Dr. Lindsay Cook: “Restoring Notre-Dame: A Look at the Digital Scans That Could Help”

– Good afternoon everyone. Nice to see everybody
here on this sunny day. It’s incredible. I think it’s a tribute to
the topic and to our speaker. My name is Louisa Wood Ruby and I’m head of Research Department here at The Frick Art Reference Library. This is the ninth lecture of
our Digital Art History Lab, a virtual lab founded
in the library in 2014 to stimulate research and scholarship in the field of art history using the most recent
digital technologies. As more and more of
the library’s resources become available online, we’re committed to
finding new ways to access and share them with the wider public, all the while remaining cognizant that the digital world
can never fully replace the depth of resources available through our books and archives. On April 15th of this year, the world was shocked and dismayed by images of Notre-Dame on fire. Disbelief and pain were
the most common reactions. Were any people hurt? How bad was the damage? Did the rose windows survive, the art? Soon afterwards, there were
reports about the rebuilding. Could it be done? How? How long would it take? How much would it cost? It was then that we learned
about a digital project begun by the late Dr.
Andrew Tallon in 2010 to make a complete 3D laser
mapping of the cathedral. How wonderful, we thought, if we could see those
scans here at The Frick to highlight how the digital can be used to rescue the real world. Having had Dr. Tallon’s mentor Dr. Stephen Murray of Colombia
University here last year to speak about his work on
the Cathedral of Amiens, we knew that amazing images of this type are very interesting
and very good to look at and we tracked Lindsay Cook down to ask if she would like
to speak to us today. Thankfully, she agreed and I now have the pleasure
of introducing her. Dr. Lindsay Cook is
Visiting Assistant Professor of Art at Vassar College where she teaches Medieval
Art and Architecture. Her research focuses on the
intersection of architectural and institutional history
in the Middle Ages and the creation of the
image of Notre-Dame of Paris. She earned her BA in Art History in French from Vassar College and her MA, MPhil, and PhD from the Department of Art
History and Archeaology at Colombia University. In 2010 and ’11, she participated in two
successive field sessions of mapping gothic France, a multiyear digital humanities project envisioned by Stephen Murray, Andrew Tallon, and Rory O’Neill and supported by a major grant
from the Mellon Foundation. Lindsey took panoramic
photographs in Paris, the Ile-de-France, Burgundy, and Southwestern France for the project which aims to present
the spatial, temporal, and narrative dimensions
of gothic architecture. This invaluable cache of images is freely accessible to the
public at This coming spring, Penn State University Press will publish “Notre-Dame of Paris Through Time,” Lindsey’s English translation of the book first published in 2013 in French as “Notre-Dame de Paris:
Neuf siecles d’histoire” co-authored by Sorbonne Art
History Professor Dany Sondron and the late Vassar Art History
Professor Andrew Tallon. Lindsey is also in the process of revising for publication
her dissertation entitled “Architectural
Citation of Notre-Dame of Paris “in the Land of the
Paris Cathedral Chapter: “a Study of the Architectural
and Institutional Connections “Between the Cathedral of Paris “and Village Churches on
the City’s Periphery.” Please join me in welcoming Lindsey. (audience applauding) – Good afternoon everyone and thank you, Louisa, for your kind introduction and for inviting me to speak in the Digital Art History Lab. It is a privilege and a real pleasure to be
here at The Frick Collection and thank you all out
there for being here today to hear about the
conservation and restoration of Notre-Dame of Paris and the place of Andrew Tallon’s
laser scans in that effort. On that note, I am incredibly grateful particularly to Marie Tallon for giving me her
blessing to speak publicly about her late husband’s research since his untimely death
less than a year ago. In French, the verb (speaking
in foreign language), to disappear, is used to refer both to
an object that has vanished and more euphemistically
to a person who has died. So rather than (speaking
in foreign language), she died, a newspaper article
about the death of say, a famous actress might instead read (speaking in foreign language), literally, she disappeared, similar to the English
expression she passed away. My presentation today invokes
both senses of that term to chart the double disappearance that has led us to assemble
in this beautiful space today. The first sort of disappearance refers to the vanishing
of Notre-Dame of Paris as we all knew it. The details of this catastrophe, no doubt familiar to many
of you, bear repeating. On the evening of April 15th 2019, an alarm sounded during mass
at the Cathedral of Paris setting in motion the
evacuation of the public. Yet the priest carried on, eventually sending the
organist of all people to double check on the alarm. A series of miscommunications followed. The security employee on the clock was new and the arcane labeling
system on the alarm console led to the misinterpretation of the signal and initially seemed to
indicate a false alarm. And as a result, the fire department was not
called for about half an hour. By the time the fire fighters arrived, the blaze was roaring under
the gabled wooden roof. The fire fighters, familiar with the ins
and outs of the cathedral from the drills they had run to prepare for such a disaster at that very site entered the fray. Eventually, bolstering their efforts was a vast amount of water
pumped from the Seine. All of a sudden, the cathedral’s
position within the city surrounded by the river became more than a picturesque
accident of history. The lead covering of the
roof and spire melted. The wooden framework of
both roof and spire burned, splintered, and fell to pieces. While most of this debris fell
onto the tops of the vaults, the concentration of
material from the spire led it to break through
the central crossing vault and membranes of the other
vaults of the transept arm with molten lead likewise flowing forth into the central vessel
via these eerie apertures. But the fire did not stop there. It spread to the wooden belfry of the north tower of the main facade, so not actually the stone
tower that we’re seeing here but the belfry within it. At a certain point, the Paris Fire Brigade Commander General Jean-Claude Gallet made the decision to
give up on the main roof and concentrate on the
fire in the north tower. The fire fighters feared that if the belfry continued to burn, the fire would spread to the wooden belfry in the south tower, destroy the belfries in both, and transform the massive bronze bells suspended from these
internal wooden structures into careening projectiles. This approach was extremely effective. What’s even more astonishing
is that it succeeded without the death of a single
fire fighter or civilian. So at this point, I’m showing
you this image from the past taken in this case in 2010 in the context of the field session Louisa mentioned a moment ago of mapping gothic France. What was lost, of course, was the spire we’re seeing here, the roof here covered
in this lead covering, and the fire had at some
point spread into the belfry on the north tower. A fire is a fire is a fire and the sights live streamed
across the globe on April 15th such as this still from drone footage taken after the collapse of the spire paralleled medieval
descriptions of great fires from the time when Notre-Dame of Paris was under construction in the second half of the 12th century, of the 1174 fire at Canterbury Cathedral, the Chronicler Gervase wrote, quote, cinders and sparks carried
