Improved Butterfly Subdivision Scheme for Meshes with Arbitrary Topology

Based on the butterfly subdivision scheme and the modified butterfly subdivision scheme, an improved butterfly subdivision scheme is proposed. The scheme uses a small stencil of six points to calculate new inserting vertex, 2n new vertices are inserted in the 2n triangle faces in each recursion, and the n old vertices are kept, special treatment is given to the boundary, achieving higher smoothness while using small stencils is realized. With the proposed scheme, the number of triangle faces increases only by a factor of 3 in each refinement step. Compared with the butterfly subdivision scheme and the modified butterfly subdivision scheme, the size of triangle faces changes more gradually, which allows one to have greater control over the resolution of a refined mesh.

Two-order Hermite vector-interpolating subdivision schemes

A family of two-order Hermite vector-interpolating subdivision schemes is proposed and its convergence and con- tinuity are analyzed. The iterative level can be estimated for given error. The sufficient conditions of C2 continuity are proved. Geometric features of subdivision curves, such as line segments, cusps and inflection points, are obtained by appending some conditions to initial vectorial Hermite sequence. An algorithm is presented for generating geometric features. For an initial se- quence of two-order Hermite elements from unit circle, the numerical error of the 4th subdivided level is O(10?4).

CONVERGENCE OF SUBDIVISION SCHEMES IN L_p SPACES

In this paper it is proved that L p solutions of a refinement equation exist if and only if the corresponding subdivision scheme with suitable initial function converges in L p without any assumption on the stability of the solutions of the refinement equation.A characterization for convergence of subdivision scheme is also given in terms of the refinement mask.Thus a complete answer to the relation between the existence of L p solutions of the refinement equation and the convergence of the corresponding subdivision schemes is given.

CONVERGENCE RATE OF VECTOR SUBDIVISION SCHEME

In this paper, some characterizations on the convergence rate of both the homogeneous and nonhomogeneous subdivision schemes in Sobolev space are studied and given.

COMPUTATION OF CONTINUOUS WAVELET TRANSFORM AT DYADIC SCALES BY SUBDIVISION SCHEME

A new algorithm to compute continuous wavelet transforms at dyadic scales is proposed here. Our approach has a similar implementation with the standard algorithme a trous and can coincide with it in the one dimensional lower order spline case.Our algorithm can have arbitrary order of approximation and is applicable to the multidimensional case.We present this algorithm in a general case with emphasis on splines anti quast in terpolations.Numerical examples are included to justify our theorerical discussion.

A UNIFIED THREE POINT APPROXIMATING SUBDIVISION SCHEME

In this paper, we propose a three point approximating subdivision scheme, with three shape parameters, that unifies three different existing three point approximating schemes. Some sufficient conditions for subdivision curve C0 to C3 continuity and convergence of the scheme for generating tensor product surfaces for certain ranges of parameters by using Laurent polynomial method are discussed. The systems of curve and surface design based on our scheme have been developed successfully in garment CAD especially for clothes modelling.

Vector refinement equation and subdivision schemes in Lp spaces

In this paper we will first prove that the nontrivial L p solutions of the vector refinement equation exist if and only if the corresponding subdivision scheme with a suitable initial function converges in L p without assumption of the stability of the solutions. Then we obtain a characterization of the convergence of the subdivision scheme in terms of the mask. This gives a complete answer to the existence of L p solutions of the refinement equation and the convergence of the corresponding subdivision schemes.

CHARACTERIZATION OF COVERGENT SUBDIVISION SCHEMES

Subdivision schemes provide important techniques for the fast generation of curves and surfaces. A recusive refinement of a given control polygon will lead in the limit to a desired visually smooth object. These methods play also an important role in wavelet analysis. In this paper, we use a rather simple way to characterize the convergence of subdivision schemes for multivariate cases. The results will be used to investigate the regularity of the solutions for dilation equations.

