Primitives of b-rep Scheme:

The building blocks for b-rep. models are following:

Vertex

This is a unique point (an ordered triplet) in space.

Edge

It is a finite, non-self-intersecting, directed space curve bounded through two vertices that are not necessarily distinct.

Face

It is defined as a finite associated, non-self-intersecting, region of a closed oriented surface bounded by one or more loops.

Loop

It is an ordered alternating sequence of vertices & edges.

Genus

This is the topological name for number of handles or from holes in an object.

Body (or Shell)

This is a set of faces that bound a single associated closed volume. A minimum body is a point. Topologically this body contain one face, one vertex, and no edges. This is called a seminal or singular body.

There are two kind of information in a b-rep: topological & geometric. Topological information gives the relationships among the edges, vertices and faces similar to that utilized in a wire-frame model. Additionally to connectivity, topological information also includes orientation of edges & faces. Geometric information is generally equations of the edges and faces.