Tuesday, May 28, 2019


This is a post that was overtaken by events in Paris, and my detour into the Gothic. It’s intended as the first in a series dealing with classical elements based on spiral geometry.

My first image is a hand sketch to illustrate the challenge of representing some of the more elaborate decorative detail found on some classical buildings. My recent work on the Corinthian capital begins to address this.

Related to the Corinthian is the Composite order. The two blur into each other at times, but essentially, if you treat the volutes as scrolls from an Ionic capital, you are getting into composite territory.

Very often there is a portion of egg and dart moulding between the scrolls, and quite possibly only one row of Acanthus leaves, so that the scrolls remain prominent.

You could argue that the volutes in Corinthian capitals are abstracted from plant forms, whereas Ionic scrolls reference the animal kingdom. Goat horns are symbols of Aries, my own birth sign, for what it’s worth. Other examples include snail shells, and the curled-up posture that centipedes and armadillos assume under threat.

The brackets that often “support“ pediments over doors and windows are called consoles. This term has taken on new meanings in the digital age, perhaps via the intermediary of the “console desk” basically a table top supported by scrolls.

Soane favoured elongated versions with elliptical motifs replacing the inner part of the spiral. I chose to create a more conventional version, because I want to develop methods for spiral motifs that can be repeated in different situations.

I started with some analytical sketches that explored possible modelling approaches. These were useful mental exercises, but in practice I took a different direction.

the next step was to trace a spline. Again I began rather ambitiously and scaled back to something simpler. Nothing in this post is rocket science. Sometimes common sense and adaptability are more useful than virtuosity.

The virtue of a spline in Revit is in its ability to scale proportionally, simply by stretching the end points. The long term goal is to be able to create new versions of the console relatively easily. They don’t have to be  completely automated and parametric. I’m happy to open them up in family editor and do a bit of pushing and pulling. Just as long as I don’t have to start again from scratch every time.

The spline becomes a sweep, thin at first, then gradually thickened and simplified. Two copies of the sweep define the shape and the width of a console bracket.

This is embellished with a couple of extrusions and pick-edge sweeps to shape the connecting surfaces. A loaded profile allows for rapid development of different versions

And so we gradually home in on the design I originally selected. That’s about as far as I got. I’m sure that future demands will lead to multiple variants on this theme, but not perhaps on Project Notre Dame which seems destined to consume my “spare time”for the foreseeable future.

So to conclude this post, an atmospheric image courtesy of Enscape3d and PIXLR. If only there were more hours in the day.

Tuesday, May 14, 2019


An interesting weekend. I chose to confine myself mostly to the West End, so as to make room for other collaborators. What can you say about the Facade? The sheer scale, the balance of horizontal and vertical rhythms, the clarity of form despite the profusion of sculptural detail. 

I began by tackling the arches at the base of the Bell Towers. In contrast to the solidity of the stout round columns that march down the nave, these piers present themselves as sinuous clusters of parallel ribs.

Without a point cloud or a definitive set of survey drawings it’s sometimes difficult to know where to start and conflicts often arise. You just have to throw yourself into it, and make some bold decisions. This often means modelling “in-place” at first and gradually working out how to break it down into modular components.

As the day proceeded, Europe came online, and then USA. I saved my work, and we upgraded the model to Revit 2020, which went smoothly enough. The organ loft acts as a bridge between upper rooms in both towers. These are a couple of metres higher than the Triforium galleries, so you descend about it dozen steps to access these.

After making a quick placeholder for the wood and metal of the organ itself, I reached instinctively for Enscape3d, but it wasn’t there. I guess I need to upgrade now that I’m using 2020.

 Unsure whether my complementary license would stretch to that I reverted to the slower process of Revit’s own rendering engine plus a bit of jiggery-pokery with Photoshop. 

Well into Saturday by now, and time to move outside. Cornices to be added, and heights to be adjusted. We have an elevation that looks quite convincing, so I’m trusting that, pasted behind a semi-transparent working view. 

There are two rhythmic horizontal bands that tie the Facade together and divide it into three sections. The upper one is quite open and delicate. I realised for the first time that the central portion of this forms a double decker bridge between the Bell Towers.

The lower band is a continuous array of statues, twice life size, each standing in its own niche. I had previously created a very crude substitute for the upper band. Now I needed to rough out the “standing men” in their sentry boxes.   

I’m quite proud of my “lego person” : two extrusions, supporting a sweep, topped by a revolve.  Choosing appropriate Revit native geometry to represent complex sculptural objects in a simplified abstract way ranks as one of my favourite challenges.  How can you fool the brain to engage its automated object-recognition response?  If you can manage that, people will see far more than is actually there.

Sunday afternoon is always a tricky time. You can feel the modelling coming to an end, pressure building to prepare a blog post. I didn’t devote as much time as I should have to cleaning up the file and establishing naming standards.  But perhaps I can squeeze in one more item.

Don’t know how many intermediate floors there are in the towers. I made a guess, added an in-place extrusion to define the spiral stair void, placed some doors for access. All this based on a few lines on the ground floor plan.

