Hidden Geometry

SketchUp lets you adjust the number of edges composing arcs and circles. When first activating an Arc or Circle tool (simply click it), the Value Control Box will display Sides. The default number of sides for an arc is 12, and the default for circles is 24. This means that any drawn arc or circle—no matter the length, orientation, or size—will be composed of 12 or 24 facets (Fig. 11-1) unless you change the default.

Fig. 11-1: Edges composing the arcs and circles.

The default value can be adjusted to increase or decrease the number of sides. More sides make smoother and rounder curves. However, more facets can make it more difficult to include components. This is explained in detail in the “Components and Faceted Surfaces” section.

For the Courthouse tutorial, just make sure that arcs and circles are set to their default values of 12 and 24 sides. The tutorial model cannot be constructed properly if you use other values.

Extruded 3D faces originating from arcs or circle edges are constructed of faceted faces. The number of faceted faces is equal to the number of sides that compose the arc or circle.

To set the dashed edges that compose the curvature to be visible (Fig. 11-2), turn on Hidden Geometry (View > Hidden Geometry). This will allow each individual face to be selected and adjusted (Fig. 11-3).