Detection of degenerate normal vectors on parametric surfaces: Tangent cone approach Original Research Article

Normal vectors of a surface are essential in various geometry-related applications. Since a normal vector at a point on a parametric surface is computed by a cross product of two tangent vectors at the point, a regular parametric surface may possess a degenerate normal vector at a point when tangent vectors of the surface are linearly dependent at the point. This paper describes an algorithm which tests if a regular parametric surface does not possess such a degenerate normal vector.