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The Temart project: methodologies and technologies for 3D printing of tactile reproductions. By Maria Stella Busana and Francesca Farrono Gallo

Maria Stella Busana – Professor of Roman Archeology, Cultural Heritage Department of the University of Padua
and Francesca Farroni Gallo – archeologist specialized in museum accessibility
.

The TEMART Project (TEMART – Technologies and materials for artistic production, cultural heritage, furnishing, architectural and urban decor, and the design of the future) is a research project funded by the Veneto Region within the context of the Por-Fesr (2014-2020) proclamations, and which has involved the business world (four Innovative Regional Networks: 3M Net, the project leader, Venetian Cluster, Euteknos, Luce in Veneto) and  research bodies through the Univeneto Foundation (Universities of Padua, Venice “Ca’ Foscari”, Verona, IUAV) with the aim of strengthening links between research and local enterprise.

The main part of the TEMART project has focused on industrial case studies.

The Cultural Heritage Department of the University of Padua, on the other hand, has conducted groundbreaking research on archeological and artistic artefacts. The work was  carried out in conjunction with research groups from Padua University’s Department of Industrial Engineering and from Verona University’s Department of Computer Science and from the Department of Environmental Sciences, Computer Sciences and Statistics of Venice Ca’ Foscari University, acting in synergy with three business consortiums: 3M Net, ECOR and Venetian Heritage.

The sub-project, promoted by the Cultural Heritage Department, coordinated by Professor Maria Stella Busana, was carried forward by Giovanna Baldissin, Giuseppe Salemi, Monica Salvadori, Emanuela Faresin, Francesca Farroni Gallo, Cecilia Rossi, Clelia Sbrolli e Luca Zamparo.

The main aim was  the validation of protocols to obtain replicas with a view to exploiting the artefacts to the full: a) a fairly mechanical reproduction for use by everybody, and b) a reproduction for use by people with visual impairments.

Hence the focus of the project was on digital surveys through scanning and 3D print reproduction of a number of artefacts which differed in terms of technical and material characteristics but were alike in their considerable formal and chromatic complexity.

The availability of 3D reproductions actually facilitates the temporary loan of the originals or the display of artefacts housed elsewhere, and enables the creation of inclusive tactile routes.

Though aware that direct contact with an original work of art or an archeological artefact is undoubtedly the more meaningful experience, the exploration of replicas through touch is also an excellent opportunity to discover the work, especially for the visually impaired.

In order to contribute to the debate on an extremely topical theme, and to be guided in the methodological and technological decisions pertaining to the TEMART project, two pieces of research were planned right from the outset. They were conducted by Francesca Farroni Gallo and Clelia Sbrolli and designed to explore the specific needs of the users of the reproductions: on the one hand, a survey of the practices adopted in museums in Italy and abroad, paying attention also to the public’s response and to any problems which emerged; on the other hand, tactile tests on the two series of casts of the Donatello reliefs exhibited at the Museo Antoniano of the Basilica del Santo in Padua, with the participation of the Italian Union for the Blind and Visually Impaired of Padua.

The survey enabled us to examine 55 museums with tactile itineraries, 44 in Italy and 11 abroad, and to specifically classify them. What emerged was a considerable variety of approaches which can be grouped into four categories:

–          itineraries with original works (mainly statuary and ceramics)

–           tactile stations with reproductions or casts, adopting a range of methods to highlight the different concepts to be conveyed

–          itineraries with reworkings of the artworks to make them accessible to people with visual impairments (mainly tactile panels of paintings)

–           mixed itineraries, including original artworks and reproductions/casts or reworkings.

The sample of foreign museums, although limited, included 6 museums which had opted for itineraries with reproductions and casts, 4 with originals and reproductions, and only 1 with reworkings of the artworks.

The Italian situation is different: 11 museums provide originals, 13 have a mixed itinerary with originals and casts, 10 offer a route with reworkings of the artworks, 8 museums have devised a tactile itinerary with reproductions and casts, while only 2 offer routes with just reworkings of the artworks. The reproductions are usually created using 3D printing and manual finishing techniques to obtain replicas which are as realistic as possible, not least to the touch.

The choice of one type of itinerary rather than another is often dictated by the museum’s permanent collection: in Italy the high percentage of tactile access to the originals is partly determined by by the predominance of statue collections; painting collections require reproductions capable of decodifying a pictorial language inaccessible to the visually impaired.

A recent project in the Veneto Region may serve as an example.

In 2019, as part of the “Antenati Altinati” exhibition,  the National Museum and Archeological Area of Altino and the Associazione Lapis carried out a project entitled “Tocchiamoli con mano” (Let’s touch them with our hands”). Within the exhibition area, the use of part of the original Roman funerary monuments, together with a “tactile panel” reproducing a Roman funerary relief, meant that it was possible to organize monthly visits and workshops for people with visual impairments, temporarily blocked due to the pandemic.

The experience of the tactile tests organized with members of the Padua branch of UICI (Italian Union for the Blind and Visually Impaired), while highlighting the difficulty of drawing up common guidelines, due both to the exploratory capacities of each member and the different materials used for the replicas, provided information essential to taking informed decisions about the project.

