State about the Computer-aided design

Computer-aided design (CAD), high-quality character fonts, data plots, and artists' sketches all contain smooth curves and surfaces. The path of a camera or object in an animation sequence is almost always smooth.

The need to represent curves and surfaces arises in two cases :

(i)  modeling existing objects (like a car, a face, a mountain, a toy etc.);

(ii)   modeling "from scratch" (so-called image synthesis), where no physical object is existing and the same is to be modelled.