Quadratic NURSSes Generalization of non-uniform biquadratic B-spline surfaces to meshes of arbitrary topology [Sederberg et al.1998]. No closed form limit point rules. Converge for n-sided faces with n<12,but may diverge if n 12 [Qin et al.1998]. Z Huang.G Wang Non-Uniform Recursive Doo-Sabin Surtaces (NURDSes) Quadratic NURSSes Generalization of non-uniform biquadratic B-spline surfaces to meshes of arbitrary topology [Sederberg et al. 1998]. No closed form limit point rules. Converge for n-sided faces with n ≤ 12, but may diverge if n > 12 [Qin et al. 1998]. Z Huang, G Wang Non-Uniform Recursive Doo-Sabin Surfaces (NURDSes)