Join Paul F. Aubin for an in-depth discussion in this video Creating domes, part of Revit: Tips, Tricks, and Troubleshooting.
- [Instructor] Today I want to talk to you about creating domes. Now, I'm going to create these as in-place roofs, but you could build them in the family editor as some other category, if you want. But one of the advantages of using an in-place family is you can actually choose the roof category. So to me, it seems pretty logical for these dome forms to be thought of as roofs, and I kind of want them categorized that way. Now there are some disadvantages to choosing in-place families. They can be a little bit heavier, it can perform a little bit slower, and you really can't copy them, but other than that it's a good choice for something like a dome.
I've kind of laid out some of the guidelines here to get us started just to kind of speed things up. What I have in this file is some grids that we're going to use as reference to kind of mark where the centers of all these domes are going to be. If we look at the roof plan, I've got another grid here called Grid A that I'm using as a work plane. And we'll talk about that one a little bit more in a few minutes. So, I'm going to work primarily in the south elevation, and I'll zoom in over here on the left on grid line one. These first two domes. I've got a full, half-round dome here, and then a shallower one here.
I'm going to create both of these the same way. The way you create an in-place family is to use the component button, and the dropdown on there gives you access to the Model In-Place tool. When this displays the dialogue you get to choose a category, and what's unique about in-place families is you can choose not only the standard, loadable categories but you can also choose system family categories as well, like the roofs category, or the floors, or walls, or ceilings. So, I'm going to call this one Dome One and click okay, and that puts me in my model edit mode here.
So, next I'm going to go to a revolve, and if you've ever created a revolve before you just draw sort of half the shape, and then you spin it around an axis. Since I've already got this line here to get us started, I'll use pick lines, and I'll just pick anywhere on that curve. Then I'm going to set the offset to whatever thickness I want the shell of the dome to have, so I'll just go with one foot here. Offset that down. Then I'll set this back to zero, switch to straight lines here, and just kind of cap that end off there, and cap this end off here.
So you want to create an enclosed shape, but notice I only need half of it, and that's because when we go to axis line, we can either do pick or draw, and I'm just going to draw an axis line like so. That blue dash line is what that shape will spin around, and when I click finish, it will create the dome form. Now, I'm going to click finish model, and that will complete our first dome, and then let's look at it in 3D right here, and you might be able to see it better if we switch to shading.
And then you can see we have that nice dome form. For a really simple kind of curved dome like that one or even this one, using a revolve can be the easiest way to go. So let's just do it again. Model In-Place. I'll choose roofs again. Click okay. Call this one Dome Two. Choose a revolve here. Pick the line. Set my offset. Draw a straight line. Put the offset back to zero.
Cap it off here. And here. I need to clean up that little corner or it won't work, and then draw an axis line down below and finish it. And finish the model. And then back in 3D. We now have that sort of shallower dome right there. So, there's two really simple dome forms that you can create using revolves. Now over here, you can see that I have a slightly different geometry laid out for the next one.
So, to create this sort of onion shaped dome, what I did was I went on Google, and I just searched for onion domes, and I came up with this image right here. And I chose this one just 'cause it had really nice contrast against the blue sky, so it made it easy to trace. If you recall, I pointed out to you that I had this grid line A in the floor plan. So what I did was I went to the set button here, and I chose grid line A as the work plane, and that allows me to draw these model lines, and all I did was go to Model Line, and start drawing with an arc, and kind of just pick a few points here, and kind of eyeball the curvature, and then do my arc continue there, and just kind of keep going around, and you can see that it's pretty easy to just sort of trace over that shape right there.
And just to save us some time, I've completed that shape here, and provided it for us already, but you're welcomed to trace over, and finish drawing it from there if you prefer. Now, the approach that we're going to take here is a little different. Instead of using a revolve, I'm going to use a sweep for this one. And the reason is we can choose this round path here, which is just a circle that I drew in plan. We can choose that as the sweep path, and then this as the profile to sweep.
To get started, I want to create another Model In-Place. One more roof. This time I'll just call it Onion Dome to be a little more descriptive. And this time I want a sweep. So, you can do Sketch Path and draw the circle. I'm going to do Pick Path since I've got it already, and I'll just pick right there. Now notice that it puts the Sketch Path perpendicular at a 90 degree angle to where I've drawn my shape. Now you can grab this thing and you can move it.
Now sometimes it's hard to do that in 3D, so I'm going to go to the roof plan view, and just kind of grab it here and drag, and you see how it kind of will flip over to the other direction and that just makes it easier because now it's parallel to the sketch that I've already drawn. I'm going to click finish here to finish the path of the sweep. Then, you do select profile next, and then edit profile right next to that. And now since I've drawn this already, I'm just going to use the pick option here, and just highlight one of these edges, press tab and then click.
And it should do it all the way around. Then I'll click finish. And it's kind of warning me that I don't have a closed loop here so let's see if we can see where the little gap is. It's not really highlighting it, but I think it's right there. So let me click continue. And sure enough, yeah. There's a little open gap right there. So let me grab that little endpoint and snap that together, and that should take care of it. 'Kay, that worked. And there we go. So now we have this beautiful onion shaped curve that sweeps all the way around.
You'll notice that there's a little open gap at the top. I did that on purpose because if you close it all the way so it's touching, the sweep will fail. It doesn't like to touch itself. So you've got to leave a little open gap there. You can just plug that in with an extrusion later. But here's the reason why I wanted to do the sweep. If you look at the original illustration, this was actually an eight sided dome. It's not a smooth round dome all the way around like that.
So you select a sweep. It's got a featured called Trajectory Segmentation, and when you have curved edges on your path like we do, you can use that feature. So all you have to do is check the box right here, and then the maximum segmentation angle will be listed there next. Now at 360 degrees, it's going to actually turn it into a square. Even though you had a circle, the maximum segmentation for the circle it goes to a square. Any angle that you pick between 360 and 90 is going to give a square.
So if I go as low as 90, I still get a square, but if I go a little lower than that like 75, that'll give me a hexagon. It'll do six sides. And if I go a little lower still, like maybe 45, I'm going to get an octagon. And if I keep going lower and lower, I'm going to get more and more sides. So if you want, you can actually go very low. 10 degrees, five degrees and end up with many, many sides. Now in our case, we wanted eight sides. So 45 will do the trick.
What's really nice about that Trajectory Segmentation feature is you can build this single continuous form. You don't have to create all the separate sides, and manually join them all together. It just takes care of everything for you just simply by sweeping this around a round path. I'll click finish here. And that gives us our final onion shaped dome. I've created one extra shape over here on the side that I'm going to let you play with, as it's sort of a challenge exercise.
I've given you a hint here by putting these references planes that if you want to use the Trajectory Segmentation option, the sweep option that we just talked about, you need to leave that little gap at the end, and plug it in later with an extrusion, but otherwise you can draw either of these two domes that we already did as a revolve using the sweep method. Just draw a round path on the floor for the path, and then draw your shape and sweep around it. If you leave Trajectory Segmentation turned off, it'll be smooth and if you turn it on, you'll get a faceted dome.
If ever you need to create any dome forms in your projects, then there's a few techniques that you can use, either revolves or sweeps within in-place roof families.
NOTE: The exercise files for this course can only be opened in the most recent version of Revit (Revit 2017).
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