sites and Monuments”. For the research discussed in this paper, 3D modelling — informed by laser scanning and photogrammetry — is used to develop an efficient and accurate representation of diverse and complex architectonic structures. The potential to use these models to simulate and visualize possible future or past conditions is made possible by Building Information Modelling (hereinafter BIM). The essence of BIM is to achieve a database of graphic and alphanumeric information where each participative discipline integrates its knowledge in parametric software and adapts to building features in a coordinated manner. Thus, BIM becomes a strategy of collaboration that implies the exchange of contents and transparency between all the actors, thereby creating a teamworkbased culture (Garagnani 2012). Recent research into this approach supports the application of this technology to newly constructed buildings, where owners, builders and installers participate in the functionality of BIM. However, an increasing number of maintenance interfaces and functionalities are now being applied to extant buildings (Volk et al. 2014). There are studies in the field of information modelling research that enable virtual reconstruction, through metric plans and documentary evidence, to raise awareness concerning demolished public buildings that belong to lost heritage (Boeykens et al. 2012). The recognition of BIM as a technology is due to the multi-disciplinary knowledge base where life-cycle processes, for example operation, renewal and development of the growing inventory of heritage sites are managed (Fai et al. 2011). Nevertheless, this technology as a centre for data records for architectural heritage documentation has yet to be fully explored (Fai et al. 2013). In this respect, it is to be considered that disciplines such as archaeology, which produces information records as a whole, are expanding since studies into objects are becoming more in depth, and thereby causing systems to be more complex. One of the main challenges to implementing BIM in the AEC sector has been interoperability with existing information management systems both within individual disciplines and between disciplines. This continues to be an area of active research (Demian and Walters 2013; Grilo and Jardim-Goncalves 2010). It is significant in this context that communication between the diverse professionals involved in architectural heritage is often time even more complex than in the construction industry. Each discipline in the restoration and rehabilitation of historic buildings presents its own peculiarities. Architects, archaeologists, art historians, restorers, and photographers constitute the artistic labour involved in the procedurers of intervention. Participation in this kind of multidisciplinary work requires the establishment of shared hypotheses, data exchange and analyses of results. Nevertheless, major problems arise in the compartmentalisation and duplication of information. It is now widely accepted in the field of architectural heritage that an international standard for information management needs to be established. The case study presented in this paper is developed within the framework of the precedents discussed above, where a 3D model with data records is created in the audit stage. The audit stage can be defined as the amount of operations carried out to ascertain the nature of a historic building. It also introduces a working hypothesis about the mosaics and tiling areas. This study has been implemented using well estabished methodologies for stratigraphic analysis as the basis of archaeology and architecture. Following González (2003), the main phases of restoration of monuments — reading, reflection and intervention — the project should be interpreted as the ultimate expression of hypotheses that only subsequent verification will ratify. A project of intervention — the so-called HBIM Project, which includes an information model for heritage — admits the application of inverse engineering by using parametric objects in order to constitute construction parts. These are created by means of laser scanning and photogrammetric techniques (Dore and Murphy 2014), thereby making it possible to achieve current state diagnosis. Therefore, the starting point should be a BIM supported by the aforementioned precise modelling techniques (Murphy et al. 2009) for the purpose of becoming the core of an intervention project in architectural heritage. This will assist the professionals involved in defining the chronotypological sequence with the characterisation and individualisation of variables in the analysis of facings (Azkarate 2002). 