To See is to Understand: A Virtual Reconstruction of the Main Altarpiece of the Church of the Holy Spirit in Évora
- ccconservacao
- Jul 5
- 7 min read
Updated: Jul 6
To restore one needs to undersatand. Before any intervention begins, diagnoses are made, data is gathered, stories and materials are cross-referenced. Often, what once seemed lost – through deterioration or forgetfulness – resurfaces. The Main altarpiece of the Church of the Espírito Santo, part of the former Jesuit University and now the University of Évora, is one such case. It has survived the centuries bearing visible marks of time: changes in use, ownership, ritual and meaning.
In 2015, after analysing all the information collected during the diagnostic phase, we decided to go further. We developed a virtual historical reconstruction of this altar, in a multidisciplinary project that explored the potential of infographics as a tool for scientific outreach. The aim was simple: to experiment with new forms of digital communication – to make visible what can no longer be seen, and accessible what often remains confined to academic circles.
Ten years later, that purpose still holds. This text revisits the process, the challenges, and the relevance of communicating cultural heritage in a clear, rigorous and engaging way.
An Altar, a Hypothesis, a Platform
The first time I saw the main altarpiece of the Church of the Espírito Santo in Évora, I had the impression of facing an absence. There was something solemn there, but also incomplete. The woodcarving, though rich, was worn, with gaps, faded colours, and a central throne whose stylistic language clashed with the rest of the ensemble. More than an object, the altarpiece felt like a puzzle. And, as so often happens with heritage, what was missing wasn’t just material – it was memory.
I began by surveying the entire structure, documenting the visible pathologies. But I had the opportunity to go further. I found fragments that offered clues to missing parts; I carried out analyses to identify materials that, to the naked eye, were mere residues; I delved into archives in search of those who had once written about the altarpiece and its construction. Day by day, when I saw the church's priest, I would say, “I have a new theory!” He would laugh. Each day I brought a new theory. But he listened – and encouraged me to keep investigating.
The idea of virtually reconstructing the altarpiece arose from a desire to better understand what had once existed there. But also – and perhaps more importantly – from the need to share that understanding.
At the time, I was working with the HERCULES Laboratory at the University of Évora. Professor António Candeias, the lab’s director at the time, was always a driving force for exploring new ideas. I remember asking him whether I could write a short piece for the lab’s newsletter, using a “before and after” image of the altar. His answer was immediate – and he went further: he introduced me to other team members with whom I would go on to work on design, programming and digital visualisation. That shared vision led to the creation of the website – an interactive platform that replicated, in accessible digital form, much of what I had already analysed, but now with a new ambition: to communicate further and to wider audiences.
Research projects often generate large volumes of data, but most of this data never reaches the public – or if it does, it’s in a form that’s hard to grasp. So how can we make knowledge visible? How can we show without oversimplifying, and without compromising rigour? These were the questions behind the digital platform we created in 2015: an interactive infographic, designed to function like a museum exhibition – but online.
The Altarpiece and Its Fragmented History
The Church of the Espírito Santo was once part of the Jesuit University of Évora. Construction began in 1566, on the initiative of Cardinal D. Henrique, and the church was inaugurated in 1574. The main altar, a Mannerist gilt wood altarpiece, is believed to have been commissioned around 1631, according to the date inscribed on the tiled walls of the chapel.
Over the centuries, the building passed through many hands: the Society of Jesus, the Third Order of St. Francis, the Casa Pia (an educational charity), the lycée, the university institute, and today, the University of Évora. Each phase left its mark – some are documented, others only visible in the physical changes to the space. The main altar, in particular, underwent several transformations: lost sculptures, structural modifications, and the insertion of later elements, such as the Rococo throne in the central niche. The original paintings that once adorned it have disappeared. Its current state is that of a surviving body – but an incomplete one.
Despite documentary gaps, a few key sources were essential for this project. Chief among them is Evora Illustrada, a manuscript by Jesuit priest Manuel Fialho, written in the early 18th century. It contains a detailed description of the altarpiece and its iconography, which was crucial in identifying the lost elements and proposing a reconstruction.
What Matter Reveals: Analysis and Interpretation
Understanding an altar requires looking beyond its form. The study of materials and techniques was crucial in uncovering how it was made, what colours it once bore, and how it was altered over time. We carried out in situ XRF analyses, collected micro-samples for stratigraphic cross-sections, and used techniques such as optical microscopy, SEM-EDS and micro-Raman spectroscopy.
