- When you hide an edge between two faces, SketchUp treats those faces as though your edge is still there — it just doesn’t show the edge. Materials you’ve applied to each face stay separate, and each face is lit separately by SketchUp’s sun. The latter fact is the reason why simply hiding the edges between faces that are supposed to represent a smooth curve doesn’t make things look smooth — you still end up with a faceted look, as you can see in the second cylinder.
- When you smooth an edge between two faces, you’re telling SketchUp to treat them as a single face — with a single material and smooth-looking shading. The difference is pretty huge, as you can see in the third cylinder below.
- Use the Eraser. To smooth edges with the Eraser tool, hold down the Ctrl key (Option on the Mac) while you click or drag over the edges you want to smooth.
- Use the Soften Edges panel. Located on the Window menu, this panel lets you smooth a bunch of selected edges all at once, according to the angle of their adjacent faces. To get started: Select the edges you want to smooth and then move the slider to the right until you like the way your model looks.
- Choose View → Hidden Geometry so that the Hidden Geometry menu option is selected.
This makes hidden edges visible.
- Select the edges you want to unsmooth.
- In the Soften Edges panel, move the slider all the way to the left.