2. Method and construction process of the HBIM Project for flooring and tiling This project organises information in the HBIM by defining construction elements, filtering data and visualising wall structures. The subject for our case study is the Pavillion of Charles V (Fig. 1). Built in the mid-sixteenth century following the design of Juan Hernandez, it is a quintessential Spanish Renaissance building. Located in the Jardin de la Cruz of the Alcazar of Seville, it is considered an architectural monument of great heritage value and has been listed as a UNESCO Heritage Site since 1987. The Pavillion currently presents buiding pathologies that are the result of deferred maintenance. Planning the HBIM Project involves the organisation of information through a protocol created simultaneously with the construction of the BIM and both the historical and the physical-constructional analysis of the Pavillion. MANAGEMENT OF BUILT HERITAGE VIA THE HBIM PROJECT: A CASE STUDY OF FLOORING AND WALL TILING Virtual Archaeology Review, 7(14): 1-12, 2016 3 Figure 1: South-west perspective of the Pavilion in the HBIM Project. In this first stage, information related to geometry, polychromies, construction methods, and deferred maintenance are gathered together along with those elements that are the focus of our study — flooring and tiling. As a second step, all elements are organised into categories and inserted into the model. ArchiCAD offers an array of functions to define building elements and provides a substantial library of parametric objects and materials. This BIM software works with a series of layers related to a construction category, but it is necessary to establish new layers depending on the historic building analyses so that elements identified in an intervention can be assembled in the modelling process. These layers serve as simple containers of elements grouped by characteristics including dimensions, materials and function in the building. However, it is occasionally necessary to sort these elements within the group by their spatial location or detected particularities. In this way, the classification into categories (typology, structural function, position, and rehabilitation status) of every element displayed in the model contributes to the HBIM. Subsequent to this process, the identification of each parametric object is carried out. A characteristic identifier (ID) related to the classified construction parts is applied. The purpose of ths identifier is to identify and cluster the elements specific to each disciplines involved in the restoration process and to facilitate the represention in these elements in discipline specific drawings. A filtering process is required to display information from the model in stages depicting the temporal and constructional evolution of the building. This process is conducted using specific tools from ArchiCAD software that support graphic data exchange between the diverse professionals that comprise the multidisciplinary work team. The flow chart in Figure 2 outlines the process for developing an advanced HBIM. This involves two distinct phases. First, a survey for gathering 3D data using laser scanning and photogrammetry (Murphy et al. 2009). Second, the development of a building information model for the management of architectural heritage. The main proposal of this research sets three action levels: the aforementioned survey in order to adjust the images to the model by means of photogrammetric rectification; the identification and cataloguing of irregular pieces; and finally the management of information. Figure 2: Proposal of the HBIM Project. Modelling with parametric elements in the 2.1. HBIM Project Currently, BIM software includes design tools to model elements from construction systems, such us slabs, pillars, joists and roofs. These elements are developed as parametric objects of architectonic pieces, standardised profiles and parts from already patented technological systems. BIM developed for use in the Architecture, Engineering and Construction (AEC) industry are optimized for new buildings. While the modelling procedure is the same in the case of an historic building, significant challenges arise when the model is built with construction elements defined according to historical data. In these cases, it is necessary to adapt the software to use traditional construction techniques and materials. This involves the exploration historical-constructional stages, where Geometric Descriptive Language (GDL) libraries are used to create a primitive model by following an ideal geometry. Parameters are subsequently modified as the exploration of pathologies progresses. Recent studies highlight the capacity to create a historical framework that contains an extensive parametric library of architectonic features based on manuscripts of architecture (Murphy et al. 2013). This work represents an advance in the generation of architectural intervention models, where GDL objects facilitate accurate parametric modelling of traditional materials and methods of construction within a BIM environment. NIETO et al., 2016 4 Virtual Archaeology Review, 7(14): 1-12, 2016 2.1.1. Ortho-rectification for surface mapping The use of ortho-rectified photography as an effective tool for the documentation of cultural heritage is studied well established in current scientific literature (e.g. McCarthy 2014). For the HBIM Project, information is structured in accordance with the logical restoration process in order to facilitate the restitution procedure and to prevent errors. To this end, a new, fixed and considerably long focal length — greater than the depth of the Pavillion’s loggias — was needed. It was decided to photograph consecutively around the perimeter of the building and to avoid the columns. Photographs were taken perpendicularly to the tiling using a single lens reflex (SLR) digital camera Canon EOS 500D with an 18-55 mm lens, exposure value f/3.5-5.6 and 18 mm focal length. Figure 3: Sectorisation of tiling areas in the northern façade of the Pavilion. Borders and changes in decorations are delimited later by specifying their coordinates to facilitate the characterisation of the walls. Data transfer is then carried out by fragmenting the surface of the wall in the model, classifying it in functional sectors and identifying each of the pieces of tessellation (Figs. 3 and 4). These pieces are shown and identified with labels in each dimensioned sector of the elevation by utilising the <Morph> tool in ArchiCAD. 