Sweeping Method:

In b-rep approach, a list of the faces, edges and vertices of the model together with the topological and adjacency relationships among them is kept. The topology is utilized to find out the set of edges which constitute the boundary of a particular face or which meet at a specific vertex. The designer may construct his model from drawing the several views of the object having the interconnecting lines among the views to establish their connectivity. This technique is depicted in Figure. To make a model which is symmetrical around an axis, a 2-D profile may be make and then spun (or swept) around an axis, as illustrated in Figure. A linear sweep of a surface, for instance, produced an 'extruded' part along with constant thickness.

A rotational sweep generates a 'turned' part along with axial symmetry.

Both methods (b-rep and c-rep) contain their relative advantages and disadvantages. In c-rep systems, it is comparatively easy to construct a topological correct and precise solid model from the available library of primitives. This is compact in storage requirements, but slow at generating pictures. Alternatively, a b-rep system gives the designer more freedom in building complicated models however the validity of the model could be destroyed in the procedure. It is also more costly on memory. Figure evaluated the steps taken to construct an object by using b-rep and c-rep approaches.