Datasheet

14
Part I: Getting Started with SketchUp
Understanding the difference between
paper and clay
Three-dimensional modeling software comes in two basic flavors: solids and
surfaces. Figure 1-1 and the following points illustrate the difference:
Figure 1-1:
SketchUp
models are
hollow.
Surface models are hollow
Solid models are solid
✓ SketchUp is a surfaces modeler. Everything in SketchUp is basically
made up of thin (infinitely thin, actually) surfaces — dubbed faces. Even
things that look thick (like cinder-block walls) are actually hollow shells.
Making models in SketchUp is a lot like building things out of paper —
really, really thin paper.
Surface modelers like SketchUp are great for making models quickly
because all you really need to worry about is modeling what things look
like. That’s not to say that they’re less capable; it’s just that they’re pri-
marily intended for visualization.
✓ Using a solids modeler is more like working with clay. When you cut
a solid model in half, you create new surfaces where you cut; that’s
because objects are, well, solid. Programs like SolidWorks, formxZ, and
Autodesk Inventor create solid models.
People who make parts — like mechanical engineers and industrial
designers — tend to work with solid models because they can use
them to do some pretty precise calculations. Being able to calculate the
volume of an object means that you can figure how much it will weigh,
for example. Also, special machines can produce real-life prototypes
directly from a solid-model file. These prototypes are handy for seeing
how lots of little things are going to fit together.
An important point to reinforce here is that there’s no “best” type of model-
ing software. It all depends on three things: how you like to work, what you’re
modeling, and what you plan to do with your model when it’s done.
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