Tessellated Modellers
Solid Modeling This describes a class of simplified boundary-representation modellers which approximate to curved faces by a number of plane faces. Since these modellers are restricted to plane faces and this implies that all the edges are linear and all the loops are closed polygons. This restriction considerably reduces the amount of calculation needed to display the output and so speeds things up. It also simplifies the calculation of intersections and the hidden- line or hidden-surface removal.
However there are penalties associated with this type of modeller. Some objects are very difficult to represent, a simple example of such an object is a ball or sphere. For this type of curved surface, the user has a choice between accepting a very poor approximation or increasing the number of plane facets to the point where all the earlier advantages are lost in the sheer volume of data generated.