When designing a phantom test, a researcher attempts to create a controlled environment which replicates a well defined but limited subset of the characteristics of a larger problem. Typically, a phantom in medical physics will include a simplified environment which simulates a patient, or part of a patient such as an organ or similar. The conditions in the experiment are controlled, thus the performance of a system can be tested thoroughly and compared to a known ground truth before testing it on a real patient. This simplified environment provides a fast and robust product development cycle which is independent of concerns about the safety of a patient.

 Phantoms can be either a computer simulation of a digital model mimicking a real object on which one can test processing algorithms, or specially designed material objects mimicking specific characteristics of a real object. For example, often in medical imaging phantoms are produced from materials that mimic human tissue but with well-characterised material properties. The phantom can then be imaged with a new experimental technique, providing useful insight into the performance of the new technology. The construction and characterisation of phantoms is an important area of research.5 For example, Price et al.6 have developed a material that simulates breast tissue. This material was developed specifically to respond to breast compression and X-rays in a similar way to breast tissue, so that it can be used by researchers to study the performance of new X-ray imaging techniques. Ionising radiation is dangerous to humans, and phantom materials such as this ensure that the patient is exposed to it only when necessary. Similarly, Levesque, Sled & Pike7 present an iterative design methodology, aided by a phantom, to optimise systematically, and improve the signal to noise ratio of quantitative magnetisation transfer imaging, a specialised medical imaging technique. Tests can subsequently be performed directly on the patient once the technology and its effects are better understood.

The tradition of phantom development and testing has not yet become established as a research methodology in the humanities. In the world of conservation, and heritage science in particular, however, where new techniques are developed for the assessment, treatment, or recovery of cultural artefacts, the use of controlled degradation and synthetic and virtual models is more common.8 These tools are used with a similar purpose to that of phantom tests. Examples vary from the determination of the degree of deterioration of parchment samples through comparison with new, artificially-aged, and naturallyaged parchment,9 to the quantification of the deterioration effects of light damage on parchment through controlled UV irradiation on modern parchment tested before and after irradiation,10 to the aging characteristics of gelatines and animal glues used in conservation and their reversibility through tests on newly produced adhesive films.11 These experiments are not directly named as phantoms, but their execution is intended to perform a similar function: testing, comparing, optimising, and validating methodologies. Recently research appears to have begun explicitly utilising phantoms as research tools. Marengo et al.12 use virtual degradation of multispectral images of documents in order to evaluate an algorithm in controlled conditions. The algorithm they developed monitors the conservation condition of a document, based on information from multispectral images of the document. They manipulate the data in specific ways in order to train the algorithm, which they later apply to unadulterated images.

Finally, recent work in scrolled historical documents has used modelling and problem simplification to develop algorithms to digitally unroll and reconstruct the writing from scanned images of the documents. Scrolls that are too fragile and deteriorated to be physically unrolled present a difficult imaging problem, as most of the text is within the scroll and often is present on both sides of the parchment. Sub-surface imaging techniques have been used to scan these documents, but the writing typically remains illegible. Developing algorithms to digitally unroll these documents is challenging, but the use of laboratorycreated scrolls and digital models is proving to be more and more successful.13

In this project, we proposed a new method for assessing the effectiveness of image processing algorithms that are currently in use to recover information from degraded documents. The first step was designing and implementing a virtual model phantom to simulate the conditions that are common to palimpsest manuscripts. Figure 1 shows how we constructed a phantom simulation

**Figure 1:** A series of artificial material layers were used in order to construct a virtual model phantom of a palimpsest. By composing the elements in known ways, a method for testing the accuracy of the extraction was devised. Left: materials layers used to compose the phantom. Right: simulation of multispectral images of the phantom based on the material layers (Giacometti 2013). generated multispectral images with two layers of text, a background layer and a staining layer. A series of image processing algorithms were used to separate the components. *A priori* knowledge of the materials that contribute to the document and their arrangement in the document provides a ground truth which enables the evaluation of how the image processing algorithms perform at recovering the writing from the document. Once a basis for a comparison was available, we were able to propose a method to compare images of recovered information to the ground truth. The phantom was essential in devising an appropriate method to measure that performance. The method proposed later proved capable at handling experimental data. The phantom was based on methodologies from medical physics research. It was only able to be constructed once specific characteristics of palimpsests where understood and in the context of previous experimentation in conservation.

# **3 Case Study 2: Historically accurate modelling of parchment damage designed for imaging purposes**

A second example is the design of a methodology to physically model macroscopic damage to parchment to provide a test platform for multispectral imaging processing algorithms. Following the hands-on approach typically found in conservation research, we identified the different types of damage parchment documents are likely to incur during their lives, from technological mistakes during production, to improper use, unsuitable storage condition, disasters, and natural ageing;14 we then subjected an original parchment document to a series of treatments aimed at mimicking these deterioration processes. Careful consideration was given to select this set of deteriorating agents which required expertise from conservation and image science.15

Accredited archives follow strict guidelines and policies on the deaccessioning of items from their collections. Whilst historical collections are usually preserved, on rare occasions, such as when material is duplicated, non-archival, or of no informational/evidential value, they can be deaccessioned, and disposed of by being transferred to other repositories, returned to owners, sold, or destroyed.16 Historical items sent to be destroyed may still be of substantial value as physical objects and may be donated to conservation studios or conservation training centres for experimentation and training on historical materials without risking damaging items of incontestable documentary value. We obtained, through this route, an 18th-century parchment document, deemed of no historical value, and deaccessioned from the London Metropolitan Archives' collections in accordance with The National Archives guidance on deaccessioning and disposal.17 Dated to 11th of August 1753, it is an indenture, or land contract, between a Mr John Sherman and a Mr Christ Gardiner. Apart from some signs of wear and tear, especially around the fold, the parchment document was in overall good condition. The text had been handwritten in metallo-gallic ink on the recto (flesh side), with some information recorded also on the verso.

We chose to focus on parchment documents for our study, given that parchment remains the primary medium of large quantities of culturally important documents in archives, museums, libraries, and private collections. Parchment, prised for its durability and versatility, and used as writing support for centuries, is a material, constituted of structured collagen fibres that is extremely hygroscopic and reacts readily to changes of humidity, resulting in cockling and curling, and is endangered by biological, thermochemical, and mechanical damage.18 We identified twenty methods of degradation that commonly affect parchment documents, changing their physical characteristics at both microscopic and macroscopic levels.19 The damage agents were selected so as to affect the properties of the parchment, but also the legibility of text in various ways, for example, shrinking or otherwise deforming the parchment, and obscuring or effacing the writing via physical, chemical, or biological reactions.20 These degradation methods fall within the main categories of (a) mechanical, (b) thermochemical and humidity, and (c) physical and extraneous substances, all of which act directly upon the writing support, changing its physical characteristics at both microscopic and macroscopic levels. Table 1 summarises the effects of a selection of the damage treatments,21 and Table 2 puts the treatments into context with the possible causes of damage that can occur to parchment documents during their lives.

In Table 2, the damage categories—*mechanical, thermochemical and humidity, physical and extraneous substances*—highlight what was mainly and primarily affected during the deterioration inflicted on the samples. In conservation, causes of damage are conventionally categorised in discrete groups, even if these are necessarily interrelated, focusing on the main source of damage. For instance, biological damage is caused by mould growing on the material, or insects eating through the material, but for mould to grow, or insects to be lively, the environmental conditions need to be within certain parameters − i.e. high relative humidity and relatively high temperature; at the same environmental conditions the material could already be suffering at the microscopic

**Table 1:** A selection of methods used to degrade the parchment.

**Table 2:** Summary of different types of degradation (in small capitals), giving the reason for the degradation, the circumstances in which it might occur and the type of degradation. In the table are also highlighted the kinds of degradation that naturally occurred to the manuscript during our experiments; these are identified by the keyword *Controls.* In bold, treatments from Table 1. (Giacometti, et al*.* 2012a). level, but these factors are shadowed by the impact of external living organisms on it. Also, when mould grows on paper and parchment, the deterioration process is certainly caused by the chemical reactions following digestion, but deterioration by mould is still usually classified as biological and not chemical damage. In the literature, however, damage classification systems vary from publication to publication: there is no universal standard on damage categorisation and its terminology.22

Additionally, we group damage agents that would have similar macroscopic effects on the parchment samples, and that would thus have similar spectral characteristics.23 In some cases, at the macroscopic level, in our experiments, we have damages that have to be signalled as belonging to more than one category—e.g. any liquid would have similar impact on parchment, but with different overall final result depending on the liquid: all liquids, from neutral water to ink, would have resulted in cockling of the sample and similar physical effects, but inks would have also obscured the writing on the sample, whilst other fluids would have also affected the parchment chemically. The categories help creating subgroups when damaging agents belong to the same group of damage category. We thus group together damages that are usually considered separately in conservation studies, as our groupings highlight similar spectral responses, which is not usually a grouping criterion for conservators. For our purposes, the damage categories can be defined as follows:

*Mechanical damage***:** a physical deterioration originating from a physical force applied to an object, e.g. rubbing, folding, tearing − mostly affecting the legibility of the object but without compromising the chemical structure. This can sometimes provoke changes in the object's structure.

*Damage by chemical, biological, or environmental factors:* damage caused by substances that react with the original material resulting in a chemical change. Environmental factors such as light, humidity, and temperature can also provoke changes on an atomic or molecular level. The damage is caused by hydrolysis, oxidation or photochemical processes. Biological damage concerns damage to objects caused by living organisms such as moulds, insects, rodents and other living creatures.

*Damage by extraneous substances:* foreign substances introduced to an object disturbing its legibility.

Once we identified the types of damage that we were going to apply to our document, we cut twenty-three 8 × 8 cm flat square sections from the two pages of the document, each containing written text and avoiding folds (see Figure 2).

The samples were imaged before and after being damaged, thus making it possible to evaluate the efficacy of imaging processing algorithms in recovering the writing from parchment documents suffering from various forms of damage.

Outer Leaf

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**Figure 2:** A diagram of the location of the samples cut from both leaves of the iron gall ink on parchment manuscript. Each sample is 8cm square, giving an overall impression of the size of the original parchment (Giacometti 2013).

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This experiment was approached from a highly multidisciplinary perspective, applying a methodology taken from medical imaging to a problem in conservation. Expertise in medical imaging and conservation was combined with insights from colour science, chemistry, and image processing in order to develop standardised tests to inform the development of multispectral imaging.

# **4 Case Study 3: The do-it-yourself spirit of the materials, equipment, and procedures**

As the project developed, it became clear that the multispectral images had to be acquired within the project's limited budget. Expertise means having the know how on a subject, and being able to simplify problems and foresee experimental results.24 In other words, this required an active collaboration with experts from all the domains involved in order to obtain the necessary materials and equipment. As a consequence, this entailed a *do-it-yourself* approach to the production and the acquisition of the experimental data.

#### *4.1 Data production*

We were fortunate to be based in a medical physics laboratory, which offered access to basic laboratory equipment and materials, such as a fume cupboard, computer-controlled oven, laboratory glassware, scalpels, nitrile gloves, pipettes, pH indicators, as well as chemicals, human blood, and so on.

As mentioned above, our connections with the conservation world allowed us access to an original, 18th-century parchment document on which to experiment. We cut it into square samples and proceeded to inflict on these the series of damaging procedures illustrated above.

The experience accrued during conservation training and over years of bench work in conservation studios allowed us to optimise the damaging procedures so as to ensure that we limited the effects of each treatment to a single agent or procedure, e.g. we wanted to see the effect of the heat suffered in fire from the smoke. This was an important factor to take into consideration for the production of the physical samples to image: the difference between the images acquired before and after damage had to be well understood for the data analysis to be meaningful, reproducible, and comparable to other exemplars and samples. This required a number of creative solutions that were devised in an ad-hoc manner. Carefully considering the requirements for each one of the procedures, we fashioned simple devices or procedures that allowed us to perform the treatment within our budgetary constraints.

