Computer Aided Design (CAD) Key Terms

Learn some of the key terms that relate to CAD

By Emmet McMahan

CAD uses computers to design objects that may be real or imaginary. This commonly refers to the construction of shapes, but also includes essential symbolic information such as materials, tolerances and manufacturing procedures. CAD can design two-dimensional lines and curves, as well as three-dimensional curves, solids and surfaces. CAD is an important industry that has a range of practical applications including computer animation, mechanical engineering and product container design. CAD also has theoretical applications, such as research in computational geometry and differential geometry.

ACIS

ACIS is a three-dimensional modelling technology that forms the kernel for a variety of CAD programs, such as AutoCAD. It is a trademarked name rather than an acronym, but is commonly believed to come from the phrase "Andy, Charles, Ian's System."
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Vector

The mathematical definition of a vector refers to any line segment in space. In the context of a CAD application, however, the term vector is broadened to include any object which is constructed of vectors.
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CAD object

A CAD object uses coordinate data to represent an object. It is useful in applications that do not require an exact description because is has a free-form topology.
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Facet

A facet in the context of a CAD application refers to any triangle-shaped element. Its most common use is to approximate a three-dimensional surface, which may require many facets for a complex surface.
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Axis

An axis is an imaginary line segment that provides a basis for measurement for a CAD model. The complete Cartesian coordinate system in three-dimensional spaces includes an x, y and z axis.
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Reference object

A reference object is a real object that serves as a model for the CAD object. A manufacturer may subsequently compare the specifications of manufactured objects to the reference object.
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