All these problems can be avoided if a method of direct raytracing NURBS surfaces is used. The problem, which arises here, is complexity of deterministic solutions for nding the nearest intersection point between a ray and a NURBS surface. Although the exact intersection is difcult or even impossible to obtain, especially for higher order surfaces, an approximate solution can be obtained using numerical procedures. Many different approaches for nding an approximate solution have been proposed [Lischinski and Gonczarowski 1990; Wang et al. 2000; Martin et al. 2000], which are mostly based on two methods: Newton's iteration method [Toth 1985] and B´ezier clipping method [Nishita et al. 1990].