For instance, when parchment is exposed to high temperatures, its collagen structure goes through drastic changes with significant impact on the overall appearance and topography of the sample's surface: heat above 200°C removes most of the water from the collagen structure, it denatures and turns it into a random structure, shrinking and coiling the parchment, which solidifies into a new three-dimensional structure, and becomes extremely brittle, making it impossible to flatten it again.25 Such a drastic series of changes would have made it extremely difficult to register images taken before and after heating, meaning that we could not be sure that a pixel in one image corresponded unambiguously with the same pixel in another. We therefore had to devise a method to expose the parchment sample to heat, causing its collagen structure to change, without radical changes in the three-dimensional structure of the sample. With this in mind, we placed the parchment sample between two Pyrex® Petri dishes, one inside the other; inside the top dish we placed a series of metal weights (up to about 1 kg), whose purpose was to weigh down the parchment, thus impeding its warping in the third dimension. As a result, as the parchment shrivelled and shrunk in the computer-controlled oven at 225°C, but the trays kept it flat and ready to be imaged (see Figure 3).

Fires in archives and libraries have devastating effects on parchment documents not only for the intense heat to which they are subjected, but also because of smoke stains and soot: particles and dust affect the document's legibility by obscuring text and reducing contrast.26 Following the principle of isolating different causes of deterioration, we prepared another sample for cold smoking, thus delivering smoke without the effects of heat on parchment. A smoking environment was devised – inspired by instructions from an amateur smoking online community27—using a soldering iron, an empty tin, smoking wood chips, aluminium containers, linen thread, and a large plastic box with lid (Figure 4). A hole was drilled on the side of the base of the tin, in order to insert the tip of the soldering iron. The tin was filled with wet wood chips. A linen thread mesh was hand sewn through the aluminium container to create a suspended base for the sample to rest on while being smoked. The components were then placed inside the plastic box to contain the smoke, creating the smoking environment. The soldering iron creates constant heat and slowly burns the wood chips. The sample was left inside the smoking environment for a total of nine hours. The smoke drastically discoloured the parchment, more intensively on the recto, which was facing up, than the verso (see Figure 5). The discolouration pattern on the verso suggested that the smoke penetrated from the recto more prominently through the weaker parts of the parchment (pores, old folds, blemishes).

Documents stored in a damp environment are quickly affected by mould growth. As moulds grow, they feed on dirt particles, and the organic compounds of parchment and inks, leaving coloured stains due to the chemical byproducts of the digestion process. Consequently, parchment documents affected by mould are fragile, porous, and often left with permanent discolourations which can be extremely intrusive—and, in the worst cases, holes. In order to

**Figure 4:** Smoking device constructed in order to treat the selected sample. Its construction was inspired by devices created by amateur smoking enthusiasts sharing their expertise online (see note 27; Giacometti 2013).

accelerate mould growth, a parchment sample was placed inside an airtight plastic container on top of a stack of damp blotters along with a slice of mouldy bread. Moulds that typically grow on bread, such as those of the genera *Aspergillus* and *Penicillium*, as proteolytic fungi, also affect parchment documents.28 The sample was left inside the container for approximately five weeks in a dark environment at stable room temperature. At the end of the incubation period, the sample presented the characteristic coloured stains, it was rather fragile and porous, and in places it had been completely destroyed (Figure 6).

Limiting the degradation effects by isolating them, whenever possible, allowed for more useful samples for the subsequent imaging process. In a similar way, we had to devise a way to allow successful alignment of the images before and after degradation. In order to create stable reference points for such a registration process, we decided to punch four 1 mm holes using a *Japanese screw punch* into each sample at about a third of the distance from the borders, thus forming a square of holes in the centre of each sample (Figure 7).29 These holes were later used to visually compare the images of the samples.

O512R

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**Figure 7:** One mm holes were punched into each sample, used as a calibration mark that would survive the conditions that every sample was being subjected to. These images show the difference in resolution of the two cameras used by displaying the punched holes at a similar scale (Giacometti 2013).

A card stencil, the same size of the samples, was used to keep the shape of the square consistent across the samples. These holes were chosen as an effective registration method as they did not affect the integrity of the samples, did not introduce new materials, and they reacted concurrently with the sample when this suffered any changes. This provided a valuable guide when attempting to digitally register the image sets, the holes functioning as detectable features found in both the source and the target image.

These examples show how simple, creative solutions and experimentation aided the development of our approach by borrowing from conservation bench-work experience, simple devices, and advice from an online enthusiast community.

#### *4.2 Data acquisition*

This project acted as a pilot which led subsequently to the development of the Multispectral facilities in the UCL Centre for Digital Humanities Multimodal Imaging Suite.30 However, even this pilot study required access to specialist multispectral imaging hardware.31 Due to budgetary constraints, we had to assemble a working multispectral imaging suite with minimum expenditure.32 Having the right set of skills and expertise in the team—between colour science, and data processing and manipulation— made it possible to devise a low-cost, working multispectral imaging system.

The imaging setup was composed of two cameras: a Nikon D200 digital SLR camera with Nikon 105mm f/2.8 lens in combination with 16 Unaxis Optics bandpass filters; and a Kodak Megaplus 1.6i scientific monochrome camera with Nikon 50mm f/2 lens, using 5 Andover Corporation infrared bandpass filters in addition to the previous 16 (Figure 8).

The 16 Unaxis Optics filters each had a bandwidth of about 20 nm, and were centred at regular intervals of 20 nm from 400 nm to 700 nm. The five infrared filters had a bandwidth of approximately 50 nm, centred at intervals of 50 nm in the near-infrared spectrum, from 750 nm to 950 nm. During initial testing, it was discovered that the four filters above 640 nm in the visible spectrum also transmitted near-infrared light; with these filters, a second infrared blocking filter was used in combination. The five infrared filters were used only with the monochrome camera, as its sensor was sensitive to ranges from approximately 400 nm to 1,000 nm; the Nikon D200 had a built-in infrared blocking filter, and it was thus not capable of capturing images above 700 nm.

The system used two illumination techniques: standard document copystand lighting, and a lightbox backlight. The copystand illuminated the document using four tungsten-halogen lamps set at 45° angles (Figure 9); these lamps provided broadband emission from the ultraviolet into the near infrared. The lightbox backlight was made of two fluorescent lamps behind a flat diffuser, creating a uniform flat source of white light; these lamps illuminated mainly in the visible spectrum, and, for this reason, backlighting was only used with the colour camera. Transmissive lighting allowed illuminating the parchment samples from behind, thus interacting with both the surface, and the structure of the parchment.

**Figure 9:** Imaging setup. The camera is locked facing vertically downwards. Four tungsten-halogen lamps illuminate the sample at an angle of 45°. The sample is placed on the copystand over a piece of black card under a sheet of anti-reflective glass (Giacometti 2013).

In total, approximately 3,000 images of samples were acquired during the project in two imaging sessions: before, and after parchment degradation. The data from our experiments forms a set of multispectral images showing both the initial and degraded state of a manuscript. With a *do-it-yourself* attitude towards the equipment, creativity when dealing with problems, and high collaboration with experts in various fields, this project managed to create a large dataset of reference multispectral images of parchment damage within a relatively limited budget. We believe that these can become a valuable resource for both conservation research and libraries and archives undergoing digitisation efforts.33

## **5 Conclusions**

Multispectral imaging is increasingly becoming a common tool in cultural heritage, and it is therefore important to understand its applicability to the capture and analysis of our varied written heritage. Our research provides a systematic methodology to evaluate and review the techniques and processing of multispectral images of historical documents, thus allowing a most efficient use of resources.

In our research, we purposefully degraded a real historical manuscript on parchment, which was a necessary step to model successfully the type of damage commonly seen in historical documents. This helped us to understand how different types of damage affect historical documents and their text, both before and after multispectral imaging of the samples. The critical destruction was a fundamental part of the project, since it was essential to the understanding of the effectiveness of multispectral imaging on historical documents.34

Often, academic groups experience echo chambers, since their members tend to share information, *modi operandi*, and opinions. This situation is to some extent less critical within the digital humanities—an interdisciplinary field by definition—but looking outside the natural echo chamber for collaborations and knowledge exchanges can prove fruitful and leads to successful projects,35 as it was the case for the examples outlined in this chapter.

The knowledge exchange for this project was not unidirectional. Gathering information from adjoining fields certainly allowed us to design the phases and components of the project efficiently, however, the results and the analysis are beneficial to fields other than multispectral imaging of deteriorated parchment documents. To conservators and other professionals involved in the preservation of documents, for example, it is helpful to think about how to categorise damage according to what kind of analysis can or needs to be performed on a document to retrieve information (both written information and relative to its state of conservation) as, considering the usually limited resources of these groups of professionals, this would save time and costs.

*De facto*, by being open about the limited resources we had at our disposal, and the *do-it-yourself* spirit of our materials, equipment, and procedures, we want to highlight how interdisciplinarity and collaboration played a key and fundamental role for the success of our project. We also want to allow replication of our experiments and foster subsequent research and scholarship in the field. We envisage, in fact, that the dataset generated during the project has the potential to become an invaluable asset for libraries and archives, research in conservation, and various image and signal processing sets of problems, and have made all of the data generated from this project freely available online. Our dataset36 provides physical information of how parchment reacts to various forms of degradation, but also provides consistent process and documentation on acquisition, and will provide a test environment for any future research whilst reducing the need for experimentation on valuable primary historical texts.

# **Notes**

#### **References**

April 2013. Presented at the Icon PF13, Positive Futures in an Uncertain World, Glasgow, 10–12 April 2013, Glasgow.

Visualisation and the Arts (EVA 2012), British Computing Society, London, UK, pp. 301–308.

# CHAPTER 8

# **Transparent, Multivocal, Crossdisciplinary: The Use of Linked Open Data and a Community-developed RDF Ontology to Document and Enrich 3D Visualisation for Cultural Heritage**

Valeria Vitale

King's College London

#### **Abstract**

Scholarly 3D visualisations of cultural heritage are based on a thorough study of excavation records, iconographic documentation, literary sources, artistic canons and precedents. However, the research process is usually not detectable in the final visual outcome, thus bypassing a fundamental principle of scientific method: the reproducibility of the process.

International guidelines define the kinds of information essential to making a 3D visualization an academic resource, but without specifying a technological format or standard for doing so. This chapter proposes the use of Linked Open Data and a dedicated ontology as a synthetic, time- and costeffective way to document 3D visualisation, connecting the 3D model and its parts, both internally with each other and externally with online information about material remains, as a standard for the community of practitioners involved in the study, preservation and communication of cultural heritage. This semantic network could be implemented, in the number of its elements

#### **How to cite this book chapter:**

Vitale, V. 2016. Transparent, Multivocal, Cross-disciplinary: The Use of Linked Open Data and a Community-developed RDF Ontology to Document and Enrich 3D Visualisation for Cultural Heritage. In: Bodard, G & Romanello, M (eds.) *Digital Classics Outside the Echo-Chamber: Teaching, Knowledge Exchange & Public Engagement*, Pp. 147–168. London: Ubiquity Press. DOI: http://dx.doi.org/10.5334/ bat.i. License: CC-BY 4.0.

and connections, by different communities sharing the same controlled vocabulary, potentially reaching a richness and complexity of information that no single author, discipline or industry could ever achieve.