aloft by the high wind were deposited upon the church and being driven by the fury of the wind between the joints of the lead remained there amongst
the half rotten planks. And shortly glowing with increasing heat, set fire to the rotten rafters. From these, the fire was communicated to the larger beams and their braces. No one yet perceiving or helping. He’s again mentioning the disconnect between the building underneath and the wooden roof
above, hidden from view. He continues for the well
painted ceiling below and the sheet lead covering above, concealed between them, the fire that had arisen within. Meantime, the three cottages whence the mischief had
arisen being destroyed and the popular excitement
having subsided, everybody went home again while the neglected church was consuming with internal fire unknown to all. A very similar thing happened here. Gervase continues, but beams and braces burning, the flames rose to the slopes of the roof and the sheets of lead
yielded to the increasing heat and began to melt. Thus, the raging wind
finding a freer entrance increased the fury of the fire and to the flames beginning
to show themselves a cry arose in the church yard. See, see, the church is on fire. We all know where we were when we heard that Notre-Dame
was on fire in April. We can feel some empathy for the chronicler of the 12th century. By the morning of Tuesday April 16th, an assessment of the damage
could begin in earnest. Gone was the 13th century roof, its trusses composed of whole oak trees. Now, split and burnt to a crisp, they littered the crossing and choir and charged the tops of the vaults. So you’re seeing them here, some of them sort of
incinerated, covering, and actually starting to
weight down the vaults where they used to stand above them not connected to them at all. Gone was the 18th century spire, a product of the imagination of restoration architect Viollet-le-Duc who did tip his hat to the
cathedral’s medieval spire dismantled in the 18th century even if his spire design knowingly departed from the original in significant respects. Gone was the majority
of the crossing vault and some segments of the vault
webbing of the transept arms. So you’re seeing that here as well. The transept, the crossing here
underneath the scaffolding and the transept here, you can see gaping holes in vaults of the transept as well, yet much remained intact. The damage to the masonry certainly could have been
far worse than it was. Most of Notre-Dame’s stone skeleton, composed of piers, pointed
arches, and masonry vaults was weakened by the fire and
the water used to put it out, but not broken. And all of the monumental sculpture, decorative iron work, and
stained glass remained in place. The fire fighters affiliated
with the Musee du Louvre trained specifically
to rescue works of art and other precious objects even managed to recover
the relics and reliquaries, altar pieces, sanctuary carpets, and other ornaments and church furnishings
kept in the cathedral. Nevertheless, the fire did
distort the image of Notre-Dame. The cathedral as we have
always known it vanished. This brings us to the
disappearance of the other sort. The April 2009 disappearance
of the Notre-Dame we all knew shone a spotlight on the November 2018
disappearance of Andrew Tallon, the architectural historian, long time Vassar College
Art History Professor and my own undergraduate mentor. The fire transformed this personal loss suffered privately by
Tallon’s family, friends, colleagues, and students
into a public spectacle. Due in large part to one stray tweet, a narrative emerged in the news media shortly after the Notre-Dame
fire was extinguished that a laser scan made by Andrew Tallon would be helpful in the
restoration of the cathedral. To my mind, the absolute
certainty of the messengers that this data would definitely be useful to the architecte en chef of Notre-Dame initially rubbed me the wrong way. And the very idea that the
existence of a computer file could somehow soften the blow of the death of a promising scholar seemed somewhat ghoulish even. Yet, there is a kernel
of truth in this story and it is that kernel of truth I would like to unearth today. In 2010 with the financial backing of the producers of a documentary eventually broadcast on the European arts and culture television station Arte, I’m sure many of you are familiar with this wonderful channel, as (speaking in foreign
language) or Cathedrals Unveiled. And with technical
assistance from a company and several individual subcontractors, some of them you’re
seeing here in this image, Andrew Tallon used a laser scanner manufactured by Leica Geosystems to produce a full laser
scan of Notre-Dame of Paris from pavement to spire. In 2010, he returned with an even more
sophisticated laser scanner to scan the western
frontispiece specifically in order to capture its texture to a greater extent than ever before. Here, we see the result
of that 2012 laser scan, so you will have noticed, I think, as you came in and sat down that you weren’t looking at a photograph. It was more perfect, more regular, and just quite different
than the visual impression that a photograph makes to us. The laser scans began by placing a series of reflective targets on the surface of the building. Then, the laser scanner was placed in dozens of spots
throughout the cathedral to capture every nook and cranny. In a PBS Special called
Building the Great Cathedrals, this was broadcast though Nova, Andrew Tallon explained what came next in his characteristic way with a blend of technical language and a heavy dose of Midwestern charm that bordered on folksiness which I say very fondly as a
native Midwesterner myself. Quote, the laser scanner
sends a little laser beam out from its eye and it measures 1,000 times a second the distance between itself
and whatever it’s hitting. And so as it slowly pans across the wall, it’s shooting out this laser and taking a whole series of measurements which are then represented
in three dimensions as a series of X, Y, Z coordinates. Laser scanning is an efficient means of measuring an entire edifice, resulting in a mass of data
known as a point cloud. That data set may then be
sliced into smaller pieces and examined more closely using analytical software
such as Vectorworks, Cloud Caster, and Cyclone. You’re seeing an example
of a slice right here. And just to make it very
clear what we’re seeing, we’re seeing basically a bay. So we see a couple of flying buttresses and a slice of the building. So you can look in and see
bits and pieces of the roof, the covering of the roof as well, and it becomes particularly
apparent from this kind of angle the fact that the vaults
are really independent of the wooden roof above. So while they do bear down and exert force onto the outer walls, they’re not actually placed
on top of the vaults. This was something that
was I suppose remarkable for everyone to learn through the fire. It’s unfortunate that it took that for people to understand this much about medieval architecture. While this data from the
Notre-Dame laser scans has become a priceless record, digitally preserving the Cathedral in its state prior to the conflagration, Tallon’s own reasons for
employing this technology in 2010 and 2012 were entirely different. The primary reason he wanted a laser scan of Notre-Dame of Paris was to understand more fully
the nature of gothic structure and to pinpoint structural
anomalies in the cathedral. He was as interested in
this pursuit in irregularity as he was in regularity. The most significant result from this approach taken at Notre-Dame led Tallon to confirm
Stephen Murray’s hypothesis that single spanned flying
buttresses had been planned from the outset of
construction around 1160, not added after the fact as a reaction to structural concerns as some scholars had posited previously. For instance, in the hypothetical