A Note on the Continuity of the Generalized Curve Subdivision Scheme with Tension Parameter

A generalized non-stationary curve subdivision （GNS for short） scheme of arbitrary order k≥3 with a parameter has been proposed by Fang et al. in the paper （Fang Mei-e et al., CAGD, 2010（27）： 720-733）. It has been proved that the proposed scheme of order k generates C^k-2 continuous curves for k≥4. But the proof of the smoothness in this paper is uncompleted. Moreover, the Cl-continuity of the third order scheme has not been discussed. For this reason, in this paper, we provide a full corrected proof of the smoothness of the GNS scheme of order k for k≥3.

Vector subdivision schemes in (L_p(R^5))~r(1≤p≤∞) spaces

The purpose of this paper is to investigate the refinement equations of the formwhere the vector of functions = (1, … ,r)T is in (LP(R8))T,1 ≤ p ≤∞, α(α),α ∈ Z5, is a finitely supported sequence of r × r matrices called the refinement mask, and M is an s x a integer matrix such that limn→ ∞ M-n = 0. In order to solve the refinement equation mentioned above, we start with a vector of compactly supported functions (0 ∈ (LP(R8))r and use the iteration schemes fn := Qan0,n = 1,2,…, where Qa is the linear operator defined on (Lp(R8))r given byThis iteration scheme is called a subdivision scheme or cascade algorithm. In this paper, we characterize the Lp-convergence of subdivision schemes in terms of the p-norm joint spectral radius of a finite collection of some linear operators determined by the sequence a and the set B restricted to a certain invariant subspace, where the set B is a complete set of representatives of the distinct cosets of the quotient group Z8/MZ8 containing 0.

Statistical and Geometrical Way of Model Selection for a Family of Subdivision Schemes

The objective of this article is to introduce a generalized algorithm to produce the m-point n-ary approximating subdivision schemes(for any integer m, n ≥ 2). The proposed algorithm has been derived from uniform B-spline blending functions. In particular, we study statistical and geometrical/traditional methods for the model selection and assessment for selecting a subdivision curve from the proposed family of schemes to model noisy and noisy free data. Moreover, we also discuss the deviation of subdivision curves generated by proposed family of schemes from convex polygonal curve. Furthermore, visual performances of the schemes have been presented to compare numerically the Gibbs oscillations with the existing family of schemes.

Generalized and Unified Families of Interpolating Subdivision Schemes

We present generalized and unified families of (2n)-point and (2n − 1)-point p-ary interpolating subdivision schemes originated from Lagrange polynomialfor any integers n ≥ 2 and p ≥ 3. Almost all existing even-point and odd-pointinterpolating schemes of lower and higher arity belong to this family of schemes. Wealso present tensor product version of generalized and unified families of schemes.Moreover error bounds between limit curves and control polygons of schemes arealso calculated. It has been observed that error bounds decrease when complexityof the scheme decrease and vice versa. Furthermore, error bounds decrease withthe increase of arity of the schemes. We also observe that in general the continuityof interpolating scheme do not increase by increasing complexity and arity of thescheme.

Some Sufficient Conditions for Convergent Multivariate Subdivision Schemes with Nonnegative Finite Masks

It is well known that the convergence of multivariate subdivision schemes with finite masks can be characterized via joint spectral radius. For nonnegative masks, we will present in this paper some computable simply sufficient conditions for the convergence, which will cover a substantially large class of schemes.

Improved Ternary Subdivision Interpolation Scheme

An improved ternary subdivision interpolation scheme was developed for computer graphics ap- plications that can manipulate open control polygons unlike the previous ternary scheme, with the resulting curve proved to be still C2-continuous. Parameterizations of the limit curve near the two endpoints are given with expressions for the boundary derivatives. The split joint problem is handled with the interpolating ter- nary subdivision scheme. The improved scheme can be used for modeling interpolation curves in computer aided geometric design systems, and provides a method for joining two limit curves of interpolating ternary subdivisions.

基于关键阈值设定的危险性较大的分部分项工程方案预警系统设计与实现

为避免大型建筑公司大量危险性较大的分部分项工程(即危大工程)方案人力管控的疏漏和易出现危大工程方案滞后等不利情况,采用信息化手段开发了一款软件。通过对各类典型危大工程方案滞后问题的研究,对关键阈值进行设定,开发出了危大工程方案预警系统,利用该系统,有效解决了危大工程方案滞后问题,可为类似项目提供经验借鉴。