DIGITAL TECHNOLOGIES APPLIED TO THE ACCESSIBLE MANAGEMENT OF MUSEUMS. THE FIRST EXPERIMENTS CARRIED OUT AT THE MUSEUM OF ORIENTAL ART OF TURIN

The proposed research focuses on the museum context of the city of Turin (Italy), within an ongoing framework agreement between the Politecnico di Torino and the Museum of Oriental Art (MAO). It aims at the construction of a model for the management of the workflow that includes the digital survey, the 3D virtual modelling and the digital fabrication of the tactile models of the artworks and the exhibition spaces. The paper starts with an overview on the methods of conservation and dissemination of cultural and architectural heritage, on the accessibility of museums and on tactile perception and graphics. It presents the first outcomes of the designed workflow with a special focus on the digital fabrication experiments on the vaulted system of the atrium of Palazzo Mazzonis (MAO home). The founding idea is that tactile exploration of artifacts helps the visitor engagement, making the museum experience more educationally incisive and more inclusive, in a “Design for All” perspective.


INTRODUCTION
In recent years, the development of 3D technologies has generated important results in the field of Cultural Heritage.
Research in this field has produced and continues to promote, on the one hand, the birth and creation of digital archives, with the consequent delocalization of works from the museum and, on the other hand, the realization of in situ accessibility projects, thus physically opening the doors to the widest possible audience.
Today, the availability of digital scanning and the process of digital design and fabrication opens up possibilities for automation that allow the reproduction of objects in different formats, facilitating access to cultural heritage. Museums represent the domain where the concept of CH 'usability' has always manifested itself, a perfect context to explore the enormous potential of these modern technologies, offering new experience opportunities.
Both virtual and physical products aim to increase accessibility to meet different needs of users related to different factors of age, physical, sensory and cognitive abilities, education, culture and experience. Extending CH accessibility to people with disabilities is a current issue of great importance. Physical, sensory, and cultural accessibility should be considered essential to making cultural venues fully accessible to all visitors.
The hypothesis of this research is based on the recognition of the benefits that the visitor can achieve through a multisensory and immersive visit path. The challenge consists in the identification of a workflow that begins with recording the shape of the object and ends with its physical reproduction. The main question is how to reproduce models and informational materials that are suitable to be explored and understood during the tactile experience. 3D models of statues or architectures are very useful tools to engage people, especially suitable for users with special needs, such as blind people, who rely on the sense of touch to perceive objects.
The overall goal is to propose a multisensory exhibition model that takes into account this often neglected audience, expanding the field of research on all the experiential possibilities of the museum offer, beyond the visual.

METHODS OF CONSERVATION AND DISSEMINATION OF CULTURAL AND ARCHITECTURAL HERITAGE: STATE OF THE ART
The state of the art of methods of conservation and dissemination of cultural and architectural heritage is closely linked to technologies available to researchers in recent years. The use of electronic equipment allows performing some very precise survey operations that do not replace the traditional procedures of data acquisition but enrich them recording higher-level information content. Digitization systems of works using optical technologies, ensuring the integrity of the surveyed works, are gaining more and more importance (Díaz Gómez et al. 2012: 29-37). These include 3D digitization techniques based on laser and light stripes projection, also called structured white light. The use of these technologies allows the acquisition of very complex shapes (also related to "free-form" geometries), data about the investigated surface (smoothness, roughness, etc.) and colour information (Bo et al. 2019: 1-11). An alternative to these optical technologies is photogrammetry, which creates 3D models from simple 2D images. Therefore, the required instrumentation simply consists of a camera, a tripod, and possibly a set of lights. This allows any person with a good computer and a good camera to create three-dimensional models with photogrammetry programs in fairly automatic way.
The point cloud, obtained through a process of photogrammetry or laser scanning, can be saved and archived, returning the real state of an object in a given space-time context, allowing manipulation and measurement without physical contact with it. The digital models obtained can be shared in several ways (Barberà Giné 2017: 153-162). One of the simplest methods is to create a .pdf file using the Adobe Acrobat® 3D visualization tool. Certainly, the most effective way for artistic heritage valorization is represented by online platforms, such as Sketchfab, which allow totally interactive and free fruition. Digitized works are also used for the creation of virtual videos/stories, often equipped with graphic information (Díaz Gómez et al. 2012: 29-37). These three-dimensional models, modifiable and reproducible, are also used for purposes of data collection, analysis, and expansion of museum offerings, through the experience of physical replicas (Balletti & Ballarin 2019: 285-313).

