The existing results of curve degree elevation mainly focus on the degree of algebraic polynomials. The paper considers the elevation of degree of the trigonometric polynomial, from a Bezier curve on the algebraic pol...The existing results of curve degree elevation mainly focus on the degree of algebraic polynomials. The paper considers the elevation of degree of the trigonometric polynomial, from a Bezier curve on the algebraic polynomial space, to a C-Bezier curve on the algebraic and trigonometric polynomial space. The matrix of degree elevation is obtained by an operator presentation and a derivation pyramid. It possesses not a recursive presentation but a direct expression. The degree elevation process can also be represented as a corner cutting form.展开更多
De Casteljau algorithm and degree elevation of Bézier and NURBS curves/surfaces are two important techniques in computer aided geometric design. This paper presents the de Casteljau algorithm and degree elevation...De Casteljau algorithm and degree elevation of Bézier and NURBS curves/surfaces are two important techniques in computer aided geometric design. This paper presents the de Casteljau algorithm and degree elevation of toric surface patches, which include tensor product and triangular rational Bézier surfaces as special cases. Some representative examples of toric surface patches with common shapes are illustrated to verify these two algorithms. Moreover, the authors also apply the degree elevation of toric surface patches to isogeometric analysis. And two more examples show the effectiveness of proposed method.展开更多
Unified and extended splines(UE-splines), which unify and extend polynomial, trigonometric, and hyperbolic B-splines, inherit most properties of B-splines and have some advantages over B-splines. The interest of this ...Unified and extended splines(UE-splines), which unify and extend polynomial, trigonometric, and hyperbolic B-splines, inherit most properties of B-splines and have some advantages over B-splines. The interest of this paper is the degree elevation algorithm of UE-spline curves and its geometric meaning. Our main idea is to elevate the degree of UE-spline curves one knot interval by one knot interval. First, we construct a new class of basis functions, called bi-order UE-spline basis functions which are defined by the integral definition of splines.Then some important properties of bi-order UE-splines are given, especially for the transformation formulae of the basis functions before and after inserting a knot into the knot vector. Finally, we prove that the degree elevation of UE-spline curves can be interpreted as a process of corner cutting on the control polygons, just as in the manner of B-splines. This degree elevation algorithm possesses strong geometric intuition.展开更多
In this paper, we improve the generalized Bernstein basis functions introduced by Han, et al. The new basis functions not only inherit the most properties of the classical Bernstein basis functions, but also reserve t...In this paper, we improve the generalized Bernstein basis functions introduced by Han, et al. The new basis functions not only inherit the most properties of the classical Bernstein basis functions, but also reserve the shape parameters that are similar to the shape parameters of the generalized Bernstein basis functions. The degree elevation algorithm and the conversion formulae between the new basis functions and the classical Bernstein basis functions are obtained. Also the new Q-Bezier curve and surface constructed by the new basis functions are given and their properties are discussed.展开更多
This paper presents a new basis, the WSB basis, which unifies the Bemstein basis, Wang-Ball basis and Said-Ball basis, and therefore the Bézier curve, Wang-Ball curve and Said-Ball curve are the special cases of ...This paper presents a new basis, the WSB basis, which unifies the Bemstein basis, Wang-Ball basis and Said-Ball basis, and therefore the Bézier curve, Wang-Ball curve and Said-Ball curve are the special cases of the WSB curve based on the WSB basis In addition, the relative degree elevation formula, recursive algorithm and conversion formula between the WSB basis and the Bern- stein basis are given.展开更多
A degree elevation formula for multivariate simplex splines was given by Micchelli and extended to hold for multivariate Dirichlet splines in [8]. We report similar formulae for multivariate cone splines and box splin...A degree elevation formula for multivariate simplex splines was given by Micchelli and extended to hold for multivariate Dirichlet splines in [8]. We report similar formulae for multivariate cone splines and box splines. To this end, we utilize a relation due to Dahmen and Micchelli that connects box splines and cone splines and a degree reduction formula given by Cohen, Lyche, and Riesenfeld in [2].展开更多
This paper presents two new families of the generalized Ball curves which include the Be ′zier curve, the generalized Ball curves defined by Wang and Said independently and some intermediate curves. The relati...This paper presents two new families of the generalized Ball curves which include the Be ′zier curve, the generalized Ball curves defined by Wang and Said independently and some intermediate curves. The relative degree elevation and reduction schemes, recursive algorithms and the Bernstein\|Be ′zier representation are also given.展开更多
In this paper, we investigate the inherent relationship between two types of rational Bezier surfaces. We present a conversion formula for rational Bezier surfaces from triangular patches to rectangular patches with s...In this paper, we investigate the inherent relationship between two types of rational Bezier surfaces. We present a conversion formula for rational Bezier surfaces from triangular patches to rectangular patches with straight forward geometric interpretations, an inverse process of such conversion is also considered.展开更多
A new type of bivariate generalized Ball basis function on a triangle is presented for free-form surface design. Some properties of the basis function are given, then degree elevation, recursive evaluation and some ot...A new type of bivariate generalized Ball basis function on a triangle is presented for free-form surface design. Some properties of the basis function are given, then degree elevation, recursive evaluation and some other properties of the generalized Ball surfaces are also derived. It is shown that the proposed recursive evaluation algorithm is more efficient than those of the old surfaces.展开更多
基金Supported by the National Natural Science Foundation of China(61402201,11326243,61272300,11371174)the Jiangsu Natural Science Foundation of China(BK20130117)
文摘The existing results of curve degree elevation mainly focus on the degree of algebraic polynomials. The paper considers the elevation of degree of the trigonometric polynomial, from a Bezier curve on the algebraic polynomial space, to a C-Bezier curve on the algebraic and trigonometric polynomial space. The matrix of degree elevation is obtained by an operator presentation and a derivation pyramid. It possesses not a recursive presentation but a direct expression. The degree elevation process can also be represented as a corner cutting form.