This experience enabled us to test the clarity of the historical casts, which turned out to be greater if supported by an initial explanation and/or by simplified tactile panels, and to realize that reproductions on a scale of 1:1 were preferable, possibly supplemented with didactic supports, detail enlargements or simplified versions. It also became clear that it was more important for the reproduction to be made in materials which are pleasant to touch than in the original material, though the original matrial can be present in the form of a small block to make the experience more complete.

As regards accessibility, the TEMART project focused specifically on one case study: the bronze relief panel of the Dead Christ, made by Donatello around the middle of the fifteenth century and now placed on the high altar of the Basilica del Santo in Padua. The choice fell on this particular work becuse of its exceptional artistic merit and because of the difficulty of fully appreciating it since the altar is not accessible to the public.

In the light of preliminary research into the condition of the panel, and following a visit with Padua UICI members, the working party decided to proceed with a digital survey and subsequent 3D, 1:1 scale, print of the panel in different materials, as well as producing a detail on an enlarged scale. Experiments were carried out at the same time with different surface treatments, with a view to achieving results which were both hygenic and pleasant to the touch.

Specifically, the panel of the Dead Christ was obtained by using three different technologies and obtaining three-dimensional models with different characteristics: laser blade scanning, performed by Ecor International; structured light scanning, carried out by the Cultural Heritage Department of the University of Padua, which obtained the most complete survey and the one especially suitable for three-dimensional, physical reproductions; and conoscopic holography microprofilometry, using a prototype from the Department of Computer Sciences of Verona University which proved effective in acquiring details and assessing the state of conservation of the panel.

The processed files were used to create 1:1 scale prototypes in both metallic and polymeric materials and to assess the technologies to be used in the surface treatment stages, such as the varnishing of the polymetric reproductions and the finishing of the metallic ones.

The scanning carried out with a structured light scanner has been described by Giuseppe Salemi and Emanuela Faresin in an article due for publication in the review “Il Santo”, “Percorsi tattili per i beni archeologici e artistici in Italia e all’estero: il progetto TEMART e il Cristo passo di Donatello” (“Tactile routes for the artistic and archeological heritage in Italy and abroad: the TEMART project and Donatello’s Dead Christ”). This technique enabled us to acquire data by projecting onto the object patterns of light which, by changing according to the morphology of the panel’s surface, made it possible to determine a trio of coordinates x, y, z, where z is the distance of the point from the instrument. During the scanning, the chromatic information is also recorded, making possible a very high resolution, photo-realistic, 3D model, which can be used for various purposes and reworkings.

As explained by Nicolò De Marchi in the above-mentioned work, the subsequent printing involves first the transformation from real to digital and then again to tangible. The risk is that, in moving from one stage to the next, some details of the work may be lost or rendered without the necessary faithfulness to the original. The 3D relief file is divided into planar sections in an operation known as “slicing”, where the thickness of the sections is determined by the capacity of the system which effects the slicing: the more accurate the printer, the thinner the strata. Once the printing is finished, a number of operations are required to clean the surfaces, remove the support structures, or assemble the various parts.

To reproduce the Dead Christ, the Industrial Engineering Department of Padua University decided to use Polyjet technology, which is comparable in terms of function to two-dimensional inkjet printing. Similar to normal printers, Polyjet technology uses small nozzles to spray tiny droplets of polymer to form the first layer. The operation is repeated each time to create successive layers of polymer. The material solidifies layer by layer under UV light. This technology requires a support to hold up the geometry of the print before the reproduction is complete. Polyject technology makes use of a gelatinous support which can be removed with a simple jet of water once the reproduction is finished.

The most critical issue was the size of the panel, too large to be produced with a single print of the machine in question. Careful research work resulted in the panel being printed in several sections and only later joined together along lines which were already present in the work, such as the drapery or the outlines of the main figures. This solution made it possible to disguise the joins between the various parts to the point that they are all but imperceptible.

Additional printouts were made by the Computer Science Department of Verona University and Ecor. 

Venetian Cluster then ran positive and negative samples to test the feasibility of mass reproduction based on industrial products.

The procedures carried out as part of the TEMART project demonstrate how an interdisciplinary approach makes it possible to test different methodologies and technical options so as to identify the best solutions for making 3D reproductions of cultural heritage artefacts to be enjoyed by people with visual impairments.

Si auspica di poter realizzare in futuro test di verifica finale dei prototipi con i partecipanti dell’Unione ciechi e ipovedenti di Padova della prima visita, non attuati a causa dell’emergenza sanitaria, per poter capire l’effettiva bontà delle riproduzioni realizzate e quali di queste offrono i risultati migliori, al fine di individuare, sempre più nel dettaglio, un protocollo applicativo utile alla realizzazione di riproduzioni accessibili dei beni culturali.

It is hoped that it will be possible in future to carry out final tests on the prototypes with the members of the Padova branch of the Union of the Blind and Visually Impaired who made the initial visit. So far the tests have not been conducted because of the pandemic, but they will prove extremely helpful in understanding the effective usefulness of the reproductions and identifying those which offer the best results. That feedback will allow us to devise, in ever greater detail, an application protocol for creating accessible reproductions of items of our cultural heritage.