This chapter contains an overview of geometry and its use in CAD modelling. There are two types of geometry, analytic and numeric. With analytic geometry the form is explicit and controlled by a few parameters. With numeric geometry the shape is controlled by a set of points, called control points, and the geometric forms are general. Often CAD systems use a mixture, with analytic geometry for a few common forms and numeric geometry for all the rest. The numeric geometry is important for covering all special shapes The chapter explains some basic techniques and common operations used as well as some exercises for using numerical geometry.
KeywordsControl Point Surface Patch NURBS Curve Control Polygon Geometric Entity
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