graphic reconstruction published in (mumbles) 1997 monograph, the Cathedral’s upper walls appear unsupported entirely
by flying buttresses in the initial version
of the gothic building. So you’re seeing nothing supporting all of the superstructure here. According to this hypothesis, the flying buttresses were added later on in response to structural problems. If this hypothesis were correct, then we would expect the
upper walls of the choir to have moved to some extent, buckling in the middle and splaying out toward the top resulting from the
thrust of the high vaults before the flying buttresses were added. So we would expect movement particularly of this upper wall here if this part of the building
was unsupported in this way for quite a long time as this
reconstruction would suggest. On the contrary, the 2010 laser scan showed that the walls were
more or less perfectly straight or in plumb, and thus, must have been supported by some kind of flying
buttresses from the outset. That is, the distance between
the walls remains consistent whether that distance is
measured closer to the ground, so if we measured this distance across the building down here, or closer to the high vaults, so closer. This measurement is almost
exactly the same as this one. This finding suggests that flying buttresses
of one kind or another have always supported this
part of the cathedral, the east end, the part
that was built first. And Tallon happened to share the view with his teacher and mine, Stephen Murray, that the form of those buttresses always looked more or less
the way they do today. Some of Andrew Tallon’s
findings were published in the 2013 book he co-authored with Sorbonne Architectural
History Professor and Researcher Dany Sondron entitled “Notre-Dame de Paris:
Neuf siecles d’histoire.” A new slightly revised
French edition of this book was published mere days
after the 2019 fire. It’s a very publicly
easily accessible book and so it’s a real testament
to people’s interest in this building
immediately after the fire that it had to be reissued
very shortly thereafter. This coming spring as we heard earlier, Penn State University Press will publish my English translation of that latest French edition. Its provisional title as we heard is “Notre-Dame of Paris Through Time.” This cathedral was not a static monument. It transformed again and again over the decades and the centuries. The laser scans of 2010 and 2012 are at the very core of this book. For instance, the laser
scans served as the basis for the drafting of a new
ground plan of the cathedral in what would be fair to call the first accurate plan of the building. For generations, plans of Notre-Dame were tidied up or corrected to appear more regular than
the building actually is. In reality, the cathedral’s ground plan is far more idiosyncratic. Here for instance, we see a slice of the laser scan from the level of the high vaults. So you can actually see the
ribs here of the high vaults throughout forming across
throughout the building. And in this view, the plasticity of the vault
ribs is particularly apparent. So you’ll see that they have this sort of sinuous curve to them. They’re not X’s as you might see them on a more formal,
finished, tidied up plan. A slice capturing the lower vaults of the nave aisles and ambulatory was also needed to draft a new plan. The finished plan fused together the two cross sections
I have just showed you. So here, we’re seeing as you can see the cross section was
taken at a lower point, and so you’re seeing the covering these again the ribs of the outer aisles and all the way around the ambulatory, but no longer the high vaults because we’re at a slice that’s
lower than the high vaults. Nowhere is the cathedral’s
irregularity more visible in the resulting plan
than in the nave piers. Represented on the left side of this image of the ground plan as dark blue circles
inscribed within squares. So I’ll point them out to you. If you’re not familiar with looking at a ground
plan of a gothic cathedral, here we are. These are the piers I’m referring to. I invite you to select one
of these dark blue circles and use your imagination to project a straight line out from the center of one circle and all the way across the nave. Does your imaginary line hit the center of the blue circle at the
opposite end of the nave? Not quite, right? As you will have noticed, each pier of the south nave arcade is positioned slightly to the right or east of the corresponding pier on the north side of the nave. So these piers are all a bit to the right, a bit to the east of these piers here. Even more remarkable than
these idiosyncrasies, you start to wonder how
does this building stand up if it has this kind of disparities, right? Is the perfect regularity of the analogous supports in the choir. So we might also just be astonished that this building stood up in the 12th century in the first place, but look at how perfectly
these piers are oriented according to the position of these piers. So the east end is much more
regular than the west end and this suggests that something
was going on over here. It’s a reason to look again at this plan. The 3D laser scan may have
mapped this irregularity to a greater degree of
accuracy than ever before, but it is the kind of anomaly that was actually long visible inside the building with the naked eye if you knew to look for it. If you were to stand in the
central vessel of Notre-Dame with your back against a pier and look straight ahead, you would see not the
center of another pier as you would expect, but rather a void. Very scary to see that when
you’re standing in the building. Or else the edge of the opposite pier. The laser scan also
revealed more subtle shifts and this is particularly
true in this image. For instance, this 2012 scan
of the western frontispiece makes it clear that this
part of the building settled as it was constructed. Follow the lines or
string courses overhead and at the feet of the
monumental crowned figures positioned above the three main portals. So I’m talking about these
figures that you’re seeing here, the gallery of kings, and the lines that you’re
seeing below their feet and above their heads. So follow those lines. Scan the surface of the
building with your eyes from the right to left. Does this look to you like
a straight horizontal line? No. The line has a slight downward slope to it indicating that this massive
construction settled unevenly as the western frontispiece was built beginning around the
turn of the 13th century. You can imagine as the
masons were working, the cathedral is really, it’s sinking to one
side and was corrected. Judging by these examples, it is clear that the laser scan effectively captured what was there when the scan was made in 2010 and 2012. Moreover, the scan served as the basis for a whole series of
digital reconstructions, re-imagining historical
states of the building, published in Sondron and Tallon’s 2013 book
I mentioned earlier. The graphic designer Laurent (mumbles) rendered the hypothetical reconstructions, layering appropriate textures
on top of the laser scan data as if it were skin
stretched over a skeleton. As accurate as the measurements of the underlying structure are, these reconstructions also reflect specific scholarly points of view. For instance, in this
hypothetical reconstruction of the 1177 state of the cathedral, we find single span flying buttresses much like the ones rebuilt later on yet more simply ornamented. So this is a scholarly opinion that’s being rendered
in this reconstruction. Along the same lines, brightly colored paint
adorns the sculpted surfaces of the western frontispiece from the three portals
to the gallery of kings in this digital reconstruction of the 1245 state of Notre-Dame. And the space between the nave buttresses has been filled in, so we’re talking about these spaces here, transformed into a series of chapels. This rendering is also
