Creating 3-D Solid Models:

Two basic approaches to create solid models are :

  i.      Constructive solid geometry (CSG or c-rep), and

  ii.      Boundary representation (b-rep).

In CSG, the designer constructs the model fundamental solid primitives such like blocks, cones, cylinders, spheres, tubes and hexahedra in combination along with Boolean operations such like addition, subtraction, union and intersection. A complex model may be constructed in a building block manner, by combining the shapes or subtracting them from each other. Figure illustrated the various Boolean operations by using the different primitives, in constructing a solid model. An alternative name for the CSG method, set-theoritic modeling, occurs from the way in which primitives are combined by using the operators of set theory.