This is the source
Cleaning and provisional restoration treatments on
This paper presents a methodological solution of approaching the problem of restoring the medieval
The painting was in a bad condition and has stayed in the museum depot for decades. Its paint was obscured with dirt and yellowed varnish. Furthermore, it contained many discolorations, darkened retouches, and overpaints. When it was taken out of the depot for the
, small scales, applied with a gouge) (Figure 2.). The blue azurite layer that remains visible today is old. It probably dates from the late sixteenth or early seventeenth century, yet it was not the original intention of the Lindau master.tremolierung
This leads to an important dilemma in the restoration of the painting. Should the
blue layer be removed as it is not part of the original work? This would mean a large
and irreversible intervention in the painting, which opposes the ethics of
conservation practice. To prevent this, the dark blue layer can also be maintained.
It was applied not long after the creation of the work and it is therefore part of
the life story of the painting. The owner of the work decided to have it painted
over, perhaps because of a change of taste or perhaps a bad condition of the golden
Traditionally, the golden background of medieval panel paintings is connected to the
divine space. Wölfgang Schöne aptly called it the echo of
Paradise
(Schöne, 1954). Another vein of scholars led by Ernst Gombrich
has stressed the importance of the materiality, or, in his words: the thingness
of gold
This report will not deliver the final answer to this complex question. However, we aim to propose a methodological solution that potentially can serve both sides of this discussion: a virtual restoration of the painting using a 3D scan and a 3D print of this restoration or the original work. In this project, for the first time, the virtual restoration of the work is presented as an argument that plays a role in the conservation process. Here we would like to share the steps we have taken so far and look into the future of this project.
The basis for the digital restoration of the Lindau Crucifixion was a 3D scan of the
panel. To record the current state of the panel in terms of color and topography, the
Lucida 3D Scanner was used normal. These cameras take black and white videos of the
laser’s trail, which are then processed as relief information into a grayscale depth
map, using a geometric information system (GIS) and shaded render formats.
The combination of laser scanning and black and white video results in the capture of
the panel’s topography at a high resolution (up to 100μm).Lucida 3D scanner,
https://www.factumfoundation.org/pag_fa/1478/lucida-3d-scanner. Accessed
09 September 2021.
A downside of this technology, in contrast to photographic methods, is the fact that
the color information of the panel had to be recorded separately. This was done by
using panoramic photography in combination with a two-direction lighting system. In
contrast to regular
parallel photography where each
image is taken with its own view point, the panoramic method uses a single point from
which the whole surface is recorded in smaller sections, arranged as a mosaic of rows
and columns
The color information was combined with the heightmap that was recorded by the Lucida Scanner into the final 3D model. The Lucida's capacity of working with 3D information as grayscale depth map images, avoids the need of working with cloud points or polygon meshes. Combining color information with a 3D scan is much more efficient using a GIS map and the final model can be edited easily, making this a user-friendly method of 3D scanning (Figures. 3,4,5.).
Additionally, the digital model will be supplemented with data resulting from other
types of material research that will be carried out during the conservation process
of the painting (e.g. X-ray, ultraviolet, infra-red analyses)
The 3D model of the painting was the basis of the virtual restoration of the work to
its earlier state with the golden background. Not only the appearance (now blue,
originally gold leaf) had to be restored, also the geometry (
We created a virtual copy of the painting that could be rendered in real-time. The
low-frequency geometry, such as the large-scale curvature of the panel, was mapped to
a planar mesh with 16x16 quads. High frequency details were applied to the mesh with
normal mapping, yielding a convincing virtual object suited for real-time
applications
The panel was rendered using Blender’s Eevee renderer for real-time rendering and
Cycles for offline, ray-traced rendering.
To virtually restore the object, we assigned both the appearance and geometry masked
regions. Mask A is the set of all points that were originally painted with gold leaf
and mask B ⊂ A only contains the regions with
The appearance for mask A was adjusted by setting the base color to an ochre yellow
blended with imperfections modeled with Perlin noise
The geometry in mask B was adjusted to approximate a reconstruction of the
Based on the previous explanation, it can be stated that 3D scanning the panel’s materials will contribute to documenting highly detailed information about the artwork. Moreover, it digitalizes the panel in such a way that we can modify, manipulate and alter it to our own liking without having to alter the original work. This way, it becomes possible to visualize potential outcomes of future conservation treatments. In our case, we were able to reconstruct the original appearance of the painting, with the golden background.
Subsequently, this data can be translated into 3D printable data, which makes it
possible to create an exact reproduction of the panel in various stages. In this
research two versions will be made: one as-is
with the blue background and one
with the appearance (gold) and the geometry (
The second phase is the application of color. The polymer that is used in this
process has a light gray color. To reconstruct the polychromy of the painting, it is
possible to print the last layer in color. Additionally, layers of transparent ink
can be added to achieve some glossiness on the surface. Although the developments in
improving the quality of these 3D color prints are promising, there still are some
limitations to overcome. One major issue is the quality of color. As this technology
uses inkjet printing and the curing of photopolymers, the colors achieved are not
complex and as a result of the heating process, the color can look grainy.