conjectural in parts. For example, since few
traces of the 12th century Notre-Dame transept remain, the north transept facade visible here is based upon the facade of a late 12th century abbey church. So this facade here has
nothing to do with anything that scholars know about
Notre-Dame of Paris. This was completely taken
down in the 13th century and so in this case,
it’s very conjectural. Keep your eye on that very lateral facade as we flash forward to
around the year 1300. Here again, we find the cathedral in flux with gabled cladding affixed to the exterior envelope of the cathedral and lofty pinnacles reinforcing
the buttress uprights. So you now see the buttresses
have started to change. They’re more sort of prickly. You feel like you would be pricked if you were to pick up the
building with your hands. The overall look of these
hypothetical reconstructions raises questions about how
to represent conjecture and scholarly uncertainty in this kind of exercise
in the digital arena. Using a highly accurate 3D model as the canvas for such projections makes the result
convincing, seductive even, and utterly pleasing to look at, but it also imbues the whole with an aura, a kind of truth value they
were never intended to project. Together, these three hypothetical historical reconstructions and the accurate ground plan have, I hope, given you a clearer picture of some of the applications
Andrew Tallon envisioned for the laser scan during his lifetime. The Notre-Dame fire itself has brought to light new applications for the laser scan of Notre-Dame, originally gathered for
entirely different reasons. Here, we see a rendering of
the north transept facade from the 2010 scan. What new applications for this technology has the fire presented? With a margin of error
of only five millimeters, the scan is an incredibly accurate digital record of the cathedral
as it stood before the fire. In his chronicle of the blaze, “Dans les flammes de
Notre-Dame” published in June, journalist Sebastian Spitzer presents a blow by blow
of the emergency response. He specifically addresses
various technologies from pen and ink drawings to drones employed the night of the fire to monitor the efficacy of
the fire fighting efforts. Notably, Spitzer writes that
around 9:30 p.m. Paris time, dozens of targets were placed
on the western frontispiece and transept facades to enable crews to use
laser measuring devices to monitor the structural
stability of the cathedral, particularly its north transept facade which I’ve shown you
here in the earlier scan. This course of action the
very night of the fire signaled that first responders feared for the structure of Notre-Dame. These fears have not dissipated in the subsequent weeks and months. In early May once the dust had settled, the company Art Graphique & Patrimoine conducted a new complete
laser survey of Notre-Dame. The 2010 and 2012 scans therefore provide a snapshot of the
cathedral prior to the blaze. With this scan serving as the baseline, it could be compared to
the May 2019 laser scan to identify differences
between them before and after. These differences would indicate
movement in the building and pinpoint areas of structural concern. If this initial comparison were
to indicate areas of stress, additional laser surveys could also be conducted
periodically in the future to monitor the situation. Here, we see a post fire
photograph of this same zone that I showed you in the
laser scan a moment ago with the gable of the
north transept facade not enclosing a wooden
roof for the first time since it was added in
the mid 13th century. And this is really a cause for concern and also the fact that you
still have the presence of the steel scaffolding that was erected to undertake the restoration
efforts just months before. Monitoring the movement of surviving parts of the
cathedral is one thing, but what about the parts of the building that were lost entirely? As we know, the spire became engulfed in flames, its lead covering melted and its desiccated blackened wood core crashed through the crossing vault. The most dramatic
application of the laser scan would be for architecte en
chef Philippe Villeneuve to use the 2010 and 2012 scans in his designs for the restoration. A bill introduced in the
French Senate last spring and after several
revisions signed into law at the end of July by French
President Emmanuel Macron as law 2019-803 led several senators to
recommend adding language stipulating that the new cathedral must take the same form as the version that stood on the plaza
immediately before the fire. While this language did
not ultimately make it into the text of the law, Philippe Villeneuve the architect has indicated that he
will restore the spire (speaking in foreign
language), identically. Whether you are relieved by
this likely course of action or feel it is a missed
opportunity for innovation, it does present the intriguing possibility that the laser scan can be
helpful in this process. For the spire in particular, the laser scan could be of use. The utility of the laser
scan will be far more limited with respect to the
restoration of the roof. While the laser scan could be helpful in recreating the roof lines, so the general outline and that really actually does give a lot of the look
of the overall cathedral, the silhouette. The scan of the wooden roof trusses will be of less value to
the restoration effort as the new roof will
almost certainly be made of a material more fire proof than wood. It is worth recognizing that our conception of this cathedral and approaches to its
restoration and thoroughly modern and thus it is little wonder that modern technology might
be part of the solution. If a fire on the scale of the one that raged at Notre-Dame this year had occurred in the 12th
century rather than the 21st, the building would have been rebuilt more or less from the ground up as was the case at Canterbury
Cathedral after the 1174 fire and at Chartres Cathedral
after the 1194 fire there. And the buildings as we know them were the aftermath of these
important great conflagrations. The disappearance of part of
the structure at Notre-Dame is no more lamentable to us today than similar losses were
to people back then, but we put more stock than ever before in Notre-Dame’s value
as a historic structure more so than we do its
importance as a sacred site or its power as a symbol
for the city of Paris or the nation of France. Following the 1194 fire at Chartres, a contemporary miracle
account reports that quote, the inhabitants of Chartres, clerics as well as laypeople, whose homes and practically
all their furnishings the aforementioned fire had consumed all deplored the destruction of the church to such an extent that they made absolutely no
mention of their own losses. They considered as their chief misfortune or rather the totality of their misfortune the fact that they unhappy wretches in justice for their own sins had lost the palace of the blessed virgin, the special glory of the city, the showpiece of the entire region, the incomparable house
of prayer, end quote. Today, we tend to focus primarily on the loss of the medieval
roof, 19th century spire, as well as the loss of the
public access to the interior and the vast majority of the great plaza to the west of the church. As the conservation and
restoration of Notre-Dame unfolds, there are numerous ways
to follow this story and stay engaged with the
monuments of medieval France. First of all, I encourage
you to read more scholarship in addition to investigate journalism. This book, of course, is one short, accessible, beautifully
illustrated way to do this. But if you’re interested in a deeper dive, the scholarly articles in English about the structure and
geometry of Notre-Dame authored by Caroline