This chapter suggests how a community-developed ontology will help creating an inter- and multi-disciplinary network of documented 3D data, moving 3D visualisation from a univocal 'snapshot' of the past to a collaborative virtual laboratory where different voices and different interpretations can be hosted and compared.

#### **1 Opacity and Transparency**

'3D visualisation' is a broad term used to define computer generated threedimensional representations of objects (concrete or abstract). In its application for cultural heritage, it is often divided into '3D modelling,' which involves the use of Computer Aided Design (CAD) software and the creation of 3D content from scratch, and '3D imaging,' which involves the digital recording of information on the shape and colour of existing objects. The division between these two main streams is in no way neat, and there are several intermediate approaches that blend different techniques.

On the one hand, the use of 3D technologies seems to be increasingly common in the study, preservation and communication of cultural heritage and, in particular, of the ancient one. A survey of panel discussions at conferences such as Computer Applications and Quantitative Methods for Archaeology (CAA)1 or Digital Heritage2 in the past years, and a look at the online content offered by museums,3 point out a growing interest towards 3D data. The increasing affordability of 3D technologies and the usability of their interfaces, combined with the recent booming of 3D printing,4 have made digital platforms to upload, share and download 3D content rather popular among expert and non-expert audiences.5 On the other hand, 3D visualisation is still not fully integrated in the academic workflow, and it is often considered more an illustration of external research than an investigation tool of its own.6

Although it is easy to understand the caution of the academics using 3D tools in their research,7 the diffidence towards these digital outputs cannot be simply dismissed as resistance to change and technophobia.

One major issue is that, in the vast majority of cases, 3D visualisations are completely 'opaque': it is nearly impossible for the public, or for the academic community, to assess the accuracy of the visual outcome or the soundness of the hypotheses represented. The research around the visualisation, its sources, evidence and references, remain almost entirely hidden, as well as other pieces of information crucial in academic publications such as the date of publication or, sometimes, even the name of the authors.

Generally speaking, opaque digital products are still used in a large number of museums as, traditionally, they tend to present the audience with one single view of the artefact displayed, and seldom share any information on the construction of that particular interpretation, or acknowledge the possible existence of others.8 In these contexts, 3D visualisations are often used as communication (if not entertainment) tool, meant more to appeal the public for their technological and/or aesthetic value than to actually add anything to the knowledge or investigation of the artefacts represented.9 Even the Museo Archeologico Virtuale (MAV) in Herculaneum, which is proudly and boldly developed around the idea of having no material artefacts but only information about them and digital reproductions, offers opaque 3D content.10

Not knowing enough about the process of building both the 3D visualisation and its interpretation, the public's only choice is to trust the authority of the cultural institution. Although still quite common among museums and cultural heritage sites, this use of multimedia and digital tools has been criticised as it promotes a univocal, authoritative and flat approach to cultural heritage that diminishes its richness, and discourage engagement.11 Furthermore, when the cultural institutions rely on their prestige to guarantee the quality and accuracy of the 3D visualisation, they reinforce the misconception that the one proposed is the only possible or the only correct 3D image.12 This issue, which was already evident in the critique of illustrations for museums and historical publications,13 seems to have been entirely perpetrated in the digital, threedimensional medium.

Although some cultural institutions find convenient to promote their digital content as 'perfect reconstructions' or 'perfect copies'14 of artefacts, such a statement is not only untrue but also misleading. First, 3D visualisations are digital representations of objects and, as such, they only display some aspects of their referent. They are, in fact, a '*representation of something for purposes of study*'.15 Second, 3D modelling and even 3D imaging are based on a continuous process of decision making and subjective interpretation of the (often incomplete) available information.16 This would already be true in the visualisation of a still standing artefact, but it is even more apparent when developing hypotheses on the look of no more existing or heavily damaged ones. Last, as an interpretation, every visualisation is subjective in the same way a photograph is. If the idea that photographs always express the point of view of the photographer and not an objective reality17 is now commonly accepted, the same assumption is curiously ignored (even by practitioners18) in the case of 3D visualisations, and especially 3D imaging.

If an opaque and univocal digital visual product seems to be (arguably) considered acceptable in a commercial environment, it definitely cannot pass the threshold of academic publications, and cannot join the scholarly debate, regardless the rigour of the research and the value of the hypotheses behind it. With most part of the informative value hidden, 3D visualisations are as useless in academia as would be a paper missing the authors' names, methodological discourse, bibliography and footnotes. Insufficient documentation makes the process not repeatable and, thus, not complying with the scientific standards.

# **2 The London Charter: its Applications and Limits**

The scarcity of exhaustive documentation for academic 3D visualisations can be attributed to several different causes. According to Goodrick and Earl (2004), the initial enthusiasm for the technology has driven the application of 3D tools to academic research more than a methodological reflection on it. Also, disseminating the documentation opens more than few technical issues that span from the publication of the 3D content per se (only recently made dramatically simpler) to strategies to correlate text and images to 3D environments. Last, being the commissioners of 3D visualisations of cultural heritage usually only interested in the final visual product, researchers often have to argue (and not always successfully) for the documentation to be included in the project's budget.

All these issues involving authorship, peer review, digital publishing technologies, preservation strategies and their implications in the development of 3D visualisation as a scholarly tool were already a concern of the first pioneers in the field.19 The interest in a proper scientific methodology for scholarly 3D visualisation led to the publication of the London Charter20 (2006): a set of guidelines for the use of 3D technologies for cultural heritage. The Charter makes some excellent points, among which:

*Sufficient information should be documented and disseminated to allow computer-based visualisation methods and outcomes to be understood and evaluated in relation to the contexts and purposes for which they are deployed.* (The London Charter. Principle 4: Documentation)21

However, ten years after the publication of those guidelines, the number of documented 3D visualisations is surprisingly very low, even within academic projects.

There are, of course, examples of approaches to documentation of scholarly 3D visualisation. One is the work on the Villa of Livia at Prima Porta.22 The 3D component, in the form of an explorable environment with narrative elements, was distributed on a CD-ROM alongside a traditional printed publication covering the archaeological research on the material evidence, plus some chapters about the specific challenges of the 3D representation. Although this approach may sound safe as it follows more traditional scholarly conventions, it does not unfold the correlation between the look of the 3D model and the archaeological research, but presents the two outcomes separately, often asking the viewer to believe that the model is nothing else than the natural outcome of the discussed archaeological finds. Again, the viewer has to trust the competence of the virtual archaeologists, and cannot really challenge specific aspects of the 3D model, or know on what other sources, not published in the book, the researchers have relied.23

Another strategy to document 3D visualisation that seemed affordable and easy to use in the past years was the use of blogs, like, for example, in the case of the 3D visualisation of the Abbey Theatre in Dublin at the time of its inauguration in 1904.24 However, the information provided remains quite generic, and when looking for the resource related to a specific part of the model, the user has to read the entire documentation in order to find any particular piece of information, if available. Other projects, such as Digital Pompeii,25 use some of the digital 3D models to browse and access, on click, the images, hosted in an internal archive, that are related to the specific element selected, showing past or contemporary pictures of the actual remains. Although this seems to be an informative and interactive way to access archaeological resources while offering, at the same time, some documentation about the 3D environment, the system can only deliver information when the source is part of that single digital repository.

A more rigorous approach is the one followed by University of California Los Angeles (UCLA) researchers and showed, for example, in projects like the Digital Roman Forum26 or Digital Karnak.27 In both cases, some of the main components of the buildings modelled are discussed on the project's online platform and connected with visual or verbal sources and with bibliographical references. Although very promising, the methodology does not seem to be followed systematically for all the buildings' components, and the provenance of information remains often not declared.

Although incomplete and partly flawed, all these attempts can be seen as steps forward towards a more scientific use of 3D visualisation. Besides their differences, they share some common issues in the process of documentation. None of the mentioned cases, for example, records what happens when the researcher has no direct information about a given element. Likewise, no-one mentions alternative and conflicting sources and how the author has dealt with them. None of them mentions alternative hypotheses or interpretations.

What this very brief review wants to highlight is, mainly, the range of variety and degrees of accessibility in the existing approaches, and how their different formats, structures and criteria make the documentation hardly comparable and searchable. The lack of a standard and a consolidated workflow contributes to make documentation a confusing and time-consuming process. Last, 3D visualisations, especially extensive and complex ones, are usually the work of more than one person.28 The number of authors, often with different skills and interests, makes it even more difficult to follow a single, well-defined standard.

This overview of the difficulties in documenting 3D visualisations for cultural heritage stresses that, after agreeing on the need of documentation, it is also necessary to define a documentation standard that makes the process time and cost effective, and allows comparisons. Here, we want to suggest that the use of Linked Open Data (LOD) technology29 and the creation of a dedicated resource description framework (RDF) ontology can be an effective approach to documentation, and also open new possibilities that were not foreseen in the London Charter, including a more multivocal approach to the representation of cultural heritage, and a process of knowledge exchange with non-academic partners such as cultural tourism, museum management, urban planning and education.

# **3 Why Linked Data?**

LOD is an existing technology that has already been tested, and has proven its usefulness in successful digital projects on the ancient world such as the Pleiades30 gazetteer of ancient places, Pelagios31 or the Perseus Digital Library.32 It is a low cost technology producing lightweight outputs that create less concern than average about their preservation. It is easy to learn and use even for people that are not particularly familiar with digital technology.

LOD establishes connections between data through statements (roughly) in the form of subject-predicate-object. These statements are expressed using controlled vocabularies.33 Thus, the nature of LOD makes it quite suitable to be applied as a standard to describe a 3D visualisation and its production, implicitly acting as a constraint, and making, eventually, documentation comparable and not idiosyncratic.

The use of LOD allows us to attach specific information to each element of the 3D visualisation and to annotate it. Moreover, being open and nonhierarchically structured, a documentation expressed in LOD will allow multiple authors to annotate and add information about the same entity, encouraging the idea that a 3D visualisation is the representation of only one of the many possible hypotheses and interpretations. Last, LOD is both human and machine readable. It means that it can be read as comprehensible synthetic documentation for a 3D output, but also that, once online, the information can be harvested by APIs, and connections automatically identified and showed to the users.

Linked data is becoming a fairly popular technology and its applications are widely investigated in many different disciplines. There is in fact a growing number of ontologies34 meant to describe specific domains or processes. Museums are one of the fields that show a strong interest in linked data35 and are the cradle of one of the most widely known and applied ontology, the CIDOC CRM.36 Looking at museum ontologies seemed the first natural step in sketching a language to document cultural heritage. However, an attempt to use the existing ontologies, even in combination, to document a 3D visualisation, pointed out some crucial gaps, and suggested the necessity to draft a purposespecific new ontology. In the first place, the museum ontologies tend to focus on the material artefacts and not on their digital representation. In general, none of the existing ontologies offers a vocabulary that describes the specific process of producing a 3D model or image of an existing or destroyed artefact on the grounds of academic research.37

Writing a new ontology, even a basic one, is not to be considered a task for a single researcher for both practical and methodological reasons. Form the practical point of view, the amount of work does not seem likely to be undertaken by a single person in the time of an average academic project. Even more important though is the methodological objection: 3D visualisation is a very wide and diverse field that includes under its umbrella a large number of approaches and techniques, from Computer Aided Design (CAD) models, to laser scanning, to the use of footage produced by drones. Writing an ontology that describes a production process requires a deep understanding of the process itself and of the real issues met in the attempt of recording it consistently and synthetically. Moreover, writing an ontology is a knowledge representation process, i.e. it models a view of the world. An ontology modelled on the assumptions, expertise and needs of a single researcher would be of limited use for the rest of the community. For all these reasons, the suggested purpose-specific ontology, named SCOTCH (Semantic Collaborative Ontology for Three-dimensional visualisation of Cultural Heritage), is meant to be intrinsically collaborative, and requires that different communities of practitioners engage with its refinement and implementation, according to their own specific point of view. However, as a proof of concept, the author has started drafting a first subset of the ontology that, according to her direct knowledge and use of 3D visualisation, focuses on documenting the process of 3D modelling ancient buildings.

