2.1.3 Constructive Solid Geometries

Constructive solid geometry (CSG) is a geometry representation, where basic shapes, like cubes or spheres, are used together with set operations to represent a geometry [38]. Commonly supported set operations are set intersection, set union, and set difference as visualized in Figure 2.5. The basic shapes and the set operations are used to form a hierarchical CSG tree. An example of a CSG tree for a geometry is shown in Figure 2.6. CSG representations also support multi-region geometries, if a CSG tree is created for every region.

Figure 2.5: CSG set operations of two sets

Figure 2.6: CSG tree, image by Zottie

A cube, a sphere, and a cylinder are used as basic shapes and are combined with union, intersection, and set difference operations.