THE ACCESSIBILITY OF ARCHITECTURAL AND CULTURAL HERITAGE IN MUSEUMS
Since the end of the 21st century, communication and involvement of the public have progressively become central to museums.
In Italy, the 1971 conference "The museum as a social experience" decreed the end of the conception of the museum as elite heritage, paving the way towards a more democratic vision of access to culture (Bruno 2019: 297-325). This trend was subsequently confirmed at the international level by the UN Universal Declaration of Human Rights (art 27.1) and reaffirmed by the Council of Europe Framework Convention on the Value of Cultural Heritage for Society, the so-called Faro Convention of 2013 (Montella et al. 2016: 13-36).
In Spain, the association Organización Nacional de Ciegos Españoles (ONCE), founder of the Madrid Typhlological Museum, has been working for almost a century to ensure services for blind people or people with severe visual impairments. Among the research carried out by the association and its publications there are more general ones that deal with European policies about access to culture by people with disabilities and those related to museum accessibility for the blind and visually impaired, in which European case studies and project proposals for access to content and container are reported (García Lucerga 1993, Pérez de Andrés & Ramos Fuentes 1994).
Cutting-edge museum institutions are beginning to recognize modern technologies as a means of adding new methods of "reading" to more traditional visitor paths (Petrelli et al. 2013: 58-63, Wilson et al. 2017. Museums are increasingly offering multilevel and multisensory experiences, including not only sight, but also the senses of touch, smell, and hearing, which equally contribute to our knowledge of the reality around us. Contemporary museums pay particular attention to the manipulation of objects, whether physical or virtual, as it creates a stronger connection between the individual and the object than simply watching it.

ITALIAN RESEARCH
Several Italian scholars in the discipline of representation have carried out very interesting and multidisciplinary research projects on the study and modelling in 3D for museum exhibition purposes. Among them, particularly stimulating is the work carried out by Paolo Clini and his multidisciplinary research group at the Museo Archeologico Nazionale delle Marche in 2017 (Clini et al. 2018: 97-113). The proposed project is based on the fruition paradigm of "learning by interacting", which allows going beyond the traditional forms of presentation/observation of heritage through showcases, stimulating the visitor to become an active spectator. Overall, the project allows for a direct connection between traditional information and the digital "copy" of the artefact.
Another Italian reference in this field is the research conducted by Alberto Sdegno, at the Department of Engineering and Architecture of the Università di Trieste, on some significant works of art, using the most sophisticated declinations of research tools from advanced modelling to threedimensional scanning, 3D printing ( Fig. 1), and interaction experiences offered by Augmented Reality technologies (Sdegno 2018: 257-272). In the field of the discipline of Museology, the case of Museo Facile is particularly significant, a project conducted since 2012 by the Department of Humanities of the Università di Cassino e del Lazio Meridionale. This project focuses on communication and cultural accessibility, proposing an integrated system of communication that combines traditional tools with the use of teaching aids and assistive technologies (QR Code, video in Italian Sign Language LIS, thermoformed panels and tactile models) (Bruno 2019: 297-325). It is based on a rigorous study of the museum spaces to build an "easy" path able to meet the needs of different audiences. Interdisciplinary comparison and participatory planning represent the methodological premises of the project. The model has been tested and applied at the H.C. Andersen Museum in Rome, at the Museum of the Abbey of Montecassino and in the recent project "Luoghi del Contemporaneo a Cassino".

