Architectural_Design_with_SketchUp

Architectural Design with SketchUp
Accurate Modeling
The often-voiced notion that SketchUp is capable of merely “rough” and sketchy work is
quickly dispelled when we look at how the program stores numbers internally. For example,
querying the value of the mathematical constant pi using the internal scripting tools (covered
in detail in Chapter 6) gives us the number 3.14159265358979. As you can see, this number
is stored internally with precision to 15 digits. Any length or position value in SketchUp’s 3D
space is therefore internally stored with the same degree of precision.
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Independent of where you use SketchUp in the world and what your unit settings are,
length and coordinates are always stored internally as inches. These values are then
conveniently converted into your local unit format before they are displayed in the
Measurements Box (the box that is displayed at the bottom of your screen by default in
Windows) or anywhere else in the program.
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To take advantage of this level of precision, use any of these tools when you are modeling:
Object snapping—Like other CAD software, SketchUp offers a complete set of object
snaps. This allows you to snap to endpoints, midpoints, edges, circle centers, and other
locations. (See Figure 2.15.)
Figure 2.15: Object snapping while drawing a line on a box
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Length snapping—When modeling a line, for example, the mouse cursor snaps in increments
of length that you have preset in the Preferences dialog (e.g., at every 1/8g). You
can then simply click once the correct value has been reached, and the line will have the
exact length. (See Figure 2.16.)
Inferences—One of SketchUp’s main strengths is a very intuitive inferencing system. This
means that you can reference a point in 3D and model relative to it. To use this feature,
start a tool (e.g., a line) and then move around 3D space. Especially if you move parallel
to one of the axes (your “rubber band” line will change to the color of the axis), you
will occasionally see a dashed line and a temporary reference point shown as a dot to
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