#### **4 The SCOTCH Ontology**

Expressing documentation in LOD requires that the 3D file is divided into smaller units first, each of them receiving a specific Unique Resource Identifier (URI). It is, obviously, possible to connect all the information to the single main file (and to one single URI), but that would diminish the effectiveness and specificity of the documentation, and make less easy the debate around a given element of the visualisation. Dividing a 3D representation of an object (in this specific case of a building), though, is not a straightforward task. A model developed with a CAD software generally allows to identify and isolate different elements up to the level of the single vertex.38 It is not possible to define a level of granularity that suits all the cases, as different researches focus on different aspects (and scale) of cultural heritage, from urban landscape to microscopic analysis of the single artefact. LOD allows the addition of both further specifications and further generalisation without affecting the pre-existing data, facilitating, for example, the practice of building on top of previous research zooming in or out its original scope.

When visualising ancient heritage, and in particular architecture, it may appear a natural decision to rely on the many and very detailed available taxonomies.39 However, using semantically charged labels would make the 3D visualisation fall again into that univocality that we were trying to avoid, or at least minimise. Calling a building 'temple' or a space 'kitchen' is already a (subjective) interpretation and could be challenged by other scholars, especially when describing ancient buildings and settlements where so much information is missing.40 The SCOTCH ontology aims at dividing and naming the space in the most neutral way possible. Labels about the name or the function of a given element will then be linked to it, each connection expressing the statement of a specific author and, possibly, a bibliographical reference. Obviously, more than one label could be attached to the same element.

After naming the parts of the 3D visualisation in a consistent way41 and assigning each a URI, the primary purpose of SCOTCH is to make visible the connection between each element and the related sources and documents. In this respect, the present research does not intend to create redundancy with existing ontologies that already successfully model both explicit and implicit citations, such as the Citation Typing Ontology (CiTO),42 but to fill the gaps related to the specific domain of 3D visualisation, and to create a conceptual framework that maps and harmonises the useful parts of various available ontologies, especially when they are already well received by part of the academic community.

Looking at other digital projects, including LOD based ones, the most common way to express relationships with the sources, especially when they tend to be fuzzy, is through a degree of certainty.43 Nonetheless, SCOTCH prefers to avoid the use of the word, and in general the concept of, 'certainty'. First, rating the certainty of a source may suggest a quantitative approach to documentation that is not in the SCOTCH agenda. 'Certainty' is an ambiguous concept and can be perceived differently by different researchers. There are no guidelines or shared conventions on what it takes for a source to be labelled as 'certain'. It is not clear if, for example, primary sources should be considered more or less certain than secondary ones, or what would happen if there are inconsistencies between them. Is the source rated with the highest level of certainty always the most accurate? In addition, in the specific case of archaeology, information is often a work in progress, and new evidence can always arise and contradict or complement the previous one. These characteristics make a quantitative assessment of the sources of limited use and problematic application. But, above all, simply communicating the degree of certainty about a visual hypothesis does not actually contribute to making it more transparent. The use of values of certainty may also suggest that there is a degree of preferability among types of sources. SCOTCH advocates that not only all sources can be debatable in their own respect, but also, and mainly, that it is beyond the scope (or the interest) of this ontology to assess the 'quality' of the sources. SCOTCH simply aims at showing the methodological relationship between an element in the 3D visualisation and the information that motivated the visual output.

Instead of degrees of certainty, SCOTCH prefers to refer to types of sources, indicating, for example, if a given element is based on direct observation of still standing artefacts or on secondary historical sources; if it is deduced from material clues or imagined according to external references; if it is based on the expert knowledge or even intuition of the researcher and so on. As there are many possible purposes for the visualisations (including purely recreational ones), there are no types of sources that are discredited *a priori,* as long as their use is clearly documented. Those elements that appear in the 3D visualisation only to add contextualization value,44 when not mere 'colour,' are very likely to lack any actual historical evidence, but they can be nonetheless useful in particular research outputs. All types of sources can be part of a documentation when it becomes clear that the 3D visualisation does not aim at representing the material artefact, but the knowledge of the author about the artefact. In this view, showing a lack of historical sources can be as informative as communicating which are the sources that have actually been analysed and investigated. As mentioned, the main aim of SCOTCH is, basically, to point out at the source of information (in the form of link to online digital resource, bibliographical information or annotation). However, also stating the type of the source (choosing from a controlled vocabulary of available choices) appears as a useful option that will allow us, for example, to render the 3D visualisation highlighting or hiding the elements that are based on a particular type of sources.45

Each of the subsets of SCOTCH will cover and model, through the ontology, specific issues related to the technology of choice or the field of application, from the research process to the simplifications, normalisations and post-editorial choices. However, for the purpose of this paper, it is no use to discuss them in depth46 and it seems more appropriate to remain on a methodological level, stressing that, basically, the application of LOD and the development of a dedicated semantic ontology will allow us to attach information of different kinds to specific parts of the 3D output, and to introduce 3D into the growing pool of data about cultural heritage that is already published online in LOD format.47 This approach allows different authors and different datasets to dialogue in spite of their differences, as long as they refer to the same element (identified via a URI) and the same vocabulary (the ontology that is community developed).

### **5 What would be the Benefits?**

The first major benefit in the use of LOD to document 3D visualisation will be, obviously, the enhanced transparency of the 3D output. It will also open the door to aspects of the academic research from which 3D visualisations are currently excluded such as repeatability of the process (because other researchers will access detailed information about sources analysed and methodology followed), peer review (because the quality of the hypotheses represented and the provenance of the sources will be assessed) and citation (because information about authorship will be attached to the single 3D element). Furthermore, it will force researchers to reflect critically on their sources, on their choices and on their methodology.

#### *5.1 Within Academia*

The use of LOD, and a dedicated ontology, will affect scholarly 3D visualisation both from the inside (in the way it is carried out and disseminated) and the outside (in the way it is received). The opportunity to attach information (as annotation, bibliographical references, alternative sources and hypotheses) will not only open a discussion between different researchers in the same discipline like two archaeologists comparing their research on the same artefact—but it will turn the 3D visualisation into a multidisciplinary portal where scholars from various discipline can link information and add annotations that are relevant to their own research. As a consequence, on the one hand the 3D visualisation will be an open-ended aggregator of multidisciplinary information on the same object, on the other, the 3D visualisation will see its informative value dramatically increased thanks to the different perspectives and variety of sources connected. Even when not interested in the 3D visualisation per se, members of the scholarly community may want to use it as a digital, searchable portal of information on a given artefact. The 3D visualisation of a Roman temple, for example, could gather information, expressed in linked data, from archaeologists interested in the material remains as well as from art historians interested in the wall paintings. The subject depicted could be linked to taxonomies of art techniques and/or proposopography of mythological characters, and so on. The examples could be countless and varied, potentially involving any discipline from anthropology to engineering.

#### *5.2 Outside Academia: Knowledge Exchange*

The availability of a documentation for 3D visualisation, its openness and multivocality potentially lead to a wider use of the visual outputs outside academia, consolidating mutually beneficial relationships with members of the private sector. To mention a few examples of possible exchange:

#### *Museums and Archives*

As discussed, 3D visualisations displayed in museums do not seem to be successful in engaging the audience because the information delivered, despite the technological novelty, is often still mono-dimensional and authoritative.48

Making the documentation available to the public (along with the opportunity to filter the information according to competence and interest) can change this attitude, and contribute in enhancing the audience experience in museums. First, allowing the public to see the 'behind the scene' process of research around the artefact and its visualisation will include them in the process of meaningbuilding, as advocated in the constructivist approach.49 Second, showing the existence of conflictual and incomplete information and the existence of open ended questions is likely to solicit curiosity in the visitors and stimulate a more critical thinking.50, The opportunity to evaluate how much of a 3D visualisation for cultural heritage is actually based on speculation will stress the fact that many hypotheses are possible, even starting from the exact same evidence and sources. In the most optimistic view, an open and interactive documentation can encourage the public to add their own annotations to the 3D visualisation. Then, it is each institution's decision how to manage the access to their data and to what extent allow users to add information. Different models can be adopted from open-to-all access to more or less strict moderation, involving editorial boards or the most suitable vetting process.

Likewise, all the other examples of knowledge exchange, the benefits will be bidirectional. On the one hand, disseminating more engaging 3D products for cultural heritage will make them more popular among cultural institutions, reinvigorating the use of 3D visualisation in academic research and reinforcing the idea that documentation is actually a crucial and necessary component of the final output, even in commercial contexts. On the other hand, the annotations from the public carry a considerable informative value of their own when considered as both subject and object. They enrich the 3D visualisation in the number and variety of connections expressed, can identify new sources, point out inconsistencies and propose new alternatives. Also, members of the public can be the last witness of lost information about cultural heritage in the form or family archives and personal memories. But, besides this, the annotations from the public are a corpus of data in its own right that could be subsequently analysed in other researches investigating, for example, reception of cultural heritage. Although this scenario appears like a step forward towards the representation of more voices in the study and communication of cultural heritage, it remains clear that it is by no means a solutions to the issue of underrepresented minorities, and, at the moment, the technology is still likely to be used almost exclusively by a specific segment of population.51

Another line of collaboration between academic 3D visualisation and museums goes through 3D printing. The printed replica, of course, only reproduces some aspects of the original artefact. Nonetheless, the manipulation of facsimile seems to be a promising strategy in enhancing the understanding of the artefact and to make it partially accessible to the visually impaired. Some museums are already sharing with the general public 3D scans of their artefacts that can be easily 3D printed.52 Making available not only the 3D files but also their documentation, museums can offer a much bigger value than just a file to download at home. Also, if properly documented with information about authorship, copyright and a description of the sources, external 3D files can be used by smaller museums (that cannot afford their own digitisation program) in order to engage the public.

The potential exchange with museums does not only involve directly the general public. 3D visualisations documented in LOD will help museums' and archives' catalogues to interlink meaningfully their resources (sometimes already in linked data format) according to different criteria, from commonality of provenance to subject depicted. Making these relationships visible will create a straightforward digital unification, even just at an informative level. Also, highlighting connections between different collections and archives may suggest new discoveries that would have not been possible when looking at only one repository. The web of connections around the 3D visualisation will also work as a possible starting point for museum exhibitions (in the traditional physical form or in an entire virtual space). Lastly, it will help pointing out gaps and inaccuracies in the museums and archives' own documentation, generating, when possible, more correct and reliable information.53

#### *Teaching and Education*

The application of LOD to 3D scholarly visualisations will make them part of the new family of digital tools and strategies used in educational environments to teach students about the ancient world while using their inputs to populate databases and annotate texts and images. For example, when a building or artefact is mentioned in an ancient text, or reproduced in an archive document, students involved in theses digital programs will be invited to include 3D visualisations in their annotations, making the amount of information connected to the 3D files vaster and deeper than the one any single group of researchers could ever achieve.

From a pedagogical point of view, the exercise of connecting historical documents (from digitised ancient text to excavation reports, journal entries and historical depictions) will promote among the students the idea that all representations of cultural heritage are subjective and culturally biased. Moreover, the act of establishing connections between the same source and more than one 3D visualisation will show how everything we know about the past (and the way we represent it) is always incomplete and hypothetical.

