Modeling some fancy architectural/structural columns in SketchUp! Come hang out with us!!
2020-04-17T18:00:00Z
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A thorough treatment of the various orders can be found here:
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Are you going to do entasis? It will be interesting to watch how you combine that with fluting!
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Awesome! Thanks, Nathaniel!
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Trying to combine fluting with the entasis is what stopped me cold. The easy solution (cop out) was to represent the fluting with a carefully crafted material/texture. Even this was not a perfect solution, since the texture towards the top of the column tended to get a little wonky. I’m not saying it can’t be done but it is more difficult than one would think at first glance.
The ratio of the fluting to the unfluted surface (ionic, corinthian, composite) on the column needs to be maintained, the entire height of the column, I think I am correct on this. As the diameter of the column decreases (entasis) this causes the diameter of the fluting indentation to also decrease as well as follow along the curved path of the columns surface. The boolean solid required to create the fluting would not only need to follow the curve of the entasis but also be a lofted extrusion itself, in order to be dimensionally correct.
I’ve attached my textures/images for the doric and ionic fluting below for those interested. Surprisingly the illusion actually works quite well when applied to the column shaft:
For this texture method to work correctly one must set the texture image width equal to the chord length (ie. 24 chords or segments in the circle, or 20 in the case of a Doric column). This dimension can easily be measured directly from the model or calculated given the number of segments and the column diameter.
I know how I’d do that but then I’ve done it before. I’m also interested to see how Aaron does it.
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Aaron did a good job with the entasis and fluting, and with the rest of the modeling of the capitals and bases, I was impressed. Scaling the top of the column after first creating the fluting was something I hadn’t really considered.
However, to get it perfectly correct the entasis should follow a tangent arc. How would one scale the column to achieve this? I’m assuming there is a plugin which would allow one to do this sort of non-linear scaling (or lofting), I don’t know I’m still stumped.
Another reason why I finally opted not to actually model the fluting was due to the high poly count contributed by said fluting. One of the primary goals of my plugins is to maintain as low a poly count as possible.
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On the live chat, I kept trying to say that the very top curve. part of the astragal, was an ogee curve like this:
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Exactly, the chord length is equal to the radius of the fluting. At first glance the little equilateral triangle scribed in dashed lines does not seem to convey this information, but at a second look it’s there.
Agreed, Aaron drew it with a cove but who’s keeping score. I similarly posted something to the effect that it was a Cyma reversa with a fillet which is essentially the same as an ogee, but I wasn’t going to press the issue any further and thereby slow down the modeling and presentation.
Overall, it was one of my favorite live modeling sessions to date.
For the few of us who care, my references say that “ogee” is the generic term for a double-curve profile with a convex arc and a concave arc that meet at a point of inflection. “Cyma” is usually combined with either “recta” or “reversa” to indicate whether the convex curve is at the bottom (“cyma recta”) or at the top (“cyma reversa”). So here, as @medeek said, we have a cyma reversa form of ogee.
In the enlarged drawing @john_mcclenahan attached, it appears that the two curves are tangent on a sloping line rather than vertical (in a cyma recta with equal radius arcs) or horizontal (cyma reversa). That could result if their centers were offset to allow for the small flat at the bottom.
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Howdy Aaron, Thanks for the Great video and Forum post! The YouTube video of this is missing the first 20 minutes or so. Any chance it can be fixed? Also, I am going to try to post my smoothing plane model. Should I start a new post for it or post on the Live Q & A in Forums? Cheers, Stephen Stewart
Hey thanks, Cymas or ogres are used a lot in wood mounlding profiles too. Cheers, Steve
Hahahahahahah! Beastly spell check is to blame I am sure!
Another piece of trivia: “Roman ogee” generally refers to one made using two equal-radius circular arcs. Evidently the Greeks preferred ellipses over circles.
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A rather beastly version?
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