NURBS

Short for Non-Uniform Rational B-Spline, a mathematical representation of a 3-dimensional object. Most CAD/CAM applications support NURBS, which can be used to represent analytic shapes, such as cones, as well as free-form shapes, such as car bodies. NURBS are not used much for RT3D because they create a large number of polygons, but it is an available modeling method in some artist 3D packages.