INTERNATIONAL MUSEUMS OFFER
Research about the main museums offers at the international level, with the exception of those specifically dedicated to tactile experiences (Museo Statale Omero in Ancona, Museo Anteros in Bologna, Museo Tiflologico in Madrid), reveals heterogeneous attention to tactile sensory accessibility.
Some museums simply allow small groups of people to partially touch the collection, often with the help of staff or escorts (Uffizi Gallery, Florence; Metropolitan Museum of Art, New York). In other cases, there are only descriptive tours with dedicated guides (Rijksmuseum, Netherlands; National Gallery of Art, New York). The Van Gogh Museum also offers a workshop, to be held in a separate room from the traditional tour, with a three-dimensional reproduction of the famous painting "Sunflowers". The Guggenheim Museum in New York takes the same approach, organizing monthly dedicated tours and workshops.
Others include some tactile supports (diagrams, Braille) or large print descriptions for the visually impaired that visitors can request at the ticket office or print directly at home (National Gallery in London, The Tate Modern in London). The British Museum offers, in addition to all this, the possibility of tactilely exploring nine works of the Egyptian sculpture gallery, through a "Guided Touch Tour" or independently, with support material provided at the ticket office. This museum also provides audio descriptions that can be downloaded from the website and listened directly from the user's smartphone.
The Louvre in Paris provides a specially designed Touch gallery (handrails all along the way, plaques in Braille, French and English) that houses replicas of ten sculptures in a space specifically designed to ensure accessibility, even on their own, for the visually impaired user. This gallery is not separate from the rest of the museum and is open to anyone, representing an educational space useful to all.
In 2015, the Museo Nacional del Prado in Madrid launched the Touch the Prado exhibition that included the possibility of touching the relief images of six pictorial works of different genres, as well as enjoying educational materials (Braille texts and audio guides).
In 2018, the National Gallery in Prague hosted the temporary exhibition "Touching Masterpieces by Geometry" in which digital models of some iconic sculptures (Michelangelo's David, Venus de Milo, and Nefertiti) could be tactilely explored with special haptic gloves that control the hands in virtual space, returning vibrations when the object is intercepted.
The permanent exhibition at the Louvre in Abu Dhabi is particularly interesting. Opened in 2017, it houses different haptic stations, created by "Tactile Studio", containing a description of the represented object, to which a Braille translation and a reproduction of the tangible object are added. On the panel, there are also some enlarged details of the object, to guarantee and facilitate its fruition (Fig. 2).
Apart from the last example in Abu Dhabi, the approach is often to treat the tactile experience as something separate from the normal visit. This probably occurs both because attention to this type of accessibility is a relatively recent issue that many museums have found themselves dealing with in the process, and because there are no shared guidelines in this regard. • 3DPhotoworks (Photoworks n.d.), a U.S. company, which produces colored tactile prints that, for the "Sight Unseen" exhibition at the Canadian Museum for Human Rights, incorporated tactile sensors that trigger sound descriptions; • The University of Vienna (Candling 2010) conducted research on converting 2D and 3D artefacts into tactile replicas, which were then enhanced with an audio guide, tactile guidance system, and relief diagrams; • Applications that used 3D printed interactive models equipped with sensors such as cameras (Reichinger 2016: 91-100), capacitive sensors, and microphones (Shi et al. 2016: 4896-4907); • The "Orasis" project uses 3D printed exhibits, connected tactile sensors, Arduino boards, and a mobile app to improve museum access for blind users (Anagnostakis et al. 2016: 1021-1025); 3D puzzles from the "Brighton Museum and Art Gallery" that focus on the educational purpose of replication and the educational and communicative aspect of the CH experience, proposing a playful use of it (Samaroudi 2017: 201-206).
These experiences testify that, without a doubt, one of the goals of applied research is to create "sensorized" models (Reichinger 2012: 497-504). Replicas and digitally fabricated models must increasingly be joined by other technologies to create significant added value in the museum context, confirming the need for a multidisciplinary approach to ensure the greatest possible accessibility to museums and cultural heritage in general.
These examples represent a point of reference for this research, offering didactically "interactive" paths, through the integration of different representation tools and giving space to moments of tactile exploration.