2.1.2. Mapping and fragmenting of the HBIM Project In order to map the tiled surfaces of the Paviillion, orthoimages are associated with the ‘wall finish’ layer of the model. A unique texture is created for each sector of tiled wall — or decorative element — over the surface and is included in the surface library of the ArchiCAD software. This method allows for a photo-realistic mapping of the tiles and friezes. This allows elements to be explored more easily on the surface of the wall: ashlar and brick bonding, tiling, friezes and decorative details. This facilitates the analysis of peculiarities and historical characteristics of materials and allows for a typological identification of each piece before undertaking their reinstatement. The borders of individual tiles are delineated utilising the <Pencil> tool from the Editing Palette. The ortho-image associated with the facing <Morph> of the walls is used as a template. Once the vector grid of those pieces is concluded, tiles are selected in terms of their typology to obtain new isolated shapes (tile and frieze) from the area, which is then fragmented (Fig. 5). Figure 4: Visualisation of the model in the HBIM Project. MANAGEMENT OF BUILT HERITAGE VIA THE HBIM PROJECT: A CASE STUDY OF FLOORING AND WALL TILING Virtual Archaeology Review, 7(14): 1-12, 2016 5 Figure 5: Sub-elements with the same typology are converted into isolated elements. This methodology enables the geometry of the wall to be accurately recorded. However, it should be taken into account that ceramic tiles from the 16th century are often damaged. In the specific case of the Pavillion, audited pathologies show a noticeable irregular alignment, with signs of continuous repairs. As a result, tracing each individual tile (using the <Wall> tool in ArchiCAD) would have been a tiresome and imprecise task. Instead, we used a specific API in ArchiCAD to expedite the tracing and automatically create a normalized vector grid (with its original ID: Az-NI_Cen). After this task, the identification process and piece labelling with identifiers was performed. In the case of the centre-left facing in the northern façade, this was accomplished by using the names of animals and mythological characters that had been depicted: horse, centaur, wolf, monkey, satyr and unicorn. It is important to note that the pieces (as isolated elements) maintain the image of the corresponding tile within the matrix (Fig. 6). Figure 6: Identification of pieces in the central left-hand sector of the facing in the northern façade. NIETO et al., 2016 6 Virtual Archaeology Review, 7(14): 1-12, 2016 2.1.3. Identification of pieces for floor restoration The extraordinary composition of mosaics and clay tiles, both delimited by ceramic borders and inserts forming equidistant squares and radial shapes, presented pathologies caused by the presence of lime in the water and the abrasion linked to the cladding. The pieces are identified according to their geometric shape: circle, heart, star, flower, octagon, oval, pentagon, rhombus, oval rhombus and triangle. The procedure of delimiting and identifying pieces is similar to that used in wall tiling. The first step involved the conversion of the element <Slab> (the floor of the room) into tool <Morph> in order to connect it to the ortho-image from the floor (Fig.7). Figure 7: Top view of the floor mapped with multiple orthorectificated shots. The Pavillion of Charles V. Here, following the same work method, the boundaries of floor tiles, friezes and central sectors containing inserts (ceramic rhombic and rectangular pieces) are delineated using the <Pencil> tool from the Editing Palette within the <Morph> tool, but without dividing the floor into parts (Fig. 8). Once this has been performed, the vector grid is superimposed onto the image of the floor, which is comprised of various closed geometric shapes. Only a single ensemble is hitherto constituted; here, however, the division of the matrix into <Morph> subelements is carried out in order to identify pieces by individual typologies. Floor tiles, perimeter friezes, rhombus mosaics and the vertex pieces in the central area are all differentiated. Finally, clay tiles are isolated from the rest of the floor and contain their respective ortho-image adjusted without undertaking other operations (Fig. 9). Figure 8: Demarcation of floor tiles and friezes in the room of the Pavillion. Figure 9: Floor sectorised into typologies depending on its filtering: Shape type, Floor Tiles layer, ID of the element. MANAGEMENT OF BUILT HERITAGE VIA THE HBIM PROJECT: A CASE STUDY OF FLOORING AND WALL TILING Virtual Archaeology Review, 7(14): 1-12, 2016 7 Figure 10: a. Session model with flooring once outlined. b. Floor sectorised by typologies: Shape, Floor Tiles layer, element’s ID. The ensuing step is to classify each floor tile with its own ID and a label in terms of the motif it displays. For instance, FT-Oval ID is used for the piece Oval. When the tiles are sorted according to their kind, they can be added the new layer created (Fig. 10). 