Furthermore, the material is very stiff, which results in an artificial feel
of the reproduction.
The aim of this project is an exact 3D replica of the painting in its current, and in
its restored state. The current quality of the inkjet printing does not yet meet our
demands for this project.print
is a
basis on which a separately printed two dimensional high quality color image of the
artwork is attached. Lastly, to make the material appearance more convincing,
paramount features of the artwork’s material appearance (e.g. glossiness, varnish)
are added manually. In the case of the Lindau
The creation of exact reproductions using elevated printing generates the opportunity of visualizing and physicalizing the potential effects of decisions made and treatments done during the restoration process. It allows us to think about the way this 3D print could provide a solution to the important dilemma in the restoration of the painting and whether or not the blue layer be removed as it is not part of the original work. Could the 3D print help in understanding and discussing the complexities of this discussion within the field of art restoration. Additional questions that automatically come to mind are: What this type of reproduction means to the original panel? In what way does this second physical manifestation of the panel (in its current blue and its earlier golden state) contribute to the understanding of the original artwork? How does 3D printing a panel affect the value of the original? Could the 3D print potentially have its own value at some point?
The authenticity of art and the role of facsimiles – which are everything but
original, and are often considered as anti-authentic – has been a heated topic of
debate ever since German sociologist Walter Benjamin aura
– into one of exhibition
value magical
encounter with the physical original artwork. Nowadays, art
reproductions are omnipresent (e.g. on mobile devices and posters). The discussion
that Benjamin started has gained momentum and still continues to grow (fake news
,
not knowing what to believe and where to find the truth when information is at our
disposal at any time and any place, the material qualities of original artworks,
carefully guarded in the museum seem to be the one of the only sources that can
validate an artwork — the survivor of the passage of time — as genuine. Consequently,
in conservation practice this has resulted in the prevalent goal to keep and conserve
as much of the artworks' material features as possible in their current state — thus
including
With this information in mind, how can a 3D print, a visually indistinguishable copy yet one without the material features of the artwork itself, mean something to the original artwork? In the case of the Lindau
3D scanning the panel’s materials and the possibility to 3D print exact reproductions
generate the opportunity of visualizing and physicalizing the potential effects of
decisions made and treatments done during the restoration process in two ways.
Firstly, by using the 3D print, the blue background can be documented and
physicalized before it would be lost, due to an irreversible restoration of the
painting’s background to the earlier version. Secondly, when the decision would be
made to maintain the blue azurite layer, the 3D print could be used to show a
reconstruction of the painting to the primary version without the azurite blue layer
that is currently covering the golden background. We asked the participants whether
or not the azurite blue should be removed and what role a 3D print of the panel could
function as a solution for this issue. Here, when proposing these options, in the
discussion it soon became evident that the panel’s value cannot be solely attributed
to its material qualities. In this report we would like to reflect on two arguments
considering the authenticity
of the 3D print that came up during the
discussion.
The first important aspect of authenticity mentioned was the intention of the artist,
which is oftentimes a highly valued quality original
background with the gold leaf in itself could be considered more valuable than the
panel in its current state, with the blue. The latter does not visually simulate what
the Master would have intended, and thus one could argue that the 3D printed
reconstruction of the golden background is closer to the artist's original intentions
than the panel in its current state, thus more significant in terms of
authenticity.
Furthermore, another participant mentioned, what should be remembered when looking at
original artworks (or at their facsimiles), is that the artwork’s current state is
just a snapshot of a single moment in time. Artworks have their own lifecycle which
spans over decades if not centuries, not only in their material composition but also
in their function, communal and social value. Their conceptual value is not set in
stone, it changes over time. This way, an artwork knows many faces
or
identities
. With the help of conservation methods, it can be decided to
freeze the panel’s material appearance. But this does not do justice to the lifecycle
of the artwork. An example of how reconstructions can help to demonstrate this
lifecycle is the recently revealed reconstruction of missing parts of Rembrandt van
Rijn’s
Both arguments show that reproductions of artworks and especially the high-quality 3D printed facsimiles can contribute to visualizing and physicalizing the elements that contribute to the diversity of identities one artwork can have. The authenticity of
authenticities, and identities one artwork can have, such as its artistic and conceptual value to name a few
The question that arises in this case and which we hope to solve using the 3D prints,
is which version will be considered to be more genuine or authentic
: would
this be to present the painting in its current state, conserving its materials the
way it looks today and by considering the blue layer as a part of its history? Or to
irreversibly remove the azurite layer, but coming closer to the way the Master would
have wanted the panel to look and in a way more similar to the way the artwork was
experienced during the Middle Ages? This relates to the question if the availability
of a high quality facsimile of one over these versions will play a role in the
conservation process? How will the restoration committee weigh the availability of
both versions in their decision on what conservation treatment will be applied to the
panel?
