B-rep

B-rep or boundary representation is a method for representing shapes using the limits. A solid is represented as a collection of connected surface elements, showing the boundary between solid and non-solid.

CSG

CSG or Constructive Solid Geometry is a technique used in solid modeling. CSG allows a modeler to create a complex surface or object by using Boolean operations to combine simpler objects.

Boolean operations on sets

Union:

Intersection:

Difference:

Extrusion

Sweeping is allowing a two-dimensional planar cross section to sweep through space.

Revolved extrusion

A revolved extrusion or a solid of revolution is a solid object that is obtained by rotating a plane cross section around a straight line (the axis) that lies on the same plane.

Arbitrary profiles

In addition to parameterized profiles, there is a free profile shape type called arbitrary profiles. These profiles are defined by an ifcCurve, which may have linear and curved segments. Thin wall profiles can be defined by a centerline and a thickness. Other profiles are defined by a closed shape. Closed profile shape may or may not have inner voids.

Parameterized profiles

There are several parameterized profiles available in the IFC specification. Those include standard hot-rolled steel I, L, T, U, and Z profiles, cold formed C profiles, and generic rectangle and circle profiles with or without a hollow. These profiles are defined with their parameters, such as width, height, web thickness and flange thickness.