NOTES ON TACTILE PERCEPTION AND THE VALUE OF MANIPULATION AS COGNITIVE TOOLS
Touch is a realistic, concrete, and sequential sense and is considered the sense that first induces us into the world and last leaves us. The similarity between tactile and optical behaviors calls for a careful examination of the compensatory processes of the human mind, especially when integrated use of the residual senses replaces vision. Through the contact of the hand with lines, surfaces and volumes in relief it is possible to redraw an image and to know a composition. In the mind vision is elaborated from the connection of sensory perceptions and knowledge, whether its optical or tactile nature (Secchi 2018: 15-31). Tactile perception becomes of fundamental importance for blind and visually impaired people, assuming a gnostic function and becoming a real active tactile exploration, systematic and intentional, also called haptic exploration. It involves harmonious coordination of the two hands in place of the hand-eye coordination of the sighted.
Haptic exploration takes longer than visual exploration because it requires a sequence of perceptual acts that are synthesized only later in a global representation.
Because of the peculiarities of the specificity of haptic perception, several scholars have addressed the issue of representation and relief graphics, trying to systematize and codify it.
The growing interest in tactile representation or "relief drawing" has produced numerous studies and research to establish what should be the basis of a unified codified language (Empler 1996).
Starting in the 1990s, in Italy, in the scientific disciplinary field of "drawing" there have been several studies and publications on the perceptual and representational modalities for the visually disabled (De Rubertis 1996, Levi & Rolli 1994, Brie & Morice 1996.
In the new millennium, the interest in these issues is confirmed by the studies of Lamberto Nasini and Hasan Isawi (Nasini & Isawi 2006 In the normative field there are now several ISOs concerning the "normalization" of characters and symbols, however, emerges a certain heterogeneity of research areas and results that affect the field. To date has not yet reached a codification of the system of signs and meanings attributed to visual-tactile messages used and an organization of the same visual-tactile panels.
Communication for the visually impaired and blind has not yet had an effective procedural and graphic systematization; for this reason, a "system of codes" is necessary both for threedimensional and two-dimensional models, for which methodologies and methods of execution must be identified.
The definition of a codification of visual-tactile symbology requires an in-depth knowledge of the characteristics of the sense of touch, with particular reference to haptic perceptibility, and of the mental processes of memorization of information acquired by a visually impaired person by that means.

THE RESEARCH FRAME
The proposed research focuses on the museum context of the city of Turin (Italy), within an ongoing framework agreement between the Politecnico di Torino and the Museum of Oriental Art (MAO) that aims to build an accessible exhibition route that includes tactile models of the architectural spaces and a small part of its collection.  (Fig. 3), the staircase and the hall of honor of Palazzo Mazzonis, home of the MAO.

THE RESEARCH AIM
The research project is therefore inserted in this gap of the exhibition offer. After a careful analysis of the technologies for surveying and digital fabrication, of the studies and applications of multisensory pathways in museums and perceptive modalities beyond the sight, the main aims are: • the identification of a workflow that starts from the digital acquisition and has as its objective the realization of a tactile model/ replication made with the techniques of digital fabrication; • the realization of an inclusive and multisensory exhibition path, modular and implementable, including the description of the architectural/ exhibition spaces and a selection of works.

MAO: THE "CONTAINER" AND THE "CONTENTS"
MAO is one of the most important and dynamic realities in the Italian panorama in the field of presentation, valorization and diffusion of Asian arts and cultures.
It is located in Palazzo Mazzonis, a baroque building (1639) that, during the 18th century, after various interventions, assumed the current shape. It is constituted by a central part and other two parts embracing the central inner courtyard, linked to the road by a great colonnaded atrium. This atrium, adorned by an elegant stone colonnade, is connected by a sumptuous two flights staircase to the hall of honor at the first floor. These spaces are the only ones that have largely maintained original structure, even if with some modification to the decorative apparatus.
Regarding the content, MAO today boasts a collection of 2500 works coming from many countries of Asia and belonging different historical periods and 1400 finds from the excavation of archaeological sites in the Iraqi areas of Seleucia and Coche, from the pre-Islamic period (up to before 63 B.C.). To manage this vast heritage, the collection has been divided into five macroareas (South Asia, Southeast Asia, China, Japan, Himalayan Region, Islam), according to the historical and geographical belonging (Bruno & Ricca 2010: 3-24).
Since its opening to the public at the end of 2008, MAO has paid attention to digital technologies for the communication of its heritage, particularly at a distance. It is present on the web in various forms (dedicated website, social pages, YouTube channel, Google Arts and Culture). On the other hand, the visit in presence of the permanent collections of the MAO makes limited use of multimedia elements (audio guides) and does not include the use of other supports that would guarantee inclusive access (tactile models, dedicated audio descriptions, descriptions in LIS language).