The results revealed a richly decorated surface, crafted using water gilding techniques over layers of gesso and red bole. Gold leaf was then decorated – covered with vivid colours like green, blue and red – and worked with styluses to create patterns that allowed the gold to reappear beneath. Pigments such as cinnabar, azurite and lead white were identified in the flesh tones and decorative backgrounds. Scientific analysis confirmed hypotheses – for instance, the presence of polychromy in areas that today appear simply as worn wood.
One particularly telling example was the detection of green pigment in the lower parts of the columns – almost invisible from ground level. Another was the study of the deep blue decoration on the cartouche of St. Francis Xavier, which Raman spectroscopy identified as azurite.
Left: Stratigraphic sample of a column decoration, showing a layer of green pigment (4) over gold leaf (3).
Right: Raman spectrum identifying azurite in an cartouche. Analysis performed by Margarida Nunes, HERCULES Laboratory.
Reconstruction as a Way of Thinking
The final image is not a reconstruction in the traditional sense. It is a visual hypothesis, carefully grounded in data, that synthesises all the information collected. The starting point was a digital photograph of the altar in its current state. Onto that image, using Photoshop, we reconstructed missing sections, duplicated symmetrical elements, and reintegrated colour.
Some features were "borrowed" from other churches: similar sculptures, decorative details, paintings. The main altarpiece of the Church of São Roque, in Lisbon, served as a model to identify likely sculptures. The missing paintings of the Pentecost and the Dove of the Holy Spirit were adjusted from analogous compositions. The final image, then, is not a return to the past, but a way of thinking about the past through visual interpretation.
Left – Saint Dominic, polychrome wooden sculpture currently on the altar.
Centre – Saint Ignatius of Loyola, polychrome wooden sculpture (Inventory no. Esc. 93São, Santa Casa da Misericórdia de Lisboa / Museu de São Roque – Photo: Júlio Marques).
Right – Detail of the main altarpiece of the Church of the Jesuit College of Funchal, Madeira (Photo: Tiago Dias, Faculty of Arts, University of Lisbon).
The Website as an Interactive Exhibition
Based on the reconstructed image and all supporting data, we created a digital platform designed as an interactive exhibition. Its structure mirrors that of a museum: an entrance, an exhibition hall, a interpretation centre, and a visitors’ log.
At the entrance, the visitor finds a “before and after” image of the altarpiece. By moving the cursor or finger across the screen, the transformation is revealed. The exhibition section presents interactive 2D and 3D infographics. The interpretation centre offers texts, timelines, historical sources, and complementary materials. Finally, the visitors’ log encourages participation, allowing users to leave comments or questions.
The platform was developed using straightforward but effective tools: HTML, CSS, JavaScript, Photoshop and Illustrator. The goal was not to create a comprehensive database, but rather a proposal – a visual and accessible synthesis capable of engaging both researchers and the general public.
3D Models and the Gesture of Looking Closely
Photogrammetry made it possible to capture surface and relief details that traditional photography could not. It was not without its challenges – gold leaf, with its reflective surface, posed difficulties for 3D modelling. Still, with careful post-processing, we successfully created 3D models of several altar elements.
The cartouches, for instance, were modelled in two versions: one in colour, close to the original, and another without colour, designed to highlight the relief. These models serve not only as high-precision digital records, but also as tools for visual exploration – objects that can be zoomed, rotated and examined up close, almost touched.
Left – 3D model of a cartouche in colour.
Right – 3D model of the same cartouche without colour, emphasising surface relief (rendered by Frederico Henriques).
Curiously, it was through the 3D models that we identified alterations in the altar that were otherwise invisible. In one particularly striking case, photogrammetry revealed the replacement of a cherub’s head in one of the cartouches. It had been lost at some point and substituted by a similar carving. To the naked eye, the change was subtle enough to go unnoticed – but the 3D model clearly revealed the difference.
Ten Years Later: Why It Still Matters
Ten years have passed since the creation of this platform. Technologically, much has changed. But the essential remains: the need to make the knowledge produced in universities and research centres accessible. This project was an attempt to open a window between two worlds that often remain distant: academia and the public.
The web-based infographic proved to be an effective bridge. It didn’t just present results – it sparked interest. It made visible what had been invisible. In many ways, this blog post shares the same intention: to communicate, clearly and compellingly, what was done, and why it still matters.
✪ Link to explore the project: https://www.hercules.uevora.pt/retabuloevora/
✪ Link to the published paper also about this project http://hdl.handle.net/10174/19560