Bruzelius, Bill Clarke, Michael Davis, Stephen Murray, Marvin Trachtenberg, Stefan Rolf Lefering, and Christopher Wilson in the ’80s, ’90s, and 2000s are all essential. If you have French, a whole world of literature
will open up to you as will the website of the newly formed group
of international scholars known as Scientifiques Notre-Dame. The resources available there, completely free and open to the public are generally excellent
although not peer reviewed. So this is the URL that you’re seeing at
the top of the screen. Explore too some of the digital resources featuring documentation of
earlier states of Notre-Dame including the website
Mapping Gothic France, the new panorama tour of Notre-Dame mounted by the Media
Center for Art History at Columbia University which brings together lots of media related to the Cathedral of Paris largely coming from Mapping Gothic, but also from other sources. The recent Getty Iris feature
is also worth considering even if you won’t make it to the related Getty
exhibition in Los Angeles. And the Online Exhibition
of Historical Photographs presented by the Conway Library
of the Courtauld Institute demonstrates the changing
face of Notre-Dame since the invention of photography
in the mid 19th century. Perhaps most importantly, follow closely the conservation and restoration efforts themselves which will likely stretch
far into the future beyond the optimistic
estimate of five years initially promised by the
president of the republic. The morning after the fire, architectes en chef des
monuments historiques Philippe Villeneuve
identified the top priorities for stabilizing the structure to guarantee a safe and secure environment in which conservators and restorers may confidently intervene. At the top of this list was protecting the
building from the elements. The fire, as we know,
took place on a Monday and by Friday of that same week, a series of structured white tarps resembling a line of giant umbrellas already covered the tops of the vaults, keeping them dry. So you’re seeing them
poking out here a little bit and if you’ve been to the
cathedral since the fire, you’ll know that if you stand
at the east end for instance and take in more or less this view, you’ll be able to see them
sort of flapping in the wind if it’s a windy day. The next item on the architect’s list is to dismantle the scaffolding that had been put up around the spire for the restoration just getting underway when the fire broke out. So you’re seeing that here. This is new but this is old. And it burned and is
certainly a cause for concern if it were to start breaking and also charging the vaults even further. The final item on this list
is to secure the vaults. This effort is now well underway and will culminate in the
removal of the roof debris from the tops of the vaults. To make this precarious intervention, beams will be installed along
the width of the main vessel and workers will rappel
down from these beams to direct the cranes responsible
for lifting the debris and removing it from the
mortar coated stone vaults. This is a very elaborate task. It sounds like it will soon be underway. Teaching in Paris this past
summer on the left bank, I chose to live on the right bank specifically so that I would get to pass by the cathedral
on my morning commute. I made this housing decision
prior to the April fire hoping to see the building daily
to advance my own research. Instead, each day, I witness
the ever changing face of the urgent consolidation effort. In some cases, these stabilizing maneuvers
mirrored to a great extent the medieval construction of Notre-Dame. For instance, much of the
form work recently installed to cradle the flying buttresses resembles the form work
scholars believe was used to construct the great gothic cathedral in the 12th and 13th centuries and certainly to restore it in the 19th. So you’re seeing a bit
of that peeking out here. There are great wooden,
mostly wooden form works. On your next trip to Paris, take the time to get as close
as you can to Notre-Dame and check in on the
status of that project. And until it’s safe to go back inside, take the opportunity to visit
other gothic sites in France. As the late Art Historian
Michael Camille famously wrote in the oening pages of his
posthumously published book “The Gargoyles of Notre-Dame,” quote, there are many churches
dedicated to Notre-Dame but there is only one Notre-Dame de Paris, well, we know, but there are equally, if differently impressive monuments throughout the country
awaiting your visit. The cathedrals of Bourges, Chartres, Amiens, Beauvais, Clermont-Ferrand, all have something to offer. And more than ever, we must not take these hulking
structures for granted. That’s the lesson I’ve learned as someone who studies
Notre-Dame specifically. Finally, we might put this loss, this vanishing act in perspective. For quite some time after the fire, I agonized over the fact that Notre-Dame would
never again be the same until one sweltering August day, I found myself shoulder to
shoulder with hundreds of others ascending the steps of the Acropolis and passing through the
columns on the Propylaea and it dawned on me that few
people visit that sacred rock to see intact structures with the exception of a handful of disgruntled Trip Advisor reviewers, one of whom I can tell you referred to the Athenian Acropolis as quote an overrated construction site. Similarly, the draw of Notre-Dame of Paris was never primarily its completeness. We might all take some solace in the fact that the virtues of this
magnificent cathedral do remain even if they did not escape
the fire completely unscathed and are temporarily encased in steel, wrapped in unsightly plastic,
and stiffened by wood. Eventually, Notre-Dame’s
vaults will be repaired and its roof and spire
will be reconstructed. Some years from now, the cathedral will reopen to the public looking cleaner and newer, yes, but more or less like it did
before in all likelihood. And in the interim, we have the point cloud data, a precious digital record of
the Notre-Dame we all knew, a ghost of what was, and maybe even if needed, a template for the
cathedral of the future. Thank you. (audience applauding) – Thank you, Lindsey,
for that very thoughtful and for me anyway, moving presentation of Notre-Dame. I think now, we have quite
a bit of time for questions, and thoughts, and comments for everybody if anyone would like to
make one, some questions. – I was gonna make one comment that the symbolism of
the fire of Notre-Dame is perhaps the same symbolism as what befell the Twin
Towers here in New York vis-a-vis the national appreciation of those structures symbolically. I was also wondering, you know, given the treasure that Notre-Dame is, you know, there is a paint
called intumescent paint which you probably know of which we use in structures which stalls a fire for over two hours because a thin coat of
paint expands 50 times and will allow a 560 degree Celsius or 1,040 degree Fahrenheit to incur before a structure collapses and why with this kind of structure the exposing of the structure itself wasn’t attended to as
this national treasure with just a very thin coat of paint, I think 45 mLs, to stall to allow fire
departments to come in and attend to any potential damage that a structure might encounter. – I certainly think that
this is going to open up a whole round of debate particularly in the monument historique about what to do and
how to treat buildings who could easily have the
same thing befall them. And it’s really too bad that more precautions
weren’t taken in this case. All of the plans that we saw that had been published and put together, the sort of plan for this kind of event, they thought it was going to
take much longer to transpire and it went very quickly as we saw. – Thank you very much
