Facing Virtual Restoration

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Silvia working on the 3D modeling of the wooden sculptures. Image courtesy of Silvia Sansano Colomina

 By Silvia Sansano Colomina

The fast development of computer technology during the last few decades has led to the birth of virtual restoration in the late 20th century. Not long after, in 2009, its implementation was recommended for the interpretation of heritage by the London Charter. Despite this, it’s still a new topic, and there is a considerable lack of consensus in our field in terms of terminology and especially in methodology. This should come as no surprise, if we think about the number of resources that are used globally for the development of areas like imaging, data science and computer learning and we compare them to the conservation field; it seems completely logical that many difficulties may arise in terms of keeping updated on those improvements that end up being useful for us.

 A key part of our work as conservators is in making decisions about which values are most important to preserve in each individual case, taking into account that prioritizing certain values can force us to downplay others, which certainly can be a painful decision. Considering that any intervention is a traumatic event for an artwork, even if needed, the idea of obtaining a larger amount of information with no extra damage to the piece seems an improvement to the traditional conservation process.

And even when it is decided that the proposed intervention on an object should not be conducted after a virtual restoration campaign, there is evidence that these virtual restorations allow interventions—when they do occur—to be much more curative, leaning closer to a criteria of minimal intervention. Thanks to virtual restoration, it is possible to increase flexibility on treatment criteria and experiment with crossing generally accepted limits without consequences. For example, by creating a digital twin, a conservator can carry out analyses and treatments that would not generally be considered ethical or possible to take place on the original. Being able to work out new possibilities can make the decisions taken on the original object a little bit less painful as they are taken with extra knowledge and options gained through proxy testing.

During a project that took place between the University of Alicante and the Archaeological Museum of Poznań, I was able to incorporate several 3D technologies into the restoration process of carved wood sculptures. The process started with the photogrammetric documentation of the pieces before any physical restoration, and thanks to the 3D models we then created, it was possible to understand the precise location and extent of the damage and alterations on the sculpture. We then carried out the material stabilization to guarantee the physical-chemical stability of the materials, including the steps of disinfecting, cleaning, consolidating and adhesion of fragments. Once this preliminary part of the treatment process was completed, we carried out a second photogrammetric capture with the aim of obtaining 3D models that, besides being an important part of the documentation process, would be used as the digital twins on which a virtual restoration could be carried out.

For this project, we divided the virtual restoration into two phases. Firstly, during the mesh reintegration, both the mesh and the texture were corrected in order to eliminate alterations such as cracks; the volume of the model and the UV map were edited, removing the alterations. Secondly, while working on the reconstruction of missing parts—and after studying the morphology of the model—new volumes were generated starting from basic shapes and then applying modifiers and digital sculpting to achieve the desired volume. Once the missing parts were obtained, a texture was applied by mixing PBR textures and other parameters in a node system.

Mesh: A collection of vertices, edges and faces that represents a 3D object.

UV map: A 2D image that contains the unwrapped faces of a 3D model.

Modifiers: Chainable elements that contribute to sculpt and edit objects changing the geometry and properties.

PBR texture: (Physically Based Rendering)  Texture workflow that aims to simulate how light reacts with a model combining different texture maps.

Node system: In this case, the network that connects different sets of data—like textures, colour mixers or shaders—to provide the necessary information of the material during the render.

In this case study, incorporating virtual restoration allowed us to improve the visual and aesthetic aspects of the artwork along with its legibility.  The digital 3D models will also make it possible to accurately compare our two models, taken at different times and stages of treatment, to the original sculpture in the future; it will be interesting to monitor the state of the original sculpture over time compared to the 3D models.

There are so many other advantages to integrating this methodology into a treatment. For instance, regarding imaging, it is possible to carry out a preliminary study to visualize several potential treatments including minimizing or differentiating old restorations, conducting quantitative analysis on surface alterations, observe hidden areas obscured by exhibition hardware and many more. It should also be noted that any historical documentation for the piece, or for similar pieces, is not only essential in creating the most authentic virtual reintegration of losses, but this documentation can also be used as evidence identifying the areas on the 3D model that are original versus restored.

Considering all the aforementioned advantages of using 3D scanning documentation, it's surprising that, according to a survey carried out in our previous project, the number of professionals who integrate this technology is relatively low and the majority of whom are young professionals. A possible reason for this is a certain conservatism observed among professionals above a particular age when modifying work methodology that could be associated with the digital generation gap. Despite this, our profession’s acceptance of digital documentation and restitution of missing parts is overwhelming, and most conservators have considered virtual restoration as complementary to the treatment process.

One of the most prevalent concerns of conservators who implement virtual restoration is the preservation of all that digital information. Although it may seem quite the opposite, according to UNESCO the survival of digital heritage is much less assured than traditional tangible media. Because of this, preventive conservation is essential in evaluating the risks that threaten digital documentation, including anticipating possible threats that could arise in the future. Otherwise, digital objects could become impossible to display or access, could lose their context, or data could become partially or totally corrupted.

To avoid these situations the Digital Preservation Coalition (DPC) provides several recommendations. These can be divided into two groups. Firstly, it is important from the beginning to use open files without encrypted data, making a careful selection between useful files and expendable ones, creating standardized files, incorporating the necessary metadata and registering the used workflow. Secondly, we should focus on the digital information that must be maintained by the owners of those files. To achieve this, we should create backup copies of all files, including metadata, to ensure that the data exists in at least two physical locations. In addition the DPC recommends performing periodic updates including rewriting in new media, keeping files in order and organizing them according to a specific nomenclature.

The digital era is here to stay, and many conservators will have to acquire new knowledge to be able to preserve digital art, but there are so many other areas within our work as conservators (like those discussed in this paper) to which this interdisciplinary point of view can be brought. With initiatives like ConCode (which created a network for applying data science in the museum world), support from universities and other education institutions, we have already taken the first steps in this direction, and it is up to us to take it further.

Additional Resources

Choy, S. C., Crofts, N., Fisher, R., Lek Choh, N., Nickel, S., Oury, C., and Ślaska, K. (2018). Directrices UNESCO/PERSIST sobre selección del patrimonio digital para su conservación a largo plazo. Available at: https://repository.ifla.org/handle/123456789/1220

Sansano Colomina, S. (2021). Intervención restaurativa sobre dos tallas del s.XVI. Un caso centrado en la reconstrucción virtual, Máster en Patrimonio Virtual, UA.

Acknowledgments

I would like to thank both the Universitat d’Alacant and the Muzeum Archeologicne w Poznaniu for offering me this opportunity. Special thanks to conservator Jarosław Jaskulak for his enthusiasm and guidance during the treatment of these pieces.

AUTHOR BYLINE

Silvia Sansano Colomina graduated in conservation and restoration of heritage at the Universitat Politècnica de València and has international experience in countries including Portugal, Bulgaria and Poland. She recently finished her master’s degree in virtual heritage at the Universitat d’Alacant and is particularly interested in preventive conservation and how technology can help prevent damage in heritage.

 

(Read the article and see all the 3D imaging of the wooden sculptures in the December-January 2022 "News in Conservation" Issue 87, p. 22-26)

 

 

 

 

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Thanks to virtual restoration, it is possible to increase flexibility on treatment criteria and experiment with crossing generally accepted limits without consequences. Being able to work out new possibilities can make the decisions taken on the original object a little bit less painful as they are taken with extra knowledge and options gained through proxy testing.
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