3. Geometric modeling

3.1 Model families

The geometric model is at the heart of the CAD/CAM system. It contains all the geometric information about the objects. The power of a CAD/CAM system depends to a large extent on the quality (or qualities) of its geometric model. Although this model is still insufficient, it is essential to understand the advantages and disadvantages of each family.

• Two-dimensional (2D) models

  These models are limited in their knowledge of objects to planar views, with no relationship, except for special tools, between them. They remain important today only because they are useful for the construction of 3D objects (sketches...) and because they serve as a basis for part of the dimensioning process, even if...