for a illuminating talk. I have two questions. The first is until recently, we were reading that in fact, the entire edifice could still collapse so compromised was the limestone. Do you have any fresh information that may be the consolidation should give us a little comfort? – Something that is very alarming to me is the fact that they paused
these emergency efforts for a brief time when they were concerned
about the lead content that was emitted as the
roof burned, of course, as we know, and melted. And the fact that in spite of the lead, the emergency work had to resume, that’s very alarming to me. And I do know that there have been some sort of good signs from this. The initial sort of
tests that have been done that I just doubt that it
will collapse tomorrow, but there are still a lot of concerns particularly for the mortar. That’s where the greatest
concern is, the gravest concern. You said you had a second question. – I have a second question. You showed a number of
other cathedrals in France, but I wondered whether do you know whether the authorities in Paris are in fact pointing and trying to promote a cathedral built 20
years before Notre-Dame in Paris itself called Saint-Denis, one of the great cathedrals of France, and maybe get people to go and see that. – You know, in fact, they were really pushing Saint-Denis for a while just recently because there’s a
restoration project there that’s very controversial to actually reconstruct one of the towers that fell down. And so I think as far as I know, that restoration project is
still going to take place. It was already part especially with the challenges France has been facing lately, Saint-Denis has been a sort of target for the French government for a long time and for the cultural services in general. And I think Saint-Denis has for all of its symbolic resonance has always been on the
radar among the authorities. Whether that takes off
and whether people listen is another question entirely. The centrality of this cathedral is part of why we all know it, part of why 13 million
people went there last year. – I have a question. Can I ask a question? Do we know with complete
certainty the cause of that fire? Could it have been arson? – There was a police
investigation that was conducted and there was no sign that there was anything
untoward about the fire. They think it was either
an electrical short or simply a butt of a
cigarette that was left and that was the sort of final
word on that from the police. – You’ve talked about using the laser scan for reconstruction. – Mm-hmm. – Do you know if it’s currently being used to compare where the stones are now to help stabilize the building so that it doesn’t weaken and collapse? – I think that’s most likely to be the way that it’s used ultimately. Right now, they’re still
dismantling the scaffolding and the vaults, it’s more of an as things fall down, they’re making sure that
nothing more falls down. But once they get to the point where they’re really
analyzing stone by stone what is there and what was there before, is it in the same position
that it was before, that’s where the laser scan
would really come into play. The scan was already shared with the architecte en chef who preceded Philippe Villeneuve and so it may already be in the possession and the idea is also to
find a way to donate it specifically to the cathedral
as opposed to an individual so that well into the future, it can be used for this
restoration campaign. – I believe you said that the stained glass
was preserved or the fire, attempts of the fire man. Could you go into a little more detail? Has it been removed because
some of your pictures– – Yes, indeed. So maybe I can go back and show you. Do you see that it looks
as if there are Band-Aids or sort of plastic baggies covering all the clear story windows? So this is covering. There’s no longer any glass. This was 19th century glass that was here, but of course, 13th century and 19th century glass
in the rose windows. So here, you’re seeing all
of the 19th century glass from the clear story removed. You can see what I was saying about going back to the middle ages. There’s wooden form work that you now see, so a triangle in each oculus. It’s a really remarkable sight. And then they’ve been covered
with this plastic material over the surface to protect them. So they’ve been taken
down, but they’re safe. And the idea, yes, it’s amazing. There has been some idea that there is a bit of
microcracking potentially in the 13th century glass of the rose. I’m not a stained glass specialist, but that’s what glass
specialists have suggested. So that’s something certainly to monitor, but it looks like the kind
of thing that can be repaired and there will be obviously a careful conservation of the glass. Mm-hmm? – The vaults, I assume they were the stone. And my question is are they going to be
reconstructed also the same way from the restore them in
recuperated stones from the, because they fell down, or are they going to be using
new stones of the same kind, or it’s going to be new concrete, reinforced concrete using
the same shape and so on because in fact, the vault, it was not a structural element. It was the fire proofing
of the wood and roof. – So at the moment, part of what they are doing and if you have been to Paris, you will have seen this when
the gates happen to be open is that there are great
sheds collecting stones and other material from the building either as it falls or as they’ve cleaned it up after the fire and those are being cataloged. But the idea most likely especially for the stones
of the crossing vault I think is what you’re referring to, so the central crossing vault and perhaps also the transept vault– – And the arches, the arches. – Most likely, these things
will be restored with new stone, but of the same, the original, as close as you can get to the type of limestone
that was used initially. That’s largely because it suffered. Limestone does of course suffer from heat and water application. And so that’s at least in my experience, what I’ve seen in the
past of other projects, that’s most likely what will happen, but it’s not the primary focus yet. – Excuse me, and the structure of the roof itself, it will be in wood again? Or it will be in aluminum, or steel, or something like that
to prevent another fire? – It’s very unlikely
it will be made of wood and that’s why I don’t
think the laser scan will be particularly useful on that end, but that also has not been
decided one way or the other. There are precedents for using
materials other than wood in these kinds of reconstructions. So at Chartres, for instance, there’s a cast and forged iron roof that was already made in the 19th century. And also at Rennes is another good example where the architect for
particular reasons used concrete. We’ll see what happens here. I don’t know yet what they’ll use. – [Male Speaker] When
will the decision be made? – I don’t know. I wish I knew. – [Male Speaker] Thank you, thank you. – Thank you very much for an illuminating and a wonderful lecture, and thankfully, Notre-Dame de Paris will not disappear because of technology. Can you comment at all
on the Cathedral Rennes which is one of the places to see because it was tragically burned by the Germans during World War I along with many other
buildings of French patrimony and reconstructed over decades as I understand with American,
a lot of American help. So how was, could you just give a little
bit of how that was done? And when we go to Rennes now, is it really, you know, is it from photographs
that it was reconstructed? Thank you. – So while Rennes was damaged dramatically by the shelling during
the First World War, much of the sculpture was preserved. So much like we saw in this case, the roof was destroyed at Rennes. The vaults were also really damaged and then they were reconstructed. They were reconstructed from
all kinds of representations. So they didn’t have recourse
to digital scans, right? But they did have many different kinds of graphic representations of the building and also of course photography. So between those two things,