#### *Artefacts and Building Restoration*

Documented 3D visualisations can be a valuable tool for curators and restorers to monitor changes and degradation of artefacts and buildings, displaying accurately to what part of the object the measurements, reports and analysis refer. Even when the scientific information will not be fully available to the public for copyright issues, it could be linked as bibliographical reference, facilitating dialogue and contacts between different laboratories and professionals. A comparison between measurements of the same object, taken at different times or with different equipment, can also help identifying biases and problems that are due to technologies more than methodology. The various connections to other artefacts showed through the documentation and annotations can lead restorers to the identifications of useful precedents or similarities and, as a consequence, to the development of new restoration hypotheses.

#### *Geography and Urban Planning*

Laser scanning the archaeological digs to record different stages of the excavation process is presented by virtual archaeologists as a more effective means to document the excavation, compared to traditional bidimensional representations.54 According to Dell'Unto (2014), 3D images offer a better and more detailed record of the archaeological site as it was before and during the intrinsically destructive process of excavation. Especially when combined with haptic technologies or oculus rift, a 3D imaging of the site, theoretically, allows to re-examine the excavation later on, even when the actual place and the archaeological evidence do not exist anymore.

An annotated 3D digital record of the landscape and the terrain stratigraphy can prove extremely interesting for geological and hydrological surveys. It will maximise the usefulness of the archaeological investigation, producing data that are, potentially, accessible by various industries. The opportunity to link together, to the same 3D visualisation, both academic and commercial reports will produce a very rich and unprecedented pool of information. Commercial companies may analyse the 3D scanning of archaeological excavations (and the related and connected reports) in order to avoid or reduce preliminary investigations in the same area, and archaeologist could have their study of the terrain enriched by the annotations of other professionals that will use different approaches and, probably, different technologies. In a few years, the availability of these kind of 3D records might become a crucial source of information in understanding the changes in the area, and how human or natural activities have influenced the environment. Likewise, annotated 3D scanning of underground areas of a city (such as those recently performed in Rome55 or London56) could be shared with the local municipality and contribute to a more efficient planning of urban works like, for example, the improvement of the underground transportation system.

What the examples above want to point out is that the availability of 3D data as such is not likely to have a significant impact as long as the information remains opaque and univocal. But, as soon as it is documented, and, even better, it is documented in an open, multivocal and multidisciplinary way, then its usefulness increase dramatically and can be potentially of interest of many different public and commercial fields, not necessarily immediately related to the cultural heritage sector.

### *5.3 Engaging the Academic Community*

Although the focus of this paper is on the impact of scholarly research outside academia, it seems appropriate to conclude this overview started with public engagement and multidisciplinarity, with few words on the engagement of scholars within academia. A virtual transparent 3D environment that links and discuss information from different fields and perspectives, can be a promising premise to a cross-disciplinary dialogue. The collaborative nature of the semantic ontology is not only a necessity driven by the variety and complexity of the matter, it is also a means to engage the academic community on the shaping of the knowledge representation process and to make the documentation standard as widely known and familiar as possible. Every project involving 3D visualisation, in this view, is never finished, but always open to new sources, to new debates, to new variants and hypotheses.

# **6 Potential Issues**

The documentation of 3D visualisations for cultural heritage in LOD format is still at an experimental stage, and there is not enough evidence available yet to predict its success or foresee its limits. Furthermore, this application is based on some assumptions that have not been proven.

#### *6.1 Who is the author?*

The first one is that 3D visualisations of cultural heritage are developed by the same person(s) that are in charge of the historical or archaeological research. Such professional figures do exist in academia and belong to a well-established trend in the Digital Humanities (and especially Digital Classics). There are several cases in which, for example, 3D visualisations of ancient places and artefacts are used to teach, at the same time, 3D techniques and Classics.57 However, there is an opposite trend that sees the 'humanists' undertaking the academic research, and then 3D 'technicians' making the humanists' research visible producing the 3D output.58 In this case, it is easy to imagine how the process of documentation, and the whole attribution of authorship and intellectual ownership, becomes more complicated.

#### *6.2 Are contributors willing to share information?*

The second assumption is that all potential contributors, inside and outside academia, are willing to share the outcome of their work. It is a fact that the amount of data available on line (sometimes already in linked data format) is constantly growing, but, of course, many things still have restricted access. The issue could be theoretically overcome considering that links can be established with documents and pieces of information that are not actually online, but that can be identified through their metadata or URIs. Following the example of platforms like Recogito,59 the LOD documentation only aims at connecting information, without duplicating, or publishing the documents. Nonetheless, copyright issues and a certain reluctance among private companies is not unlikely to manifest.

#### *6.3 Are researchers willing to be assessed?*

Another concern seems to be that many researchers using 3D technologies have been quite comfortably hiding behind the screen of opacity and actually do not want each and every one of their intellectual choices to be scrutinised by the entire community; including all those implicit simplifications and regularisations that are part of the visualisation process, and that are almost automatic to 3D practitioners. It is not unlikely that virtual archaeologists (and other researchers using 3D technologies) are, even at an unconscious level, reluctant to the idea of stating on how many occasions they work without referring to any specific source but relying on their experience and intuition, feeling that such an admission will undermine their entire research. It is important to change the expectations in the expert and non-expert audiences about 3D visualisations and stop promising 'perfect replicas' of things from the past. More realistically, and more interestingly, scholarly 3D visualisation should be presented as the expression of a researcher's point of view on an ancient artefact, with all their biases and gaps, but open to discussion, confrontation and implementation.

#### *6.4 Is the community interested in expanding the ontology?*

The last major assumption is that the community of users is willing to be engaged in the development and refinement of the various subsets of the SCOTCH ontology. It will require the organisation of testing and discussion groups, and the sharing of the first results of the application of the ontology to the different sub-fields of 3D visualisation. Also, the process of decision making to judge if a new term should be introduced in the ontology, or if changes have to be applied needs to be completely set up. Even if based on the voluntary contribution of the users, a community built ontology will require a considerable investment in terms of time and resources.

#### *6.5 What is the most appropriate technology?*

At this stage, SCOTCH is mainly a conceptual framework that aims at harmonising elements from pre-existing ontologies and new ones created ad hoc to describe the specific process of producing a scholarly accurate 3D visualisation, identifying methodological similarities in the workflows of different 3D techniques. More than a ready-to-use application, it is an attempt of modelling, among other issues, the complex and multifaceted relationship between cultural heritage, the present and past research about it, and its digital, threedimensional representations.

Effective ways to connect the linked data to the single 3D elements, and to display, meaningfully and clearly informative relationships and/or the outcome of a query, have to be further investigated and tested. The use of a cross-platform application programming interface (API) such as OpenGL60 seems, so far, the most likely direction to go, but the question remains open. Moreover, a suitable user interface, able to present together the 3D visualisation and the LOD based information related to each element, still has to be designed. Useful lessons can be learned looking at the interfaces of other, successful LOD projects, but the intrinsic stress on visual information is likely to require specific features to be designed and discussed. A potential involvement of public and private IT companies at the stage of 3D software development, in order to include a user friendly documentation tool may prove a promising collaboration.

#### **7 Conclusions**

This research was mainly driven by the necessity to constrain and standardise the documentation of 3D visualisations, making it time and cost effective, and thus more likely to be retained in a project's budget. However, we believe that the application of LOD technology and a dedicated ontology to 3D visualisations also presents a number of other potential benefits. In general, it will allow documented 3D visualisations to join and enrich the growing network of linked digital resources on cultural heritage, making 3D visualisations human and machine searchable, connecting them with contemporary and historical sources. It will also encourage comparison of different visualisations and interpretations of cultural heritage, as the same resource will be connected to all the related visualisations that share the same vocabulary. Likewise, it will facilitate citations, re-use and peer-review of 3D visualisations, as every 3D element (and its author) will be always identifiable and linkable through the URI.

We see the value of SCOTCH especially as a means to change the ways 3D visualisations of cultural heritage are perceived and experienced by both expert and non-expert audiences; to move from a univocal display of traditional research to a collaborative virtual environment that can be shared and implemented by different authors.61 We envision SCOTCH, and the research around it, as a step towards a shift in perspective: from the static representation of a material artefact to the dynamic and open-ended representation of the knowledge around that artefact.

With the caution due to the involvement of many and different actors in the process of creating a 3D visualisations, and the various degree of openness that are convenient to each partner, this approach seems to facilitate a large number of fertile and mutually beneficially interactions between different disciplines within academia, between public and private sectors and between authors and consumers of 3D visualisations.

Several theoretical and practical issues remain open to discussion and improvement, from the management and coordination of the collaborative effort to the need of a shared and well established naming conventions for the component parts of 3D visualisations. We see stimulating and channelling such a discussion and its outcomes, as one of the first and most profitable outcome of this research.

#### **Notes**

<sup>6</sup> Hermon 2008.

<http://dbpedia.org/ontology/> or the FRBR Term Summary at <http:// vocab.org/frbr/core.html>.

Articles/April-Volume-38-Number-2/ISSUES-IN-EDUCATION>, Education World <http://www.educationworld.com/a\_curr/responsiveclass room/responsiveclassroom014.shtml> or Canada Education <http:// www.cea-ace.ca/education-canada/article/engaging-students-througheffective-questions>.

# **References**

a Digital Epoch*.* In F. Cameron, & S. Kenderdine (Eds.)m *Theorizing Digital Cultural Heritage. A critical discourse.* Cambridge, MA: MIT Press.

# SECTION 3

# **Public Engagement**

# CHAPTER 9

# **The Perseids Platform: Scholarship for all!**

Bridget Almas\* and Marie-Claire Beaulieu†

\*Perseus Digital Library, † Tufts University

#### **Abstract**

It is rarely possible for students, members of the public, and other non-traditional scholars to access ancient documents such as texts, inscriptions, and manuscripts. The Perseids collaborative editing platform offers a gateway to scholarship which is open to all, regardless of native language, background, and level of expertise. Within this fully integrated online environment, participants can view, edit, translate, and annotate ancient documents (texts, manuscripts, inscriptions), while contributing to an ever-growing repository of open access humanities data sets. The variety of tasks available, which ranges from textual criticism to annotation of personal names and geographical entities, ensures the inclusion of all participants, and offers them a chance to learn and perform increasingly difficult tasks as they gain expertise. At the core of the platform is the integration of two pre-existing frameworks, the Son of Suda Online (SoSOL) and the CITE services. The former enables collaborative editing by providing workflow tools on top of a Git-based revision control system, supporting a built-in, versioned review process whereby each contribution is examined by a board and receives feedback before being approved for publication. The latter provides standards and APIs designed to link the resources, provide a citation scheme for texts and images, and support dynamic presentation of digital editions. Together, along with a variety of other integrated tools, standards, and services, these systems enable the Perseids platform to support communities of participants, who can collaborate based on participation in a class, shared interest in a literary work, or interest in a category of documents.

**How to cite this book chapter:**

Almas, B and Beaulieu, M-C. 2016. The Perseids Platform: Scholarship for all!. In: Bodard, G & Romanello, M (eds.) *Digital Classics Outside the Echo-Chamber: Teaching, Knowledge Exchange & Public Engagement*, Pp. 171–186. London: Ubiquity Press. DOI: http://dx.doi.org/10.5334/bat.j. License: CC-BY 4.0.

# **1 Introduction**

Current practice in Digital Humanities focuses heavily on crowdsourcing as a model for producing knowledge, vetting contributions, and in general, dealing with large datasets.1 In Classics, the rapid growth of digital repositories and the increasing number of largely unedited and untranslated documents available online for processing—thousands of Greek and Latin inscriptions, 900 medieval manuscripts from e-codices and 250 from the Walters Art Museum, to name only those few—practically force us to abandon traditional single-scholar approaches to adapt to the realities of the digital age.2 The needs are simple, yet challenging: we must process more documents, but we must do so in a manner that is sustainable, upholds the established standards of quality in the discipline, and will result in the production of fully interoperable, transferable data.

