Sunday, August 18, 2019


I’m about to go on vacation. Weekends will be spent with my grandsons, but on weekdays I will be wearing my “The Way We Build” hat. From 26-30 August I will be in London, looking at buildings and meeting people. The following week I will be based in South Yorkshire and from 9-13 Sept, somewhere between Hastings and Basingstoke. I am particularly interested in meeting people involved in Heritage Work and stone masonry.

I want to connect with people who can contribute practical insights into our work, which applies Building Information Modelling to the study of historic architecture. We are an international team of enthusiasts, using digital tools to ask probing questions about structures like Notre Dame de Paris.

How were the zigzag vaults around the ambulatory built? Why do the spiral stairs at the four corners of the Transepts terminate are different levels?   We intend to embed information in the model and to make it accessible online. Input from people with deep knowledge of traditional building crafts will be crucial. 

BIM is all about collaboration: bringing together multi-disciplinary teams and integrating their contributions. We are applying this approach to study how societies have chosen to build, in different times and places. 

Prior to starting Project Notre Dame, we spent 4 years piecing together a Revit model of the Bank of England, as it was when John Soane retired almost 200 years ago. 

I’ve always been a visual thinker. From as young as I can remember, drawing was my favourite way of analysing the world. I still use hand sketching as a way to gain fresh insights.  The fluid and intuitive nature of this hand-eye-brain process makes it a wonderful complement to the more constrained and systematic work of building a BIM model.


I love using the power of my “BIM pencil” to think about buildings. It forces you to think about function, structure and sequence in a way that simple mesh modelling (digital cardboard) fails to do. This is what we are doing on Project Notre Dame: taking lessons learned on Project Soane & using BIM to explore the “Way We Build”.


The term BIM is a catch-all label for digital tools and processes that facilitate collaborative thinking about buildings.  BIM uses data-rich models, to integrate contributions from multiple participants in a central location, where conflicts and queries can be discussed and resolved. We can create arresting visuals & VR experiences from the same data set we use to generate measured drawings, spreadsheets and analytics.

BIM is normally confined to commercial building contracts, but we believe that it has enormous potential for collaborative studies.  Almost everyone is fascinated by the way different human civilisations around the world have built towns and cities over the centuries. Increasingly people are applying BIM tools and processes to heritage work, archeology, art history, interpretative studies aimed at the general public.

BIM models have the potential to integrate contributions from a wide range of participants interested in understanding how buildings work, why they were built that way, what meaning they can convey to us today. This is the approach we aim to pioneer, drawing on the knowledge and experience of people across the world with a diverse range of skills and interests.

Our team of enthusiasts is spread across 4 continents, connected by cloud technologies. We learn by doing, by debating, by studying history. Mostly we are BIM addicts, but why not expand the circle?

If you have a different perspective to offer please contact me here on my blog, or through LinkedIn. Maybe we can meet in the UK and talk about buildings. What could be better? 

Kudos to Paul, Alfredo, Daniel, Marcel, Francois, Russell, Eugene and everyone else who has contributed work, images, ideas that are reflected in this post.

Tuesday, August 13, 2019


The triforium galleries on the chancel side (east of the crossing)  Circular windows above ogival recesses on the outside.  These were already in place along the sides (N&S) but not where the galleries turn the corner up against the transepts.  This reveals the need to omit the lower arches on the last flying buttresses, which lie in the plane of the outer wall.  Maybe a visibility switch would do the trick.

So while I’m here, might as well add the door that leads to a spiral stair (presumably)  And while I’m at it there are a couple of doors on the outside that connect via short balustraded galleries to the “bridge” that crosses the Rose Window.  This arrangement seems to be specific to the North transept.  The connections on the South side surely exist, but are not expressed on the outside of the building.  Why the difference?  Good question.

That spiral stair also connects to the roof over the Triforium Galleries.  Not stair object at present, just an open shaft.  The bridge across the rose has two levels, both accessed via short external balconies.  Piecing the story together bit by bit.  

Switching to the outside.  A while back I replaced the extrusion representing the Sacristy in the site context file and modelled a simplified version with actual walls and roofs in the main file, adjusting the windows etc where it connects to the cathedral.  I decided to do a similar job on the other building along the south side.  Was this a Bishop’s House?  I thought I read that somewhere.  The only reference I can see on the plans we have calls it a “Batiment du Personnel”  Also did a few small improvements to the Site Context file while I was at it. 

Then we got into a discussion on Slack about the trees (planting families)  I have been using a customized version of the standard RPC objects.  They render up nicely in Enscape, but if you want to do a shaded view from high level looking down on the building they look a bit naff.  