they were able to restore, in some cases, in original materials or as close as you could
get to them in limestone, and then as I mentioned in other cases, in modern materials as
for the roof for instance. It took about 20 years or so to do that and so I think that’s
something to keep in mind as we move ahead is a very careful restoration
should also take place here. There should be time to take
stock of all the debris, understand what is still there, what stones could be preserved even if they have to move to the Musee de Cluny for instance before moving ahead and
trying to clear things away as if it were just debris and rubble. – Thank you. Given your expertise and great passion for Notre-Dame de Paris, have the French reached
out to you in any way aside from the Mister Tallon, the Professor Tallon’s images? – I would say it’s very interesting because that was what
got picked up immediately was these images. That’s been most of how I’ve, that’s been the main reason
I’ve been contacted period for the last five months and it was actually quite
overwhelming at the beginning, just the sort of onslaught. On the other hand, I’m so sort of grateful to be able to carry on
his legacy at that front, but I do imagine that at some point, I’ll pivot and get back to my own research and it does still involve this building. And I also was in Paris
this summer teaching and doing my own research, so. But it is true that that’s where my
efforts have been focused for the last few months. So I specifically focus on this building and its impact on architecture around the time that it was built and that means over a
really long period of time sort of in the (mumbles). – I think I have this, sorry. Just two quick questions. One, I think Philippe asked you about the concerns about collapsing now, but one of the things I understood was that because of the water, it was not clear how the
walls would be affected or might be affected
as the seasons changed. Do you know anything about this? I know there are concerns
now about turning cold. – Yes. In any case in any building and especially a historic structure, the freeze thaw cycle is worrisome. And so I think part of this has to do with the reason we know that Notre-Dame wasn’t going
to fall down any other year was because it had done
it the year before. And so with this new change, of course, the heat of the (mumbles) a few months ago was of great concern. That was when the campaign
had to be paused briefly and then was resumed, but it all has to do with sort
of contracting and expanding. – [Male Speaker] So we
just are gonna have to see. – We’re going to have to see. – The other question was you
mentioned the senate bill, but of course, the senate doesn’t have the
authority to stop Macron. So as we currently understand it, there’s still that decision, right, that there’s an architectural competition and the competition will be
decided ultimately by Macron or whoever, right? – So the person who at this point really seems to be on the site and in charge is the architecte en chef. So as much as there is this sort of ministry of
culture response to all of this, what’s happening on the ground so far has not been any different really from, except its sort of scale and the visibility of this campaign, from other restoration projects. And so we will see. It will be remarkable though
if he did sort of intervene and say no, you’re not going
to do what you want to do and instead we’ll do
what we’re going to do. – [Male Speaker] I didn’t mean so much what they would be allowed to do, but whether or not the idea
of doing something modern and not reconstructing Viollet’s
thing was going to prevail. – I doubt it, I really doubt it.
– Just based on? – Based on again, precedence. So in the cases of all of these cases, we saw new very modern roofs, new materials used in the roof which is under wraps and not visible. That’s what we’ve seen in the past. In general, this sort
of group of architects tends to be relatively
conservative, traditional, and I just suspect that it unless there were a real sort
of power play from above, it’s very unlikely that we’ll be seeing a
(mumbles) Notre-Dame. – [Male Speaker] I certainly
agree with you, but we’ll see. – I have two quick questions as well. I have read a couple of months ago that they were considering putting a whole dome over the cathedral to protect it from the vagaries of weather and changes in temperature. Has that plan been abandoned? – As far as I know, it hasn’t. So I was checking in to what Philippe
Villeneuve has been saying about what he’s done since April and he was mostly talking about this temporary structure that’s in place. I think once the scaffolding that was there for the previous
restoration is dismantled, that will open up new questions of what to do with this
gaping hole in the crossing. And that could be done
in many different ways, but I’m not sure that it’s determined that it will be a dome
or take any other form. – And the other question I had too was that I also read despite
promises of great funding from great billionaires, that the money has only been trickling in to repair the cathedral. Is that true? Has that changed? – If anyone works in development, you may know that there’s a
difference between a pledge and cash in hand. And that’s what’s happened. I mean, so a couple of these cases are, a great, vast quantity of the money, about 2/3 of the money
was to come from two, as you know, two important and fervent
Catholic billionaires. And while those were pledges, I don’t think they’re going to renege and not give their money. So we’ll see what happens. I do think that the concern, the narrative was oh, Notre-Dame has more money than it could ever know what
to do with and we’ll see. I mean, keep your eye out. Make sure this actually is true. We do want it to be preserved. Yes? – Just the wooden form
infill on the buttresses, can you talk a little bit about
what that was responding to? Was there some movement? – So what they’re worried about is when they remove the debris, the wooden debris especially
from the tops of the vaults, they’re worried about
what that’s going to do. And if potentially the
vaults start to press outward or if they even lost something there, they don’t want the buttresses. They are worried about
the vaults falling down. That’s the short answer. And if they were to do so, they don’t want the
buttresses to be pushing in and acting that way on the building, laterally inward on the building. Actually, Philippe Villeneuve
put this beautifully. There’s a video that you
can all go and look at. If you know French, you’ll
enjoy it a lot I think. They’ve just presented about what they’ve been
doing at the cathedral lately and this is essentially the way he puts it is to transform the buttresses into walls to neutralize the force, exactly, yes. – Given all the concerns
that have been brought up, do you and other scholars that may be involved with this project actually think it will be
finished in five years? – I doubt it. I think again, using precedents of other– – In your considered opinion, how long off the top of your head, how long– – More than a decade, more than a decade. I think it’s again just to
look at what’s happened before and the degree, the extent of the damage, and the centrality of this building, of course, there will be efforts to do it as quickly as possible, but also it needs to be done
in a considered fashion. I think it will take a while. Completely speculation, by the way. – How do you imagine that the cost, the financial cost of the restitution will impact the current
restitution of other churches such as Saint-Germain-des-Pres
and (mumbles). – I do think that this will
funnel funds to this project and take away from others. And as someone who works
very often on buildings that are off the beaten path, it is a little bit disconcerting. That said, there is one
