Non-uniform Quadratic B-spline Subdivision Non-uniform Biquadratic B-spline Surfaces +2 P+1 P+1+1 +1 -1 t-1 P-1J-1 d-1 d +1 1 +1 A horizonal knot interval di and a vertical knot interval e;is assigned to each control point Pi as each control point corresponds to a biquadratic surface patch. ZHuang.G Wang Non-Uniform Recursive Doo-Sabin Surfaces (NURDSes) Non-uniform Quadratic B-spline Subdivision Non-uniform Biquadratic B-spline Surfaces A horizonal knot interval di and a vertical knot interval ej is assigned to each control point Pi,j , as each control point corresponds to a biquadratic surface patch. Z Huang, G Wang Non-Uniform Recursive Doo-Sabin Surfaces (NURDSes)