Sunday, April 7, 2019


Apparently the ubiquitous “egg & dart” motif was inspired by the Greek fighting formation or “phalanx”. That’s one theory anyway, implying that those ‘eggs’ are really ‘shields’. Certainly there are Greek vases that use rows of soldiers as rhythmic decorative elements. Actually this reminds me of the Guilloche also.

I do think the connection between vase painting and architectural ornament is worth pursuing. But we have a race to run, so let’s move on.

Like many other elements in classical design, what appears to be a simple formulaic device turns out to be capable of much variety. So I started out by reviewing the versions in my archive.  The differences may be quite subtle, but when you look carefully, almost every example takes a slightly different approach.

During my third pumpkin adventure I veered off into the animal kingdom, feeling that I had already “done vegetables “.  Along the way I developed a family that I called “the universal egg “

The core feature is a revolve, using two quarter ellipses that share a common radius. Imagine a globe whose equator is set by this shared radius. The northern hemisphere then has its own radius so it can be made rather flat, or more pointed. Similar rules apply  to the southern hemisphere.  Now you could set these three radii one by one, but I prefer to set Slenderness,” “Eccentricity” & “Width”. In other words, you have two parameters to define the shape of the egg, and a third to scale that shape up and down.

The egg is hollow (although it doesn’t need to be for the current purpose) This is achieved by having a smaller ‘void egg’, inside the solid one, and adding a parameter for ‘Thickness’ of the shell. We also have an ‘Undercut’ parameter to shave a slice off the bottom and give it a flat base.

The result is a family that can assume a wide variety of shapes and proportions, each of which can then be scaled to whatever size you like.  If the slenderness and Eccentricity are both set to 1, you will have a sphere.  Give it an undercut of 0.5 and you have a hemisphere.  Low slenderness values will give you a relatively flat disk.  Slenderness of 2 will be something like a rugby ball.

The eggs sit in a nest, hollowed out from an ovolo moulding (ie a sweep).  The nest has sloping sides, so that means a void blend. A second blend cuts away the space between two nests. In this case it leaves a solid sliver in the middle of the gap. (the dart)

In other cases, a separate component is used to place arrow heads in the gaps. So by duplicating and adapting my first attempt, I created two more versions of the egg and dart pattern.   Eventually I will nest these as arrays into line-based families, or as balusters in “railings,” using the “double-nested planting hack” to scale the geometry to suit project needs.

But right now I want to tackle another theme commonly used in classical ornament.

Some of these examples look similar to the egg and dart, but closer inspection reveals that they are all based on plant leaves. This time the range of variations is much greater.

My first example is based on wood carving technique. Almost 50 years ago a friend of mine demonstrated how this is done with a few deft strokes of a gouge, cutting away a series of crescent shaped chips. Very impressive.

As the variations mount up, you can see the advantage of using a nested dart component which can easily be adapted to new situations, gradually building up a library of mix and match modular items.

The possibilities are almost endless, as a second set of images from my archive illustrate. Some are simple and highly stylised. Others present a more elaborate, organic impression.  There is a fascinating tension between abstraction and a more faithful representation of reality: a tension that eventually gave birth to modern art.

I’m not going to explain all my modelling efforts in detail. If you are interested in this kind of thing, then half the fascination lies in developing your own strategies. I will just present one more that uses a ‘sweep and cookie cutter’ approach. There are two sweeps, one with an offset profile for the recessed surface effect.

And here is a nice YouTube link I found on carving egg & dart mouldings in wood.


This is the first blog post where I have assembled the images on my phone. I normally spend half of my weekend working in Revit and taking snapshots of my progress along the way. To weave these into a story involves grouping two or three images together and annotating them. I like my readers to be able to get the main gist of my message visually.  The narrative is an optional bonus.

I’ve been using Pixlr to process digital sketches for a while, but had been ignoring the collage function, which turns out to have a really neat touch interface. So now I can take a break from mouse & keyboard to create most of my text and images on the phone.  Friday morning lie-ins suddenly became productive as well as a way of relaxing after a busy week in my day job.

That’s a shot from the One Drive folder for this post. Of course, it’s accessible from all my devices.  The cloud is great for enabling fluid and intuitive work flows that link workstation grade machines to touch-screen phones and tablets.  Seems like the human touch is coming back into my work in all kinds of ways.

I’m going to finish with a screen grab of Pixlr adding text to a snapshot of Pixlr assembling a collage. Worlds within worlds, very “Alice” (and Humpty Dumpty)


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