The advantages to the method are obvious: a well-organized crowdsourcing effort can accomplish far more work than any lone scholar and the work ultimately produced benefits from the variety of perspectives included in its user base. Furthermore, crowdsourcing helps break down the social and geographical barriers that have long kept ancient documents and scholarship in a limited number of hands. However, the pitfalls of crowdsourcing are numerous, such as ensuring the reliability and consistency of the data being produced and ensuring the longevity of projects by renewing and growing the user base.3 Finally, as crowdsourcing is more and more frequently practiced in classroom settings, questions arise with respect to pedagogy.4 Does crowdsourcing change traditional teaching methods in Classics, and if so, how? In this new disciplinary landscape, what is the relationship between teaching and scholarship?

The Perseids platform,5 nested within the Perseus Digital Library,6 offers an online collaborative editing and annotation environment in which to test different approaches to crowdsourcing and pedagogy. Users can form communities based on participation in a class, in a research project, or individual interest in a particular type of document or question. The flexibility of the platform and the variety of tools offered ensure that users at every level of expertise and from a variety of fields can undertake editing and annotation work. Such broad participation leads us to rethink the role that scholarship plays in pedagogy, and in general the role that Classical scholarship can play in engaging Perseids users with the past.

#### **2 The Audience of Classics Scholarship**

Classics scholarship, in the form of interpretative essays, critical editions, and other forms of highly specialized publications, has long been strictly targeted to established scholars such as university professors and other professionals in the field. The objective of such publications is generally understood to bring knowledge further by engaging specialists in a conversation among themselves. This is certainly useful: in all fields, it is important for new discoveries and new ideas to be examined carefully by those who know the most about the field and therefore can cast a critical eye at the work being done and express informed opinions.

Yet Classics, by its very nature as a field that encompasses disciplines as diverse as history, philosophy, archaeology, art history, rhetoric, grammar, linguistics, and many others, engages a large body of stakeholders who are not specialists. In fact, this is precisely the reason why the discipline of Classics has been conceived as part of the core educational curriculum in the West until recently. For this reason also, the teaching of Latin (and to a lesser degree, Greek) has recently regained some of its popularity in high schools, as parents and educators search for means to introduce children to the Humanities and the study of languages.7 The question then becomes, how to accommodate these different aspects of the field without compromising either quality or accessibility, and in general, how to promote the study of Classics?

The Perseus Digital Library, within which the Perseids platform is nested, has long served such a diverse audience. Perseus' broad mission is 'to make the full record of humanity − linguistic sources, physical artifacts, historical spaces − as intellectually accessible as possible to every human being, regardless of linguistic or cultural background'.8 Naturally, such a mission can never be fully realized, yet the infrastructure that we design now will materially enable or constrict how the next generation will be able to read languages from the past, scrutinize ancient artifacts, and explore historical spaces. With these goals and caveats in mind, the Perseids collaborative editing platform was designed to enable a broad audience to contribute to Perseus, and in general to participate in the creation of knowledge in the Humanities.9

The Perseids platform makes a range of tasks available to its users, from micro-tasks to multi-step editorial projects.10 Students can undertake entire editorial tasks individually or in groups, as was done in Marie-Claire Beaulieu's Medieval Latin class in 2013 with the Tisch Miscellany Collection, a group of manuscript leaves and folios from early printed books preserved in the Tisch Library at Tufts University.11 This project served as a test bed for tasks that were later to be made available in an integrated workflow on the Perseids platform. Now, students have started using the Perseids platform for such tasks. Editing and translation work has started on a 14th-century compendium of English Forest Law preserved in the Tisch Library (see Fig. 1),12 and we intend to finish the edition and translation of the Tisch Miscellany Collection. Within these broad tasks, students can be assigned micro-tasks such as morpho-syntactic analysis through treebanks and named entity annotation through a variety of means including Perseids interfaces, through data imported from Google Spreadsheets or via integration with tools from the Alpheios and Pelagios projects.13 By opening up the possibility for a wide range of external and third party tools to be used for annotation, we test different approaches to scholarship and pedagogy but recognize that an integrated fluid user experience is essential to

**Figure 1:** Ongoing editing work on the Carta de Foresta, 14th century compendium of English Forest Law, Tisch Library, Tufts University.

successful uptake and use of the platform. For this reason, we have also now integrated the Arethusa client-side annotation framework, which enables rapid development of new interfaces for different types of annotations and documents, within a single consistent user interface paradigm (see Fig. 2).14

The methodology behind the development of the Perseids platform is consistent with the project's goals for openness and accessibility. Underlying all architectural decisions is the premise that all texts and data produced on the platform must be fully accessible to the creator of the data at any time, and also available to other users of the platform.

There are different aspects to accessibility. First, in terms of user access, all that is required to create an account on the platform is an account with a Social Identity Provider that supports the OpenId protocol.15 The most common type of account for this is a Google email address, but Yahoo and AOL addresses are also accepted and additional OpenId provider services can be added. We have also included support for authentication via a user's educational institution, through support for the SAML/Shibboleth protocol.16 The user can choose to link this account with her social identity, so that if the user changes institutions, she can retain a consistent single identity on the platform associated with her publications. Support for the OpenID and SAML/Shibboleth protocols also puts the amount of private information made available to the Perseids platform and its end users in the primary user's own control. Perseids never has access to authentication credentials (such as passwords) and the only information a user is required to provide is a nickname for their user id. Although a user may choose to provide their email address, full name, and affiliation, this is purely optional.

Next, in terms of legality, all the data produced on Perseids is published under the Creative Commons CC-BY-SA license.17 In addition, at no time is the data locked into a closed database under proprietary formats. Instead, we use the git version control system to store and manage all texts and data,18 and while the current deployment of the platform uses a git repository which is local to the infrastructure components that read and write data, there are various means by which this data can be retrieved by the end users.

All publications at any stage of editing are downloadable via links in the Perseids user interface, serialized according to standard and widely accepted data formats (the standards used will be discussed further below). In addition, version history and comments for any given file are available to any user of the platform through the user interface. No access controls are imposed on either download or history and commenting functionality, although in order to accommodate needs for use in the classroom, we have given the user the responsibility to share links into their publications, rather than advertising them broadly through the user interface. By the end of the first implementation phase of the project, we will also establish a public-facing clone of the master branch of the local git repository on the GitHub platform. This branch contains all committed publications, i.e. those which are no longer under review.

**Figure 2:** Arethusa Annotation Framework showing a morpho-syntactic annotation of Catullus 51.

Finally, the tools themselves used to create, curate, and annotate texts and data are all open source components, available in public version control repositories such as github, sourceforge, and bitbucket. Public contributions to these code bases are encouraged, and − subject to review by Perseids project staff − will be accepted and deployed on the platform. Should a user or set of users wish to add functionality to one or more of these tools that is not deemed to be in line with the project priorities or goals, these users are free at any time to fork the code bases and deploy their own version of the tools, taking their data with them. The tools themselves are connected via documented APIs and standard RESTful web protocols.

A different avenue we are pursuing for accessibility is via integration with other projects in the domain. The Europeana network of Ancient Greek and Latin Epigraphy (EAGLE) project19 has setup a multilingual Wiki for the enrichment and enhancement of epigraphic images and texts, to provide a basis for future translations of inscriptions into other European languages. However, the wiki approach with open editing practices is a new model for traditional scholarship in the field, and Perseids is integrated with the EAGLE wiki to provide an alternate review workflow which allows translations to go through an editorial board. Perseids is in this case serving as a bridge between fully open wiki editing models and the more closed review circles, by providing an open platform to enable peer and board review for wiki-based publication.

# **3 Pedagogy and Scholarship**

When Perseids is used in class to edit, translate, and analyze ancient documents, traditional pedagogical models give way to a new model in which the teacher becomes a collaborator, guiding students through the process of research. In such a pedagogical setting, traditional top-down teaching methods where the teacher is in control of projects and outcomes and individual students all produce work on the same texts are set aside. Rather, work is produced in small teams or as a broad group with distinct tasks. Such a pedagogical method has proved motivating for students, who expressed enthusiasm at the idea of producing original work. Furthermore, this collaborative method can easily be combined with more traditional lectures or drills in order to vary classroom activities and stimulate different types of learners, from the more passive to the more pro-active students.20

Furthermore, collaborative teaching methods provide a new model for evaluating student work. While traditional assignments are produced on a onetime basis and usually go through only one grading cycle, collaborative assignments can be evaluated multiple times, formally or informally. This component of the Perseids platform is an extension of the Son of SUDA Online (SoSOL) application,which was developed by the Papyri.info project (where it is called the Papyrological Editor).21 This tool supports a workflow that leverages the Git version control system and in which a publication can consist of multiple linked documents, each identified by a stable Uniform Resource Identifier (URI).22 There are no fixed editions; everything is potentially in flux but each change is carefully recorded and vetted via an approval process which passes the documents in a publication through one or more targeted review boards made up of editors and community members. In a classroom setting, the board can be the teacher and teaching assistants, while in other projects the board can be composed of invited experts, or simply all the members of a project team. Such a review method is commonly used in research and forms the basis of the peer-review system on which modern scholarship relies. In a classroom setting, multiple reviews allow students to learn from their mistakes and correct them, cut down on stress, and allow for a longer-term formative experience that shifts the emphasis from grades to learning. The students and the teacher make sure the task is done optimally rather than simply evaluating how it meets a certain standard at first try. Furthermore, the process serves to train students as researchers as they get to experience the many stages of review through which any work of scholarship must go before publication.

Our aim is to support a wide range of publication types for the texts and data produced on the Perseids platform, from micro or nano publications23 to fullfledged digital editions which adhere to scholarly standards such as those outlined by publications like RIDE.24 Some examples of micro publications already supported include the commentary annotations produced by Marie-Claire Beaulieu's mythology students and published on the Perseus Digital Library,25 additions and corrections to linked data sets like the Perseus Lexical Inventory,26 and named entity and date annotations produced via the use of tools like TimeMapper and preserved via ingest into the Perseids repository from Google spreadsheets.27 We also support complete digital editions comprised of multiple documents including transcriptions and translations of source text in TEI XML, complete morpho-syntactic annotations on the text in the form of treebanks, translation alignments, accompanying commentary, bibliography, and other related information. The Fragmentary Texts and Bodin prototypes are demonstrations of possible web based presentations of such editions, always backed by the raw XML, and annotations that are the substance of the data behind the edition.28 Through tools like Arethusa, mentioned previously, we are also exploring approaches to living publications, where members of the community can distribute links to their work in progress and invite feedback. The goal is to support as small or large a contribution to the scholarly discourse as an individual is willing and able to make, always preserving the history of the work, recording provenance information according to standards for research data like the PROV ontology so that work is credited and attributable.29 Perseids team members have also been participating in international research data efforts like those of the Research Data Alliance to ensure we are informed of and follow the best practices in the scientific and scholarly communities for preservation and publication of the data that makes up our publications.30

Collaborative teaching methods also give permanence to student work. While traditional classroom assignments will usually get thrown out after the semester is over and are rarely expanded into further work, the work done through Perseids is published to the web in the form of editions, translations, and annotations, where it serves to support further scholarship and learning activities. In this way, the students learn by producing concrete results, much in the way students in the sciences learn by participating in experimentation in laboratories or students in trade schools learn by working on actual products. In this way, Perseids not only democratizes access to publication, but also gives value to small contributions as well as to large ones.31 For this reason, Perseids will soon implement an e-portfolio module,32 which will pull together all of a user's contributions to scholarship through the platform and make them available as a body of work. The module can be used as a tool for global classroom evaluation, for capstone projects, or as material for graduate school and job applications.