THE WORKING METHODOLOGY AND PARTIAL RESULTS
The proposed workflow is appropriate for both the container (exhibition spaces) and the content (artworks) of the museum. It starts from the digital survey of the object arriving at the digital fabrication of it, passing through the 3D virtual modelling.
The project includes the before mentioned architectural spaces and five artworks (one for each geographical collection area) selected following these parameters: maneuverability and inspectability; illuminability; roughness; perceptibility of details; opacity; chromatic richness ( Fig. 4).
The following step is the digital survey and its return in virtual model. The survey was done with two different techniques: photogrammetry for the works (Fig. 5) and terrestrial laser scanner (TLS) for the spaces (Fig. 6).
Currently, the fabrication of the artworks' replicas hasn't yet begun. On the other side, a virtual model and two types of digitally fabricated models of the atrium vaulted system have been realized.
The maquettes, both at a scale of 1:50, consist of "illustratives" models, morphologically similar to the object acquired, instead of its exact copy. The virtual and physical modelling has been started from the cutting of the point cloud with 22 section planes (Fig. 7, Fig. 8).

FRANCESCA RONCO
In the first model, these sections have been transformed in real tangible interlocked planar slices. Such slices have been fabricated with the 2D cutting device Trotec Speedy 400® of ModLab Arch of Politecnico di Torino, employing relatively inexpensive material (such as cardboard) and then assembled through a sequence of manual operations (Fig. 9, Fig. 10).    This model, with a purely didactic function, emphasizes the perception of the vaulted system of the atrium from bottom to top (Fig. 11), but observing the waste material of the cutting process, some considerations can be done. A new model with the voids and solids reversed can be designed. In this way, the user could perceive the surface from above. The second model is based on this observation, in the perspective of tactile fruition.
In the second model, sections have been used to build the virtual 3D interpretative model with Rhinoceros® 7. The spaces are represented in negative to obtain a handy object that allows perceiving the intrados surface of the vaults from above.
Each of these parts (except the arches) was then subdivided into additional portions for fabrication constraints, to facilitate its realization with a numerical control milling machine. The need was to have at least one flat face to place on the work plan and to avoid moving or rotating the machined piece for further operations. The division operations were carried out manually, even if algorithms for automatic division exist (Muntoni et al. 2019: 17-28). The solids of the various portions have been cut with horizontal planes, at a different distance according to the thickness of the MDF panel to be used (10, 14 or 1 mm).
The Medium Density Fiberboard (MDF) model has been fabricated with Biemmepi -FP3 CNC milling machine.

FRANCESCA RONCO
For each portion of the atrium, a single block has been obtained through the assembly phase. The final model will allow both a global perception of the surface of the vaulted system from above (assembled configuration) and a deeper understanding of the geometry of the single vaulted portion (divided configuration) (Fig. 13).

CONCLUSION
This research aims at the construction of a model for the management of the workflow from the digitization of the work and the exhibition spaces to the realization of the tactile replica. Currently, we are facing a lack of research about workflows and methodologies of creation of such replicas, leaving open many questions about issues like scale, choice of materials and even ways to present them to the public. The physical properties of the replicas and ways of presenting them to the public must be adequately addressed prior to the implementation of this large-scale approach (Wilson et al. 2017).
From a social and economic perspective, there is no question that tactile exploration of artefacts helps the visitor understanding and engagement. In addition, the tactile experience accompanied by audio descriptions, holds great value making the museum experience more educationally incisive and more inclusive, in a "Design for All" perspective.
The sense of the creation of a model and a shared language is to reduce the errors of assessment by museum institutions on accessibility issues and to facilitate users in the tactile experience so that it becomes increasingly automatic and does not require introductions and explanations.
Here I have presented the early stages of this research. MAO represents a great opportunity to test different digital survey and fabrication techniques, at different scales.
The prototypes presented have two different purposes, the first (sliced one) has a more didactic function, explanatory of the geometries generating the vaulted system, the second goes in the direction of tactile enjoyment. Obviously, once its effectiveness has been established, the second model will have to be enriched by tactile graphics and accompanied by audio descriptions, similarly to what previously presented.
The obtained models will need to be continuously tested by visually-impaired people and, thanks to the help of Dr. Franco Lepore, Disability Manager of the Municipality of Turin, and Arch. Rocco Rolli, founder of Tactile Vision Onlus, test groups will be constituted to verify the effectiveness of all the tactile models produced.