Within this research, we want to use a 3D facsimile to see whether visualizing a past state of an artwork can help to get a better understanding of the material changes an artwork goes through, which might aid the final restoration of the original. Although it is a high-quality reproduction based on detailed 3D data and extensive material research opting to be as scientifically close to the original painting as possible, it is important to realize that a facsimile will and can never be identical to a previous state of the artwork. For this reason, it is essential to pinpoint where the differences lie. First and foremost, a synthetic 3D print is different in terms of materials and could therefore never provide an exact and accurate model of the panel in a previous state.
Furthermore, although the way the facsimile looks is partly based on accurate
measurements, it will always be a best guess
. However, the same can be said in
the case of the actual restoration of the original for the interpretation of the past
is always subjective and place and time dependent freezes
them in time. Subsequently, all
three time-freezes
will impact the way the artwork will be perceived and
interpreted for the years to come. For this reason, similarly to the actual
restoration, the way the 3D reconstructed version looks must be carefully discussed.
For instance, one could question that if the background would be reconstructed to a
pristine
state, should the figurines and the tendrils be reconstructed as
well? Or since the figurines and the tendrils are weathered, to what extend should
the golden background be adjusted? Simultaneously, the same kinds of questions can be
asked in terms of storytelling and explaining the context in which this artwork was
made. Do we know how the artwork was used and how it was displayed?
Yet, we want to emphasize that although the 3D print might not be exactly accurate to
the original’s current or past state, it meets the inquiry central to this research
project
Currently, after recording the panel’s colors and topography, we are aiming to continue this research by processing the data. By researching the artwork’s materials (e.g. using dendrological research, IRR, MA-XRF scanning), damages, art historical past, and by relying on the knowledge of the restorer, we will analyze the digital model on its accuracy. This way, we can combine the digital data gathered by Factum Foundation with the knowledge of the professionals involved in the conservation to come to a digital model which most accurately presents the current and past state of the panel. We aim to explore how we can combine different modalities to learn more about the materials and stratigraphy of the panel. This could be used to study the effect of changes in material composition.
Consequently, multiple printed facsimiles of the artwork will be made to see the physical effects of digital changes made to the materials. Two 3D prints will be made by Factum Foundation in collaboration with the restorer of the painting, Caroline van der Elst. She will be involved with the digital restoration and will check the facsimiles to make the final material appearance correspond to what the panel originally must have looked like. Additionally, in collaboration with Canon Production Printing, we will try to create a third 3D printed facsimile without the post-printed craftsmanship (the retouchings of the restorer). This way, we aim to analyze both the digital model as well as the 3D printing technology’s ability to correctly reconstruct the material appearance of the panel. The 3D prints will be useful in communicating the dilemma to a larger audience (of both professionals and non-professionals) and will help in making the multifaceted authenticity of the artwork more clear during a potential exhibition about this project. Additionally, perception research done during this event and using the 3D prints will provide insight into the perception of the artwork and the potential effects of removing the background.
The two accurate 3D prints of Factum Foundation of both versions of the painting also allow the investigation of the perception of the artwork. An eye tracking experiment will be conducted to analyze the viewing experience of the visitor, regarding the two versions of the artwork. The eye tracking research will be combined with the think aloud-method, in which raw eye-tracking data is supported with qualitative data based on the conversations of the participants. We will focus on the effect of the light source (stable / unstable) on the perception of both versions of the painting. A hypothetical difference in perception is the appearance of the blood of Christ in the painting. Using an unstable light source (e.g. flickering candle-light), the contrast between the shine of the full golden background and the matte red tempera used for the blood could mean a better visibility and thus a stronger symbolic presence, in comparison to the current blue background. The perception research using the 3D prints will provide insight in the perception of the artwork and the potential effects of removing the background. This, together with the high quality of the reproductions, will be highly important for the final restoration of
This project is done in collaboration with Museum Catharijneconvent, Delft University of Technology, Leiden University, Utrecht University, and The Factum Foundation.
The authors would like to extend their sincere thanks to Carlos Bayod of the Factum Foundation for reviewing the technical information; Micha Leeflang as the representative of Museum Catharijneconvent; Caroline van der Elst for restoring this artwork; Clemens Weijkamp of Canon Production Printing for the elevated printing; Stichting Rembrandt, Leiden University Centre for the Arts in Society and LDE – Centre for Cultural Heritage and Development, The Netherlands Institute for Conservation+Art+Science+ for making this project possible.