2.1.4. Labelling of pieces in restoration works The 2D plan and elevation projections are produced once all of the pieces from the floor tiles, friezes and the rest of the decorative fragments from the floor have been identified. Labels function as text blocks or optional symbols linked to construction parts and 2D patterns. In general, the ID is shown in the label as the basic identification of all elements of the HBIM Project, but there are cases in which information in plans must be improved by adding more data to ease the labour of researchers in restoration. Various types of labels are utilised in the case of the Pavillion of Charles V. For instance, Az-ND_Cen indicates the tiling of the northern facing, centrally located in the right-hand sector. Each piece of tile is individually labelled in this process. The first label specifies the position of the piece with respect to a relative reference point (eg. lower left) in order to compose an array of coordinates prior to dismantling the tiles for off-site restoration. Additional information on each piece appears in what we have termed the “second label”. This includes typology, motif and preservation status. It also shows identification for its classification. For example, A001Nci for the ridged tile with the motif Goat, located in the upper left-hand side of the central sector of the northern facade (Fig. 11). This advanced label is called the Label Multileader (http://www.masterscript.nl/), and is associated with each tile and possesses two signatures, one for categorisation and another for information from the audit. (a) (b) Figure 11: Partial elevation of the tiling sector Az-NI_Cen: a) Texture; b) Labels for identification. 2.1.5. Association of materials and construction systems In order to identify a specific element within a larger area under study, a construction material from the ArchiCAD database is linked to the piece. The software permits access to a catalogue of physical properties such as thermal conductivity, density and heat capacity. It is then subdivided into construction typologies selected from standard or custom options. Data related to materiality, geometry, assembly, and other physical properties is integrated in the BIM. This data can be consulted by all professionals working on the project. Diverse elements (tiles, friezes and mosaics) are present in the facing in this study. In order to identify geometric alterations in all pieces of the same material, physical properties, and identical production system, the structure NIETO et al., 2016 8 Virtual Archaeology Review, 7(14): 1-12, 2016 and external appearance were linked to a vector grid which is associated with the shape and the distinctive texture of each typology of pieces. Figure 12 shows the edition of a construction material of a Ridged Vitrified Tile. Figure 12: Edition of the Ridged Vitrified Tile. 2.1.6. Data management and lists of elements Once the graphic procedures of sectorisation, classification and identification of tiling and flooring have been achieved, the databases can be composed. A basic criterion that defines the information is established so that data can be filtered and viewed. The sorting of elements by their interior or exterior position within the model (Fig. 13) and by their rehabilitation status among other standards is necessary for their classification by families in the model. The inserted pieces are identified in tiling and flooring and then a register of stratigraphic units is created (already identified in the archaeological study). It is also possible to list present pathologies and deformations in certain elements of the Pavilion. Finally, charts obtained for the inventory and exploration of elements of this HBIM Project display rows where pieces are identified by types. All varieties of tiles and friezes are inventoried in the northern exterior facing of the building (Fig. 14). In the case of the floor, the inventory sheet holds information on 183 floor tiles, making a total area of 26.57 m2. The grid composed of perimeter friezes as a group and is identified as the Pav-Frieze unit, makes 8.90 m2. Other data of interest for the completion of the sheet by the restoration specialist appears in the rest of the columns, and includes chronology, dating, conservation status and atmospheric, biological, mechanical and chemical aggression (Figs. 15 and 16). Figure 13: Section of the model of the Pavillion of Charles V in the HBIM project. MANAGEMENT OF BUILT HERITAGE VIA THE HBIM PROJECT: A CASE STUDY OF FLOORING AND WALL TILING Virtual Archaeology Review, 7(14): 1-12, 2016 9 Figure 14: Visualisation of the Inventory Sheet of Tiles from northern exterior facing. Figure 15: Inventory chart of the pieces in the interior flooring.