This paper presents an algorithm for optimal multi-degree reduction of rational disk Bézier curve in the L norm. We start by introducing a novel disk rational Bézier based on parallel projection, whose properties are also discussed. Then we transform multi-degree reduction of the error radius curve and the weight curve of the disk rational Bézier curve into solving a constrained quadratic progr...

An algorithmic approach to degree reduction of interval B-spline curve is presented in this paper. The curves that are useful in geometric modeling should have a relatively smooth shape and should be intuitively connected with the path of the sequence of control points. One family of curves satisfying this requirement is represented by the B-spline curves. The four fixed Kharitonov's polynomial...

Wang-Ball (WB) curve is one of the generalized cubic Ball basis which was first put forward in CONSURF system by Ball. Wang extended it to arbitrary odd and even degrees. An algorithmic approach to degree reduction of interval Wang-Ball curve is presented in this paper. The four fixed Kharitonov's polynomials (four fixed WB curves) associated with the original interval WB curve are obtained. Th...

In this paper, we propose the generalized B divided difference, with which the (k− 1)th derivative of B-spline curves of order k can be obtained directly without the need to compute the first (k − 2) derivatives as before. Based on the generalized B divided difference, the necessary and sufficient condition for degree-reducible B-spline curves is presented. Algorithms for degree reduction of B-...

Recently we developed a periodic surface model to assist the construction of nano structures parametrically for computer-aided nano-design. In this paper, we study the properties of periodic surfaces for degree elevation and reduction. Degree elevation approaches are developed to incrementally increase shape complexities, including native, variational, and boundary constrained elevations. A gen...

Interval Bézier curves are new representation forms of parametric curves that can embody a complete description of coefficient errors. Using this new representation, the problem of lack of robustness in all state-of-the-art CAD systems can be largely overcome. In this paper, we discuss the problem of bounding interval Bézier curves with lower degree interval Bézier curves. We propose two differ...

O. Ismail, Senior Member, IEEE Abstract— Fixed DP curve is a recent representation of the polynomial curves, proposed by Delgado and Pena in 2003. They introduced a new curve representation with linear computational complexity. An algorithmic approach to degree reduction of interval DP curve is presented in this paper. The four fixed Kharitonov's polynomials (four fixed DP curves) associated wi...

We study mappings obtained as s-periodic reductions of the lattice Korteweg-De Vries equation. For small s ∈ N we establish upper bounds on the growth of the degree of the numerator of their iterates. These upper bounds appear to be exact. Moreover, we conjecture that for s1, s2 co-prime the growth is ∼ (2s1s2)−1n2, except when s1 + s2 = 4 where the growth is linear ∼ n. Also, we conjecture the...

Ball basis was introduced for cubic polynomials by Ball, and was generalized for polynomials of higher degree by Said. An algorithmic approach to degree reduction of interval Said-Ball (SB) curve is presented in this paper. The four fixed Kharitonov's polynomials (four fixed SB curves) associated with the original interval SB curve are obtained. These four fixed SB curves are transformed into f...