基金supported by the National Natural Science Foundation of China under Grant Nos.11671068 and 11801053。
文摘De Casteljau algorithm and degree elevation of Bézier and NURBS curves/surfaces are two important techniques in computer aided geometric design. This paper presents the de Casteljau algorithm and degree elevation of toric surface patches, which include tensor product and triangular rational Bézier surfaces as special cases. Some representative examples of toric surface patches with common shapes are illustrated to verify these two algorithms. Moreover, the authors also apply the degree elevation of toric surface patches to isogeometric analysis. And two more examples show the effectiveness of proposed method.
基金Project supported by the National Natural Science Foundation of China(Nos.60933008 and 61272300)
文摘Unified and extended splines(UE-splines), which unify and extend polynomial, trigonometric, and hyperbolic B-splines, inherit most properties of B-splines and have some advantages over B-splines. The interest of this paper is the degree elevation algorithm of UE-spline curves and its geometric meaning. Our main idea is to elevate the degree of UE-spline curves one knot interval by one knot interval. First, we construct a new class of basis functions, called bi-order UE-spline basis functions which are defined by the integral definition of splines.Then some important properties of bi-order UE-splines are given, especially for the transformation formulae of the basis functions before and after inserting a knot into the knot vector. Finally, we prove that the degree elevation of UE-spline curves can be interpreted as a process of corner cutting on the control polygons, just as in the manner of B-splines. This degree elevation algorithm possesses strong geometric intuition.
基金supported by the National Natural Science Foundations of China (61070065, 60933007)
文摘In this paper, we improve the generalized Bernstein basis functions introduced by Han, et al. The new basis functions not only inherit the most properties of the classical Bernstein basis functions, but also reserve the shape parameters that are similar to the shape parameters of the generalized Bernstein basis functions. The degree elevation algorithm and the conversion formulae between the new basis functions and the classical Bernstein basis functions are obtained. Also the new Q-Bezier curve and surface constructed by the new basis functions are given and their properties are discussed.
基金Supported by the Key Project of Chinese Ministry of Education(No.309017)the National Natural Science Foundation of China(No.60473114)the Anhui Provincial Natural Science Foundation(No.07041627)
文摘This paper presents a new basis, the WSB basis, which unifies the Bemstein basis, Wang-Ball basis and Said-Ball basis, and therefore the Bézier curve, Wang-Ball curve and Said-Ball curve are the special cases of the WSB curve based on the WSB basis In addition, the relative degree elevation formula, recursive algorithm and conversion formula between the WSB basis and the Bern- stein basis are given.
文摘A degree elevation formula for multivariate simplex splines was given by Micchelli and extended to hold for multivariate Dirichlet splines in [8]. We report similar formulae for multivariate cone splines and box splines. To this end, we utilize a relation due to Dahmen and Micchelli that connects box splines and cone splines and a degree reduction formula given by Cohen, Lyche, and Riesenfeld in [2].
文摘This paper presents two new families of the generalized Ball curves which include the Be ′zier curve, the generalized Ball curves defined by Wang and Said independently and some intermediate curves. The relative degree elevation and reduction schemes, recursive algorithms and the Bernstein\|Be ′zier representation are also given.
文摘In this paper, we investigate the inherent relationship between two types of rational Bezier surfaces. We present a conversion formula for rational Bezier surfaces from triangular patches to rectangular patches with straight forward geometric interpretations, an inverse process of such conversion is also considered.
基金This work was supported by the National Natural Science Foundation of China and China Postdoctoral Science Foundation. The secon
文摘A new type of bivariate generalized Ball basis function on a triangle is presented for free-form surface design. Some properties of the basis function are given, then degree elevation, recursive evaluation and some other properties of the generalized Ball surfaces are also derived. It is shown that the proposed recursive evaluation algorithm is more efficient than those of the old surfaces.
