Sunday, August 9, 2020


A couple of weeks ago The Revit Kid (aka Jeff Pinheiro) got in touch and asked me to appear on his podcast “BIM after dark” to showcase the Notre Dame model.  The podcast took place on Thursday night.


I probably should practice looking at the screen while I think.  Seems like my eyes skew “up and away” when I’m thinking 😊.  Also note the face masks and the Zimbabwe flag decorating the back wall of my apartment.

In preparation for this session I put some time into annotating and organizing the sheet set to tell a story.  The grid studies sheet was already there.  I just added some explanatory text.  How many weekends did I sped puzzling through the reference material, comparing measurements and deciding whether to adjust the model to a new grid?  It went through at least 3 iterations, if I remember right, but we now have something that reflects the size of each bay quite closely, and maintains the basic relationships, but keeps the setting out orthogonal.

This sheet serves as a record of how that works.

Alfredo made a very nice cutaway “view” for his AU session last year, and I have updated this with a few annotations.  It serves well as an introductory sheet.  It was created by placing three views on a sheet and carefully adjusting their section boxes.  You have to place the views in the right order to get them to “overlap” convincingly.  “Send to back” only works with 2d elements.

The upper floor plan.  I love the way this sheet has turned out.  It has developed slowly over the months.  The elevations were added to set up “tasks” based on starter families.  The windows were tagged with their family names, and those families placed in a series of folders along with reference images.  Francois has risen to the challenge of developing these elements, and made excellent progress, though not yet complete. So the windows are now tagged with codes (Type Mark) which refer back to a window types sheet (Legend)

While preparing for this talk, I added some notes and photos so that this sheet now gives a splendid overview of the Tribune Galleries, and of the strengthening works around the crossing by VLD.  I puzzled over the reason for those non-standard bays, from the time we first started the model.  At one time I had decided it was a device to disguise the much wider bay between grids 8 & 9.  The full sequence of events and structural logic has only dawned on me in the past couple of weeks. 


At this point, I took my first detour into family editor.  These small flights of steps occur in two places at the ends of the Tribune Galleries.  In a way they are like a straightened out spiral stair.  But they are also precursors of the “cantilever stair” which became so common in the domestic architecture of Europe from Renaissance times until quite recently.  More accurately called a “torsion stair” each stone tread is supported on 3 of its corners: two embedded in the wall, and the third resting on the step below.

I do love making items like this in Family Editor.  Nothing fancy, just extrusions and a couple of parameters … one level of nesting.  But it’s a wonderful way to understand something that catches my eye in the work of builders past.


I’m rather proud of the next sheet, which combines a large central perspective view with smaller plans and sections, plus a couple of small internal camera shots.  This serves to illustrate some complex spatial relationships relating to an enlargement of the clerestory windows that was undertaken almost as soon as the original design was complete.  The story is further complicated by changes that were made by Viollet-le-Duc in the nineteenth century: strengthening the crossing to take the weight of his new spire.

For me, this sheet exemplifies the discovery process that takes place on a collaborative historical investigation like Project Notre Dame.  Week-by-week we gradually tease out a story that spans several centuries of human experience.

Segue to the vaults sheet, by noting those vaults on the previous sheet that are higher on the outside face.  This is a feature of ribbed gothic vaults that I had not been aware of before modelling Notre Dame.  Now, of course, I see it everywhere when I visit old cathedrals.  Alfredo took the adaptive route (what I call “Point World”) and I took a quick look at his 8-point vault, used in the Bell towers.  By way of contrast, I then opened up my attempt to use the traditional family editor to create a flexible 4-part vault with the ability to cover rectangular bays of different sizes, and to selectively lift the outer arches on any of the four sides. 

There are pros and cons to both approaches of course, and I think there is still room for improvement in the way we are representing the vaults.  That applies to most aspects of the model actually.

Jeff passed on a couple of questions from the chat, but I didn’t get to read through the comments till next day.  Interesting feedback. 

On the right you can see drawings by VLD explaining a method for constructing the vault infill between the arched ribs.  Fascinating to me as a former bricklayer.


I decided to add jpegs to the elevation sheets. In the process I noticed, for the first time, that we have two old photos taken from a similar angle, one just before VLD restored the spire, and one shortly after.  Looking closely at these, the changes he made to the windows around the crossing are very clear, also the addition of clock faces, and the small stone pyramids capping the spiral stairs.

West End Story … a study sheet for the West End with its Bell Towers and King’s Gallery.  The levels are quite tricky … some tweaking of View Range parameters required.  Assembly of this sheet was the final stage in a long process of understanding how these various spaces fit together; the galleries, balconies and passages that link them together.

Last of the Family Editor detours, featuring the double-nested planting hack and imported mesh geometry with hidden edges.

Alfredo had started to set up a sheet for the Rose windows. I adjusted the scales and added a strip on the right-hand edge.  Legend views of Marc Zappia’s contributions, a couple of notes and one of VLD’s fantastic drawings.

I managed to squeeze in a quick tour of the model in Enscape3d.  For speed I had exported and Enscape executable and had it open in the background.  Imagine a world before Enscape! 

I didn’t have time to show all the sheets.  The sections are not quite complete but starting tell their stories quite nicely.  But I think we covered enough ground for one session.  Clearly there is a lot of potential interest out there in the kind of work we are doing.  The power of “the BIM pencil” to support curious minds in their attempts to enquire more deeply into our built history.

So once more, thanks to Jeff for setting this up and being such a genial host.  I don’t think I have a future career as a YouTube star, but perhaps I could do a couple more of these kinds of live tours.  Notre Dame has more secrets to offer, and we could always go on to explore Project Soane.

If you have made it so far, I can offer you a small reward.  Follow the link to download a PDF copy of the current sheet set.  Far from final, but worth a look, I think.


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