So that’s it for another weekend. The Slack group is getting quite lively and people are starting to take on tasks. Personalities interacting across the continents. Next weekend I really must put some order into the naming conventions … if I can tear myself away from the excitement of the modelling challenges for long enough :)

Monday evening and trying to finish this post. Daniel Hurtubise exported an executables version of the model using Enscape3d and shared it with us. That’s the source of these last few images.   Walking (and flying) around this interactive model is a wonderful way to reflect on the shortcomings of the current model and prioritise tasks.  It's also a great way to deepen my appreciation of the architecture.  The model is in white mode, which focuses attention on the forms rather than the materials.  Lady in White?

Tuesday, May 7, 2019


I begin this weekend, intending to treat it as a concept design submission. The goal is to have half a dozen sheets of drawings (plans, elevations, sections) several perspective views and a tidied up model with a fairly consistent level of development across the whole building. Let’s see what happens.

Thursday evening found me sketching ideas for vault family strategies on my phone. I knew that the curved ambulatories around the East end would be tricky but I was optimistic.

Friday morning revealed serious issues with the existing setting out. This would have to be resolved before embarking on the vaults. First thing to do is look more carefully. Peel off another layer of the onion. There are radial alignments where the flying buttresses sit. These were not working.

Also there should be curved sections of wall between the arches of the outer row, not free standing columns like the two inner rings. I decided to use a new background image. Maybe this plan was more accurate. Certainly easier to read.

The next detour along my weekend journey was distracting but positive. Conversations with potential collaborators, which I managed to get moved to Slack eventually. Four way conversations in full swing by Saturday.

I realised that there was a double grid at the transition from straight to curved, an offset of about 1.5m This was crucial in getting the radial alignments to work.

Along the sides of the nave I have columns nested into the arch families. This works well, but around the curve the columns need to be independent in order to fine tune their position and alignment.

All this took time. The second pass through the model can be frustrating. Work proceeds more slowly than during the first roughing out. But the complexity of the apse Geometry is quite fascinating. I would love to compare with other cathedrals. I wonder if someone has done this already.

Here there are 5 bays in the inner ring, 10 in the middle ring, and 13 in the outer. The first two rings are evenly spaced. But the third has grouped arches. This allows for the thickness of the hefty walls that anchor the flying buttresses.

So on the outer edge you have vaults that link 3 arches on one side to two on the other. Creating a sort of zigzag pattern. This seemed like a suitable challenge for Saturday.

 I tried the swept blend approach that had worked well for the radial vaults high above the altar. Actually, these need to be reworked now because the offset has disturbed their regularity. The Leica TruView site was really helpful in visualising the context here.  It really captures the spirit of Gothic architecture: bundles of circular ribs curving upwards.  The tricky part of the Swept Blend in this situation is the way the void extrusion cuts at an oblique angle to the second profile. 

Couldn’t get the swept blend to work for the zigzag. Too much irregularity. Can’t get the ends of the vaults to match the arches. So I opted for Point World, and lofted surfaces. Took a long time and the fit is still far from perfect. But I learnt a lot about the subtlety of these spaces.  This is all manually created with an in-place mass.  You could thicken the surface up using wall/roof by surface, but I don’t think the junction at the ridges will work out too well.  The alternative would be to use a closed profile for the loft, instead of a line.

Looking from above you get a feel for the nature of the challenge.  There are five wedge shaped portions of vaulting between the zigzag of the ribs.  The middle one is symmetrical, but the others are skewed.  It’s just the way things work when you divide the space up like that.  You can see the small gaps down the sides where the vaults meet the ribs. 

Of course, it’s always possible to generate a softer image that disguises the minor imperfections that leave me dissatisfied with my efforts so far.  “Fake News” you may say, but I think it’s always useful to step back from time to time and view your work from a metaphorical distance.  Between the groups of 3 arches there is a wider section of wall.  The round column is pushed a little further forward and there is a flat splay leading back to the arch.  There should be a horizontal line where the vault meets this splay.  Not happening.  Something wrong with the geometry but I’m not sure how to fix it.

There are 3 types of zigzag vault. I’ve done one instance of the pink type. One out of three. There are two different types that connect two arches to one (green and blue) Looks like I’m going to pass all these on to Alfredo now. Big sigh of relief. 

Alfredo very generously offered to host the model on his BIM360 site.  Ideally I would have liked Autodesk to host the model, but those discussions have not yet come to a conclusion and there are several people keen to contribute, so we went ahead.  There will need to be discussions about how we coordinate our efforts.  From previous experience with Project Soane, a naming system for the various elements will be helpful, so that will probably be my initial focus next weekend.

After uploading the model on Sunday afternoon, I had time for a bit more modelling.  Some adjustments to the main vaults over the choir and the apse.  Not complete, but enough to establish how the double grid is accommodated.  Then I roughly sketched in the intermediate flying buttresses around the apse.  This is another example of a “3 bays into 2” situation.  So you get two buttresses converging to meet at their highest point.  I have made them straight in plan at present, but actually they need to do a bit of a “dog-leg”

So we have a lot of fascinating challenges, and a small team of experienced Reviteers.  Let’s see what happens over the next few weeks.

There's nothing like a good collaboration.