### **4 What is Scholarship?**

Opening up participation in scholarship in this way brings us to ask the question, what exactly is scholarship, and do these methods change it? According to the American Heritage Dictionary, scholarship is 'the methods, discipline, and attainments of a scholar or scholars'. According to this definition, scholarship is about the ways in which knowledge is produced as well as the result of this production, namely, contributions to the advancement of knowledge. Thus, over the centuries, scientific research methods have evolved in order to ensure maximum accuracy of the results. These methods apply to all science, regardless of the field, whether it is in the Humanities or Natural Sciences. At their core, they involve relatively simple principles that correlate the collection of accurate data and its interpretation. In Classics, these principles are seen at work in language training, which is essential in order to understand and use the information provided by ancient documents to the fullest, and in the principles that guide the conduct of textual criticism, archaeological digs, etc. All these methods are designed to collect data in a way that is as accurate as possible so as to form the basis for sound interpretation.

Perseids helps Classicists to uphold these scholarly standards and to make them accessible to a broader population than ever before. Many of the tools offered on Perseids facilitate language acquisition, such as morpho-syntactic analysis through treebanking, which provides a visual and kinetic method to analyze language, as words and clauses are moved around the screen to show sentence structure. This is an effective method not only to gain understanding of language, but also, to display one's understanding of a sentence or group of sentences and justify interpretations. In this way, morpho-syntactic analysis offers learning tools that are also intrinsically scholarly.33 Similarly, alignment tools developed by the Alpheios project offers readers who have no knowledge of the original language insight into the text itself, and also allow justifying translation choices.34 As for textual criticism, the editing tools available in Perseids are designed to make the collation of textual data as transparent as possible. The Imgspect tool,the design of which was inspired by the Image Citation Tool of the Homer Multitext Project, allows us to link transcriptions directly to an image of the document (this is particularly helpful in the case of inscriptions and manuscripts) in order to justify readings and show the evidence directly to the audience.35 Furthermore, transcriptions of inscriptions and manuscripts are encoded following the EpiDoc standards, which are ultimately based on the Leiden conventions, long accepted in the field as the scientific standard for presenting epigraphical and manuscript texts.36 Finally, the built-in review process available in Perseids and the collaborative focus of the platform helps to uphold the standards of peer review, which are crucial in establishing credibility in any field.

The Canonical Text Services Unique Resource Name (CTS-URN) specification, developed by Chris Blackwell and Neel Smith, working with the Center for Hellenic Studies, is a core standard of the Perseids platform and enables us to connect the work we do today with the long standing tradition of scholarly citation in the classics.37 The CTS-URN specification allows us to translate canonical citations such as Thuc 2.44 and Liv. 1.34 (which have long described chapter 44 of book 2 of Thucydides and chapter 34 of book one of Livy) into a technology independent and machine actionable form.38

These URNs, when combined with the http://data.perseus.org namespace, allow us to provide persistent, stable, resolvable identifiers for any canonical text, passage, or even word as the target for our annotations in a manner that adheres to best practices for linked data.39 We make this data interoperable and sharable by other projects in the field by serializing all annotations. This includes the simple identification of named entities, to commentaries on texts, to the more complex morpho-syntactic analysis, according to the Open Annotation (OA) data model, including provenance information for the creators, contributors, and reviewers of these annotations.40 The inclusion of provenance information allows consumers of the data to make their own quality assessments about the data. And in addition to the persistent URIs for the primary source texts which are the target of the annotation, we can reference and contribute to other established data sets in the domain, such as the Pleiades Gazetteer and the annotations on ancient places aggregated by the Pelagios Project.41

In addition to these methodological principles, the American Heritage Dictionary offers a second definition for scholarship, explaining it as the knowledge resulting from study and research in a particular field. Thus, according to this definition, Perseids users become scholars by the very fact that they engage in such activities. We note that the dictionary does not characterize scholarship or scholars as possessing definitive knowledge on a topic. Rather, both definitions imply a process that results from the practice of scholarly activities through which knowledge is produced, with new data and new interpretations constantly replacing old ones. Knowledge advances on a continuum, with contributions big and small paving the way to discovery. In Perseids, this aspect of scholarship is represented in the equal value given to all contributions, whether they are large editing tasks or the correction of typographical errors.42 For this reason, all contributions will appear in a user's e-portfolio, showing all the aspects scholarship can take.

#### **5 Conclusions**

Perseids permits the practice of scholarship in the traditional sense of the word. Yet, Perseids also transforms scholarship by offering broad access to and engagement of individuals at all levels of expertise, not only to the practice of scholarship, but also to its valued outcome, publication. We encourage and enable users to take responsibility for the scholarly data they produce on the platform, offering the opportunity for it to be published, after review, by the Perseus Digital Library as part of a larger collective body of work while also leaving them free to take it with them and re-imagine its publication by itself or as part of other projects, such as that of the EAGLE network. As a result of this process, the undergraduate students who currently make up the large majority of our user base learn that they are part of a global community of interconnected scholars sharing the responsibility for making more ancient texts than ever before available for analysis and study by all, while still upholding the long-established standards of quality of the discipline. Some of these students begin to see themselves as research partners with their professors, rather than just as students completing an assignment, and discover that they are empowered to publish and disseminate their knowledge in a wide variety of forms and venues. As undergraduates in multidisciplinary courses of study, many of our users will go on to fields well outside of traditional academic structures and we hope that we have planted a seed they will carry with them, leading to their future engagement in opportunities for scholarship, whatever they may be.

#### **Acknowledgements**

This work was made possible by a grant from the Andrew W. Mellon Foundation, '*Developing Perseids: Enhancements to a Collaborative Editing Platform for Source Documents in Classics*', 2013−2015. This work was supported by a Digital Humanities Start-Up Grant from the National Endowment for the Humanities [grant HD-51548-12]. Any views, findings, conclusions, or recommendations expressed in this article do not necessarily represent those of the National Endowment for the Humanities. This work was also supported by a Tufts Innovates Grant from the Office of the Vice Provost at Tufts University. This project is made possible by a grant from the U.S. Institute of Museum and Library Services [grant LG0611032611].

# **Notes**

# **References**

# CHAPTER 10

# **Engaging Greek: Ancient Lives**

James Brusuelas

University of Oxford

#### **Abstract**

Since July 2011, Ancient Lives has recorded well over 1.5 million transcriptions of ancient Greek papyri (over 9 million characters), the work of over 105,000 unique online collaborators. The result was not simply the creation of big data, but the inception of an entirely different way of conceiving and interfacing ancient digital texts. Put simply, Ancient Lives has created something that has never existed before: a database of unedited Greek. We have strings of Greek characters without word division or any modern editorial convention. The purpose of this chapter is to discuss, first, the Ancient Lives' methodology of public engagement, the inclusive process by which the public participates in the fundamental tasks of papyrology (this includes both untrained and the unique users targeted by Almas and Beaulieu). Next, the success of any crowdsourcing project depends not only on data input but also how that data is subsequently processed and utilized. An overview of current development then follows, which particularly addresses Ancient Lives' interest and continual use of machine intelligence and genetic sequence alignment algorithms (examples of successfully repurposed field-specific algorithms, an often challenging process as discussed by Tarte), to process multiple transcriptions of a single fragment (version control), query, data mine, and edit these crowdsourced transcriptions within an innovative digital environment. More importantly, in providing public access to data that was for a century viewed only by a handful of scholars, Ancient Lives continues to engage in changing models of traditional scholarship.

**How to cite this book chapter:**

Brusuelas, J. 2016. Engaging Greek: Ancient Lives. In: Bodard, G & Romanello, M (eds.) *Digital Classics Outside the Echo-Chamber: Teaching, Knowledge Exchange & Public Engagement*, Pp. 187–204. London: Ubiquity Press. DOI: http://dx.doi. org/10.5334/bat.k. License: CC-BY 4.0.

# **1 Introduction**

*It's madness*. Within the field of Classics and its subset Papyrology, that phrase, in one form or another, was often the response to even the slightest mention of Ancient Lives (hereafter AL) in 2010, when I arrived at Oxford to begin work on the project.1 A collaboration between Oxford Classics and Astrophysics,2 AL was to join the many other crowdsourcing projects hosted by the Zooniverse.3 As one might guess, upon hearing the word crowdsourcing, such a reaction usually came from senior academics. But perhaps the most colorful comment I can recall was the description of AL as the 'bastardization of the papyri,' uttered by a young postgraduate student at an academic gathering in Leiden in 2012, months after the project had launched—I happened to be sitting on the other side of the table and, with arguably too much delight, responded, 'Oh yes, my project.' What a thought, an experiment indeed. Let anyone, trained or untrained, transcribe a papyrus fragment of ancient Greek online. Let the world assist in transcribing the seemingly countless papyrus fragments from the ancient city of Oxyrhynchus, housed in the Sackler Library of the Ashmolean Museum.

Since their discovery this body of well-known fragments has reintroduced to the world texts that have not been seen since antiquity, such as the Gospel of Thomas and the poetry of Sappho,4 and although Oxford has held them for over a century, the opportunity for discovery still lingers seductively; due to the sheer volume of fragments, more texts and authors are still waiting to be found. From its very inception, then, AL touched a distinct nerve: access. Looking back, it was not so much about crowdsourcing but access to viewing unpublished material. What happens if someone with no formal training accurately transcribes a fragment? Worse still, what happens when a self-taught individual, using the same tools available to scholars, contextualizes or even identifies a fragment? The cardinal rule, after all, of working with ancient manuscripts is that their text looks nothing like the modern printed editions through which students and the vast majority of scholars engage their content. A Greek papyrus fragment is a perfect example. It is just a string of characters without word division and little to no punctuation, not to mention issues such as scribal errors, variant readings, new words, and cursive handwriting reminiscent of a doctor's prescription. It is not a simple reading experience. Accordingly, a distinct scholarly identity has been constructed around them; one that, as noted above, cuts across generations. For the laymen to walk in off the street and successfully perform certain academic and papyrological tasks, even if only at a rudimentary level… That idea was not just brushed off, but seemed threatening to some. It seemed that any success achieved by AL would be at the expense of Papyrology and even Classics, or at least demystification of the academic process to a certain degree.

Be that as it may, I found myself in a peculiar position. I was tasked with creating a dialogue between academics, our beloved primary source material, and … everyone else. Better (or worse) still, I had to create this dialogue even if certain segments of my field simply were not interested. Now, it is not that AL was devoid of supporters in the beginning. There were, and still are, many colleagues interested in engaging the general public about Classics, classicists, and the Greek and Latin languages in a living dialogue rather than from any position or notion of 'gatekeeper;' these languages are not oracles nor are we the Delphic priestesses and priests uniquely capable of interpreting them. And so many colleagues and friends have long suggested I write something about my involvement with AL and my ongoing role as its leading voice. For the invitation to contribute to this book, I am thus very grateful for the opportunity (or, better put, the motivation of a deadline) to write a simple essay about my involvement in the development of Ancient Lives and what the project has thus far achieved.

As I write, AL is in the process of being rebuilt for re-launch. This is both to improve its functionality, its overall frontend and backend design (a Rails app about to become a Backbone.js app), and to upgrade the application to conform with current Zooniverse standards. AL is changing, morphing into something else.5 What follows now is nothing more than a simple reflection on how AL initially produced millions of transcriptions of useable data, engaged in machine learning for processing this data, and dabbled in Bioinformatics for the purposes of automated text identification.

