Getting to know Intersect with Model

Posted by Aidan Chopra, Product Evangelist

Back before we had a blog, we'd include Tips & Tricks in the SketchUpdate e-newsletter we sent (and still send) around every so often. Recently, it occurred to me that some folks might find it useful to have them in a more "readily-bookmarkable" form; namely, this blog. The following tips originally ran in the August 2006 edition of the SketchUpdate.

Ever heard of Intersect with Model? If you haven't, don't feel bad; we did a pretty good job of hiding one of the most powerful modeling tools in SketchUp. We sometimes hide things to make SketchUp easier to learn (figuring out software is tricky when eighty buttons are screaming for your attention). Intersect with Model is a tool that automatically adds edges defined by faces that intersect in your model.

Basic:

Let's say you have a cube and a cylinder, and they overlap. If you look carefully, there are no edges (lines) where the surfaces of the two figures meet. If you select them both and then right-click, then choose Intersect with Model in the menu that pops up, edges will be created wherever the cube and the cylinder overlap. You can then erase any edges you don't want. This technique is integral to more advanced modeling in SketchUp, and it's really impressive -- Bryce once used Intersect with Model to get a date with a particularly enthusiastic SketchUp user at an AIA event in Los Angeles. For a much clearer explanation of this feature, check out this SketchUp model in the 3D Warehouse.

Intermediate:

Eventually, you'll need to cut a window in a curved surface. Since Push/Pull doesn't work on faces that aren't flat, Intersect with Model is the tool to use. The key is to create an object that's the size and shape of the opening you want, position it where you want the opening, then use Intersect with Model and the Eraser to create the necessary geometry. The tricky part (for most people) is positioning the opening-sized object in exactly the right spot. Here's a model that demonstrates a method for making the process easier.

Advanced:

In one of the rare architecture history classes through which I didn't sleep (I feel bad about it now, okay?), I learned that four pendentives are what you get when you try to stick a dome on top of a square space. They're the sort-of-triangular sections of a sphere that occur in each of the four corners where the drum supporting the dome sits on top of four arches. I think pendentives are neat, so I began to think about how I might model them easily in SketchUp. Using Intersect with Model, I figured out a method that works pretty well, I think.

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