of the four organizations that was considered the place where you were supposed to send your money right after the fire, the Fondation du patrimoine, they shifted, they pivoted, and once they thought they had plenty of money for Notre-Dame, they shifted to a campaign
that was more general called Plus Jamais Ca. And the idea is for other
structures throughout the country that could be allocated later
on without being earmarked specifically for Notre-Dame of Paris. So there is a desire to sort
of harness this interest and channel it in other directions. – I have another question
for you, if I may. When you showed the slide which the spire which is Viollet-le-Duc, you indicated they wanted to
restore it exactly as it was. As it turns out, we do have a 15th century
representation by (mumbles)– – Of course, yes. – Of exactly what it looked like proportionately slightly
smaller in the original. Why can’t they go back to the (mumbles) and do it the right way? – Interesting. So it could. The question is which
time of the cathedral do we want to restore to? And I think part of this comes from, there was an interesting book published, a sort of pamphlet almost. There have been many. It’s been an age of
pamphleteering this summer about Notre-Dame of Paris. And there’s this Sorbonne Professor, (mumbles), and he writes about. He didn’t know it was up for debate the 19th century part of the building. He thinks that that has become, he’s a 19th centuriest. This makes a lot of sense, right? But he doesn’t believe that
there’s any question about this and I think it is more of
a question we must ask. Of course, it would be possible. You’re right. We know what the spire, the
medieval spire looked like. But particularly for those who work in the Monument historique, they feel themselves in a lineage that began in many ways
with Viollet-le-Duc and I feel like this is now part of French cultural heritage as well. – I just wanted to make one more comment. This is a very interesting photograph. We’ve been talking about detail. You know, structure
and roofs and what not. It was interesting just
to look at this detail, this elevation in terms of scale as this major, major, major
object in space, you know? And think of Saint Patrick’s
Cathedral down the road here. This building is 420
feet long, Notre-Dame. Saint Patrick’s, 332 feet. This one is 157 feet wide. Saint Patrick’s, 174. The spire is I think about the same, maybe 30 feet difference. So imaging walking down Fifth Avenue and seeing this object in space like we do see this thing here and realize the scale and
importance of that object which happens to be a building which affects everybody in and out, using it or walking around. It’s quite a remarkable photograph to bring that scale into reality. – And imagine everything being
cleared away on Fifth Avenue so you could see Saint
Patrick’s even better, right? I think it’s true that the way that this is really a jewel in the city with low structures, low slung
structures all around it, it does really stick out. Its monumentality is still just
as striking as it ever was. – I have an additional
question if you don’t mind. I’m an architect and I received a lot of emails and so on regarding (mumbles) news. And some months ago, I received the news about finally the decision has been made about the restoration of the Notre-Dame. And to my recollection, it
was a Korean team that– – I think I know what
you’re talking about. Was it potentially the public? There was a public design competition. So there were many professional
architects, of course, and the winners, I think it was three women architects who work for Skidmore,
Owings & Merrill in Chicago, my hometown. And they won this design competition, but it was a people’s competition. It was a vote that you
could do on the internet. It doesn’t have any sort of standing in the world of this restoration. – So it was not a legal one? It was not an official one?
– It was not, no. It’s very interesting also. I bought the book, so you can buy the book if you want to see all
50 of these projects and the winners did have, there were interesting ideas in them. So I think it’s interesting
to consider what, is this the best architects could do? What would be the best architects could do to respond to this structure? It’s an interesting question, but I don’t think it will
have really an impact on the actual shape of
Notre-Dame of Paris. – Well, that scheme was
more or less the same, restoring it more or less the same, but a larger spire that also
included some digital displays. – Yes. – Besides getting more light
in the middle of the church, also had all these digital displays. – And the hole in glass, yes.
– Yeah, correct, yeah. But it’s not official? This is just the– – The unofficial Notre-Dame
design competition. – Thank you so much. You enthusiasm is spectacular for those of us who knew little. Thank you. (audience applauding) However, all of the other cathedrals, the gothic churches, is this a bellwether? Should they also be scanned? I mean, you know, you’re speaking. I am not from here, but I am extraordinary in
love with Saint John Divine. – Yes, yes. – I mean, should that be
scanned for the future? Should Saint Pat’s? I mean, how do you approach
that from your position? Thank you.
– I think, absolutely, I hope that this
has demonstrated the value and I think it has also particularly I mentioned this company
Art Graphique & Patrimoine. They were the ones that went and took a laser scan shortly
after the fire at Notre-Dame. And I think they’ll see this
not only as an opportunity, an intellectual opportunity, but even potentially a
financial opportunity and an insurance opportunity to take scans of other
buildings in France. And certainly we should follow suit with the historic structures
that we care about. I think at the very least, having these images is so valuable even if it doesn’t end up impacting what you do in the future. The idea that you can have a
digital record of any building that we do value this much
is yes, we should do that. Andrew Tallon had done many other scans, so it was not just Notre-Dame of Paris. And other people have as well. So this is certainly an interest in medieval architectural studies, but I think now, it’s entered into other domains as well. – I don’t mean to deescalate
the tone of this conversation, but I’m sure that some of you are familiar or you probably are familiar with. I saw it on the internet right after this awful event happened. The video game. I certainly have never played
a video game in my life, but for the month of April, you were allowed to download
this video game for free which took you through all of Notre-Dame. Are you familiar with that? – Yes, so it was in, actually, at this point, I mean the scan is actually relatively old I suppose you could say, but so is the video game. So a relatively old video
game called Assassin’s Creed. I asked my brother about this and he said, “Why are you asking me about
this ancient video game?” And yes, it does, as many video games do. This is also something that in fact, I work with some students who this is probably
what they’ll end up doing is recreating architectural
worlds in video games. The difference between,
if you’re wondering, what’s the difference between
that and this laser scan, the laser scan is much more accurate. It’s down to a level of accuracy that the video game never
was supposed to achieve. So it’s a beautiful image. It allows you to move
around, to walk around. There are many things to recommend it, but in terms of its use for
this kind of technical purpose, it wouldn’t have as much validity. – Other questions? Anybody else for a last thought
or question for Lindsay? All right, going once. (laughing) Okay, well thank you very much again. – Thank you all. (audience applauding)

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