.3D modelling, also known as surface development and construction, is a process that is used to create 3D CAD models directly from measurement data with little or no additional design documentation.

Modelling can be done from design specifications starting with nothing but a blank screen or from digitized or scanned data. By digitizing items that have insufficient design documentation or require CAD data for modern manufacturing methods, a component can be quickly and accurately re-engineered.

What kinds of 3D modelling are there?

Essentially there are two types of modelling:

• Solid Modelling and
• Surface Modelling

Surface modelling concerns itself with the definition of complex shapes. To fully define such complex geometry often Nurbs (Non Uniform Rational B-Spline) surfaces are required. These mathematical surfaces allow a great deal of flexibility when the need to describe free-form organic shapes arises.

Most parts manufactured with tooling require some kind of Nurbs surface to support production. Reverse engineering is heavily dependent on Nurbs surfaces to transform captured digitized points into surfaces.

Solid modelling on the other hand is useful when building primitive geometry. Primitive geometry consists of basic surfaces such as planes, cylinders, cones, and spheres.

Solid modelling is much faster than surface modelling for simple shapes but generally speaking not capable of defining free form objects effectively or creating sophisticated features such as a fillets.