Realistic looks even worse from high up because they are just jpegs pasted on a vertical plane.  One answer is to use Enscape Assets.  These are Revit families and render nicely in Enscape.  In shaded views they have a low poly mesh.  Kind of a shapeless blob.  

A third option is to use a cad mesh tree with a finer level of detail, embedded in a Revit family in place of the Enscape geometry.  Two custom parameters refer Enscape to the appropriate Asset definition.  I have developed a system for embedding plan symbols that you can swap out and also scale relative to the height of the geometry so that it is roughly the same size in plan as the tree geometry itself.  So that’s what we are using at the moment.

Back to the triforium gallery, and looking at the curved portion around the apse, or ambulatory.  I’m not going to tackle the vaults.  (Alfredo territory) but I am going to have a look at the ribs that support the vaults and the way they site on clusters of columnettes that sit against the walls.  

If I can establish this relationship, at least in principle, it may help Alfredo when he gets a chance to take the “zig-zag” vaults to the next level of development.  The vaults he developed for the ground floor ambulatory are might impressive, but the way they connect to the arches and columns that support them is not yet fully resolved.  

Slack is an integral part of our workflow: constant chatter across the continents.  At first there were a couple of grumbles from those more familiar with WhatsApp.  I use WhatsApp all the time for friends and family, but for work groups collaborating on projects, Slack is a better tool.  Anyway, there was a call to change the Icon from the default “PN”  

I wanted to use Quasimodo, but Icons need to be bold and simple, so in the end I chose the West Rose.

Sunday, August 4, 2019


You can go on about data as much as you like, we are a visual and social species. We care what things look like and we like to look good for other people. Solving problems is never a purely rational exercise, so even though this is another “BIM geek” post about the nuts & bolts of Project Notre Dame, I’m starting with an image about creating sexy visuals by combining exported views in photoshop.

Pausing to create images with visual appeal is a regular part of my work process. Stand back and reflect, “turn the picture upside down”, think about the “why” questions. Ironically the tree is masking one of the most interesting “aha moments” arising from recent work. But I’m getting ahead of myself.

I have been taking Railing types created by Francois in the Mega Cloud and integrating them into the main model. More than 60 people have volunteered to contribute to Project Notre Dame, of these, about a third have accepted the invitation to the Mega Cloud that we are using to package up tasks and make reference material available. I have added a placeholder post the 3 Railing types Francois has created so far. Someone else can develop this further.

While placing these parapet railings (stone balustrades really) around the North side of the chancel, I noticed some seemingly random changes in level (A & B) Oddly enough the sill levels of the windows also change, but at the next bay along. Difficult to discern reasons here but maybe something will eventually emerge to cast further light.

I notice these things because I’m constantly scanning through reference photos, and something else caught my eye. There are further clues to the access routes I speculated about some weeks ago.

There is a red door on this facade. I’m guessing that there used to be a cloister on this side. The street is called Rue de la Cloitre, so it’s not much of a guess. The monks must have slipped through this door to attend evensong.

I duplicated the window family to create a placeholder version of the red door which one of our volunteers can take further. Raise your metaphorical hands in the Excel file provided.

So now we come to the big “AHA!“ moment. Long ago I noticed that the Triforium galleries turned the corner where they meet the Transepts. A little later I noticed that the roof pops up to a higher level where this occurs on the south side. I speculated that this was an innovation introduced by Violet le Duc. Not so. It seems that the lower roof between the two higher ends is the “innovation” and it dates back to the 13th century.

This is described in a pamphlet written by le Duc to explain his restoration strategy. He even considered reverting to the original treatment with smaller windows and a band of plain wall internally. The end bay next to the Bell Towers reflects this original configuration.

Another pause to create an artist’s impression. The metal railings along the street surely belong to modern times, but they help to provide scale and contrast to the huge mass of stone that is Our Lady of Paris.

Another placeholder family, and another puzzle. Why was this extra weight needed on the side of one buttress? And why does it only occur on one side of the building?  I love these kinds of questions, and I love the process of gradually getting to know your way around a complex building with a deep history.  Soane’s Bank of England was complex in a different way from Notre Dame: a maze of passageways and rooms of different shapes and sizes.  On the face of it a cathedral is a single, contiguous space but the access system is fascinating, the stone vaults are more varied than I could have imagined, and … who knows what else?

I have placed a couple of Enscape3d executables in the Tasks folder to help our content creators see the bigger picture within which they are playing a vital role. They don’t include the updates to the site model that I made towards the end of the weekend but they will be updated on a regular basis.

If you have a VR headset, use this to view the model. It’s an awesome experience. Thanks to the guys from Iris VR for advice and assistance in this regard. See you all next time.