The Ghent Altarpiece: Sonoptics & Augmented Reality

January 11, 2022 · Review-essay

lower register central (inner) panel from the Ghent Altarpiece

Fig. 1: lower register, central (inner) panel from the Ghent Altarpiece. Image: public domain/wikimedia

The Ghent Altarpiece has recently been restored. It is now on display in the Sacrament Chapel of St Bavo’s Cathedral, accompanied by an augmented reality introduction in the Crypt. This review-essay explores a sonoptical reading of the painting and considers affinities between Early Netherlandish techniques of oil painting and the digital world-building of today’s 3D design.

A Technology of Depth

Oil binds pigment. It permits luminescent painting techniques like glazing. Jan van Eyck's facility for this image-making technology established a level of realism in Early Netherlandish painting that has been the subject of much commentary ever since. The Flemish painter, poet and writer, Lucas de Heere (1534-1584), for instance, described the panels of Het Lam Gods as 'mirrors...not painted tableaus' (Depoorter and Van Dan Abeele, 15).

A mirror is typically in front of and beyond its subject, its reflected image seemingly beyond its glassy surface. This double case of the beyond-ness of a physical object and reflected image might cause a subject to incline forward, for closer inspection. But in doing so, the image appears to move in the opposite direction.

So mirrors encourage a kind of interactive play. They induce bodily gestures, forwards and backwards. To make a painting that can be described as a mirror, an artist needs the tools to represent depth. In the fifteenth century, oil—as a medium for pigment, highly suited to the painting of light—assumed this technological function. And under Van Eyck’s control, it dispenses a ravishing luminance.

The Fountain of Life from the Ghent Altarpiece

Fig. 2: 'The Fountain of Life' from the Ghent Altarpiece. Image: public domain/wikimedia. Cropped original file.

The Sounds of Things

The union of means and skill in the Ghent Altarpiece permits a vital sense of a thing’s material nature—how it might feel to touch; how it might move, if subject to some force; how it might have some existence, beyond our own etc.

Van Eyck inscribes the materiality of things by attending to their illumination. As viewers, we perceive the panel paintings and think about what their depicted objects do. We call upon our experience as we imagine another world, replete with effects and their causes.

The panels of Het Lamb Gods induce our capacity for perceiving depth and sensing motion in three-dimensional space. The displacement of air particles is, after all, the cause of sonic experience. So there is a sense in which the painted panels of the Altarpiece let us imagine the sound of things in motion. They have a sonoptical quality.

Take the fountain in the central panel of the lower register(fig. 2). The style of painting renders the physical properties of water, beyond its light-reflecting nature. There’s a gradual increase in the spaces between water jets with increasing distance from the spout.

The rate of change in the size of this negative space suggests the gravity-induced trajectory of liquid. But the water-painting inscribes another kind of movement. It show us the movements of artistic labour: the traces of prior acts of mark-marking.

The dashed discontinuities in the water-lines are signs that a pigment-laden applicator was once applied to, drawn across and removed from the surface of a Baltic oak panel. We attend not only to the painting of movement in an image, but also, to signs of the movements needed for painting that image.

Notably, Van Eyck paints lines to depict light, as well as water. The white-gold rays that descend from the top of the panel are diagrammatic. We might imagine a small arrow, appended to each ray like an illustration in a scientific textbook, showing the trajectory of something we do not actually see.

In contrast, there is nothing diagrammatic about the jets of water. We might well perceive something like these blanched linearities in the corner of an eye on encountering a real fountain. The use of line across diverse phenomena bridges the difference in their materiality. I am reminded of the thirteenth-century English philosopher, Robert Grosseteste, who claimed that light was the first form of all things.

My eye stops following these lines of light just before they exit the frame and traces, instead, the playful springs of water. The frequencies of light are far higher than those of sound. So as I enter the audiogenic realm and attend to sounds of liquidity with my ‘inner’ ear, there is a strange transduction: a slowing down of things.

The Annunciation scene from The Ghent Altarpiece

Fig. 3: The Annuciation (upper register, outer panels) from The Ghent Altarpiece.
Image: wikimedia/public domain
. Cropped original file.

Encounters Between Worlds

The catalogue for the exhibition, Van Eyck: An Optical Revolution (Museum of Fine Arts, Ghent, 2020), notes the innovative way Van Eyck paints cityscapes and ‘by doing so introduces parts of reality into his paintings’. (Depoorter and Van Dan Abeele, 46). It also notes that there has been some debate as to whether the houses depicted in the Annunciation panels (fig. 3) were painted after real buildings in the city of Ghent.

Regardless of the truth, Het Lamb Gods mixes the real and the imaginary. It is also painted in a way that queries the boundary between the panel and the viewer. The Annunciation of the upper register, outer panels, for instance, stages an amalgam of light sources, suggesting that the viewer’s position contributes to the illumination of the scene, via the painted shadows of the lower-right corners (ibid., 54; see fig. 3).

So it is fitting that the new augmented reality introduction to the altarpiece is characterised by encounters between the physical and the digital. The experience makes an apt prelude to viewing the work of a painter who ‘plays with various levels of reality in which the real world and the painted world become as one.’ (ibid., 54).

As a participant in this digital experience I put on a headset and set out on a journey, my path indicated by virtual arrows. My attention was variously captured by real-time 3D digital renderings of Van Eyck’s studio and related themes––apparently right in front of me––and real, historical artefacts, viewed through the translucent plastic of my visor.

Some of the latter were in freestanding exhibition cases—a manuscript scroll, for instance. Some were at floor level, such as Hubert van Eyck’s grave. Others were directly above my head, like the paintings on the pillars of the crypt. And so I found myself inclining, slightly, towards the things I saw, both digital and real, my body’s movements in concert with my curiosity.

An Intervening Zone

Designers often source digital objects or ‘assets’, which are in some elementary state, before importing them into a virtual world of their creation. These objects may be in the form of geometric constructions, for instance, or real-world sound recordings. In working with them in the digital domain, a hybridity develops, which rapidly obscures all signs of their origin and elemental nature. This process of defamiliarization is characteristic of digital arts practice.

The composition of elements in Het Lamb Gods shows something of an analogous way of working. There is a borrowing of familiar forms that calls upon the viewer’s experiential knowledge of places and things (the buildings of Ghent, the movement of water etc.). Yet there is also a sense in which a thing’s capacity is extended beyond its real nature. Water in the capacity of light, say.

The historical gap between this digital introduction and Van Eyck’s fifteenth-century oil-painting is marked by a transitional journey that visitors undertake before viewing the newly restored Altarpiece. Having finished the introductory tour, I returned my headset to the attendant and made my way to the ambulatory in the Cathedral, via several flights of stairs.

The effect of this ascending journey was to dim the memory of digital emanation. I emerged into a place where daylight was filtered by tracery of stone windows and shadows were eased by the fill of electric light. I kept moving forward, curving to the right, following the walls of the choir, beyond the stillness of side chapels.

Finally, I reached the Sacramental Chapel and the multi-million-euro encasing of the altarpiece. I had crossed an intervening zone and exchanged one technology of image-making for another. I saw what is said to be the most stolen painting in history, its reality revealed by the reflection of light on pigment, bound in oil.


Depoorter, M. and Van den Abeele, L., Van Eyck: An Optical Revolution. Ghent: Museum voor Schone Kunsten, 2020.