### **2 Patterns and Users**

With the lure of discovering new texts of Greek literature or even a new gospel, we always expected classicists of all skill levels to play with the interface. And they did. Nevertheless, although AL embraces the volunteer community as a whole, including trained classicists, development of the interface was always focused on the individual with no knowledge of ancient Greek. So, how does one produce an environment that facilitates participation and contribution from those outside of academia? Pattern recognition.

The fundamental premise upon which AL operates is pattern recognition. It is a task at which the human brain excels. And so one does not need to know the dynamics of ancient Greek grammar and syntax to recognize the triangular shape of alpha and delta (Α, Δ) or especially a familiar shape like nu (Ν). A simple image and a keyboard of Greek characters are all one needs (Figure 1).

Be that as it may, like any evidence of human generated script, character shape is not consistent and the degree of cursive can be slight to severe. Moreover, the alphabet present in the papyri is devoid of any cognitive notion of modern upper or lower case; there really is only an 'upper' case, even though it appears to mimic those distinctions, such as the case of alpha being triangular (Α) or round (α). From a development standpoint, that caused a bit of a

**Figure 1:** Current AL keyboard.

dilemma. There is no 'paleographical' keyboard devoted to the character shapes found in ancient papyri. For a virtual keyboard we only have Unicode character shapes, of which many directly correlate to the later Byzantine Greek minuscule preserved in parchment codices. Moreover, to produce useful data, it is indeed those Unicode characters that are the required input. In a papyrological context, while a trained user could immediately recognize that they are looking for lunate sigma (c) and not medial and final sigma (σ, ς), or that delta (Δ) does not look like the minuscule form (δ) in papyri, the question over what visual data to provide the crowd lingered. Furthermore, from the crowdsourcing standpoint, users not only needed to focus on finding patterns and matching character shapes, but also the intuitive freedom to provide data without being bogged down in a host of variables that would cause hesitation. In other words, that first moment of interface is not a moment for actual training or official indoctrination in Greek manuscripts. Motivation to engage in the task of classification must arise from the simple notion of pattern matching, not necessarily knowledge of ancient Greek or Greek paleography. The user must recognize that the digital tools before them facilitate their contribution. If there were even the slightest hint that formal training was needed, participation by the general public would have most likely been stifled to a large degree. Accordingly, the solution at the time was to provide users with a standard Greek Unicode keyboard, including both shapes that appear in papyri and even those that do not. In addition, to assist with the difficulty that arises as letter shapes become cursive, images of cursive forms were made available by hovering over a given character.

In psychological parlance, AL would most likely straddle both the 'template matching' and 'feature analysis' theories of human pattern recognition. Some literary hands are nearly font-like, and users are explicitly pairing character shapes in an image with a character 'template' in the keyboard. But as documentary hands become more and more cursive, the general feature of epsilon (Figure 2), for example, must be recalled when classifying cursive character shapes.

In late July of 2011, when AL went live, the Zooniverse had a community of roughly 400,000 users – it is now over 1 million. To a large extent, and considering the positive reception during beta testing, we knew the Zooniverse community would provide data, at least enough data to evaluate the experiment. But would the general public engage in transcribing ancient Greek papyrus fragments? The question still remained. Fortunately, the answer was not only a resounding 'yes,' but AL, due to the media attention we received, even brought in new users into the Zooniverse. The general public was and is indeed interested in what papyrologists do. Moreover, the characters shapes themselves, both clear and cursive, and the random bits of ancient art visible on some papyrus fragments inspired the imagination of the volunteer community.6 And as the world outside academia became more informed about this vast number of papyrus fragments from Oxyrhynchus, the idea of contributing to the discovery of a lost work was a profound source of motivation. By the end of the first year of the project, AL recorded 1.5 million transcriptions, roughly 7 million Greek character classifications – currently over 9 million have been recorded. What became immediately apparent, and not unexpected in the Zooniverse, was the appearance of so-called 'power' or 'super' users, individuals who contribute hundreds of transcriptions as opposed to the majority of users that were only producing a few.7 And so there was this segment of the crowd that wanted to talk with papyrologists and classicists about what they love, discuss ancient literature and history, and simply help. This nodal point of interaction and outreach is unique. This is Classics in culture, happening in real time and not defined by the parameters of a classroom or even a university campus.

Despite such interesting variables, however, no in-depth study of AL users, both in the context of the Zooniverse community as a whole and in relation to other crowdsourcing projects, has been conducted. To get a feel for the AL community one must visit Talk. Every Zooniverse project is equipped with a Talk section, a place where the members of a specific community of a given project talk to one another, as well as project members. This is a place to isolate interesting images, flag them, ask questions, and essentially acquire further knowledge about a project's data. For the AL community we should note their engagement in self-learning. As an expert, one of the unique aspects of working with users in Talk is not being the never-ending voice of 'no' or 'wrong.' They may be there to help you, but they did not sign up for your class. This is an

**Figure 2:** Cursive shapes.

exploration in real time, in their private time. The biggest mistake would be to drive volunteers away by constantly hammering home what they do not know. The user who actively engages in Talk is someone that wants more information, wants to improve the accuracy of their classifications. As an expert, your voice is simply one of information, not evaluation. After providing basic guidance it is often better to step back and let the users help each other. After AL launched and users began to get acquainted with the various kinds of handwriting present, it was not long before individuals began posting online links for Greek paleography, especially those showing examples of the more difficult cursive forms of certain Greek characters. Soon users were helping each other classify the more difficult forms of cursive epsilon, for example. And discussion pertaining to the AL keyboard and characters shapes not present in the papyri become commonplace, especially the topic of lunate sigma vs. the medial and final sigma forms of the later Greek minuscule.

How did AL generate so many crowdsourced transcriptions? We simply gave the crowd images, a virtual Greek keyboard, and an intuitive task.8 With so many users in the Zooniverse, AL then generated what can be described as Big Data, a term not necessarily devoid of ambiguity. But in our case, since AL creates multiple transcriptions of a given fragment, processing the data posed a great challenge.

# **3 Enter the Machine: Consensus, Line Sequencing, and Greek BLAST**

Having over a million transcriptions tucked away in a MySQL database allowed for easy interaction with AL data, if one knew how to write a MySQL query. The number of papyrologists and classicists that can, however, never seems to be very large. Consequently it became rapidly clear that AL required serious computational support if its data was going to be made useful to those without any knowledge of coding.9

One of the principal tenets of papyrology is that more than one pair of eyes is always better. Whether a student or an experienced scholar, establishing a transcription and eventually a final edition is not produced in isolation. We often see different shapes, and in reconstructing a fragmented ancient text the most accurate product is never the result of just one pair of eyes. The size of ALs papyrological database may have been unprecedented, but the required methodology for processing was no different. For each fragment we needed a consensus transcription. How to extract a consensus from the database then emerged as a machine learning challenge. We needed an algorithm that could be trained to batch process millions of transcriptions. Accordingly, it also offered the opportunity to bring the transcription data face to face with the experts.

To tackle this problem AL collaborated with the Minnesota Supercomputing Institute (MSI) and the departments of Classics and Near Eastern Studies and Physics and Astronomy at the University of Minnesota. Dr. Haoyu Yu from MSI was tasked with writing a consensus algorithm. In doing so, one must remember that AL is very different from a transcription project like Transcribe Bentham, whose input is plain text and supplemental XML tags.10 Again, if you want the world to help transcribe ancient Greek, one cannot assume their varied devices are equipped with the necessary Greek keyboard. Instead of recording plain text, a virtual mapping is employed. For each click on a papyrus image, the database not only stores the Unicode character selected, but also the relative click location as x,y coordinates. For the aggregation of user clicks, the initial approach was written in Matlab, employing kernel density estimation—that is, mathematically inferring the likelihood that a variable will take on a given value—to isolate consensus clicks and letters. Besides giving different transcriptions, users will also not click the same exact location on an image, resulting in both multiple characters and multiple sets of x,y coordinates for one character position. Looking at the multiple transcription data of one fragment, the algorithm essentially takes the x,y coordinates for each click position and distributes them into a number of bins according to the search radius, a number determined by multiplying a user-specified kernel width by 2 (the default value is 8 if no kernel width is specified). Within each bin the algorithm finds a consensus letter by identifying the highest kernel density peaks. The x,y coordinates of those peaks are then clustered to create consensus characters and their locations (pixel locations), whereby a virtual image of the fragment can be visualized (Figure 3).

Training the algorithm to successfully render consensus also meant evaluating the resulting user consensus. This was accomplished by performing kernel density estimation against a select group of fragments transcribed by volunteers and then compared with the transcription of expert papyrologists. On this select group of fragments, which included examples of clear literary hands, semi-cursive, and cursive documents (marriage certificates, land leases, personal accounts, private letters, etc), we created a correspondence between the expert's characters and locations and that of the consensus. For clear literary book hands, as seen in Table 1, comparison yielded the following.

**Table 1:** Consensus evaluation.

AL volunteers, as a community, could thus provide excellent data. Users were capable of providing transcriptions that were nearly identical to those given by experts. That said, gathering good data from a clear literary hand was never really in question. It was the idiosyncratic hand styles and cursive writing that posed the largest potential problem. Conducting further isolated investigations we began to see what was expected. Looking at 31 examples of semi-cursive scripts, the percentage of agreement dropped to 65%, while 14 examples of very difficult cursive hands yielded a percentage agreement of only 51%.

Although consensus characters could be successfully gathered, kernel density estimation in Matlab proved to be a computationally cumbersome task. It took multiple days, hundreds of hours, to process the data. More recently we addressed this issue at Oxford. Alex Williams, research programmer on the Proteus project,and Dr. John Wallin of Middle Tennessee State University developed the stepwise approach using the high level programming language Python.11 This new method utilizes the recently established concept that members of the Zooniverse community who complete more classifications, the socalled 'super' user, demonstrate a higher ability to correctly classify data than those who complete fewer classifications. This new algorithm thus identifies the user that has made the most number of clicks first and isolates their character positions as potential nodes of consensus. The remaining clicks are then either merged according to pre-existing locations or, depending on their frequency, established as another possible node of consensus. Once finished, a centroid of each agglomeration of clicks is isolated, yielding a consensus letter. Unlike Matlab, the Python script processes the data in minutes. In a Big Data context, this was quite an achievement. However, we did not intend stepwise to supersede kernel density estimation entirely, as both have their merits. Speed is obviously the benefit that comes with stepwise. But the Matlab approach, though slow in processing time, records and allows visualization of all the user data for a given fragment. In comparing user transcriptions of cursive documents with expert transcriptions, we noticed instances where the correct character was essentially hidden under the incorrect consensus character. More evaluation needs to be conducted in order to fully grasp how the AL pipeline might processes the more difficult cursive manuscripts.

The purpose of AL was to explore new methods that could potentially increase the pace at which scholars study and organize this massive body of fragmentary ancient texts, and the fundamental way to do that is through transcriptions, which are important for identifying and contextualizing fragments. This is how we determine what is Homer, Demonsthenes, Simonides, Pindar, etc. Although both the stepwise and kernel density methods could extract a consensus transcription, the output consisted only of characters and x,y coordinates, not an actual text file of Unicode characters in lines corresponding to the papyrus image. To create lines, Dr. Wallin created another Python script to identify the presence of lines based on gaps of vertical space between neighboring y-coordinates. As shown below in Figure 4, the code smartly deduces lines.

The creation of usable strings of Greek Unicode was perhaps the most important achievement for AL; it also completed the initial AL pipeline (Figure 5). From the moment of launch, we proved that the crowd was interested in transcribing, but the onus was always on us to turn their volunteer efforts into useful data. And with these strings there was always one target in the distance: algorithmic identification of fragments.