基于伸缩因子的代数曲线曲面变形方法

提出了一种基于伸缩因子的代数曲线曲面变形方法。首先构造了一种用于代数曲线曲面变形的伸缩因子,然后将所构造的伸缩因子分别作用于待变形的代数曲线与曲面,通过改变伸缩因子各参数的取值实现对代数曲线曲面的变形。实例表明,该方法操作方便,易于控制,可获得丰富的变形效果,是一种简单有效的代数曲线曲面变形方法。     

SMT封装电路板三维在线检测技术

为了检测回流焊接之后SMT( Surface Mount Technology)封装电路板是否存在缺陷,设计并搭建了基于线结构光传感器的SMT封装电路板三维在线检测系统,通过线结构光扫描测量,获取SMT封装电路板表面三维数据。采用双传感器测量技术,有效减少数据丢失;研究了双传感器统一标定技术,可同时实现两个传感器的参数标定和坐标系统一。提出了自适应光条中心提取算法,对反射或散射影响而形成的光条图像噪声具有很好的抑制效果,能够提取准确的光条中心。实验表明系统测量精度可达到0.02 mm。系统测量得到的三维数据,可以为在线检测SMT封装电路板缺陷提供可靠的三维信息。     

Mbius-invariant curve and surface energies and their applications

Curvature-based surface energies are frequently used in mathematics, physics, thin plate and shell engineering, and membrane chemistry and biology studies. Invariance under rotations and shifts makes curvature-based energies very attractive for modeling various phenomena. In computer-aided geometric design, the Willmore surfaces and the so-called minimum variation surfaces （MVS） are widely used for shape modeling purposes. The Willmore surfaces are invariant w.r.t conformal transformations （Mbius or conformal invariance）, and studied thoroughly in differential geometry and related disciplines. In contrast, the minimum variation surfaces are not conformal invariant. In this paper, we suggest a simple modification of the minimum variation energy and demonstrate that the resulting modified MVS enjoy Mbius invariance （so we call them conformal-invariant MVS or, shortly, CI-MVS）. We also study connections of CI-MVS with the cyclides of Dupin. In addition, we consider several other conformal-invariant curve and surface energies involving curvatures and curvature derivatives. In particular, we show how filtering with a conformal-invariant curve energy can be used for detecting salient subsets of the principal curvature extremum curves used by Hosaka and co-workers for shape quality inspection purposes.     

Measurement by vertical scanning profilometry of resorption volume and lacunae depth caused by osteoclasts on dentine slices

The resorption pit assay is classically used to evaluate osteoclast activity on bone or dentine slices that can be eroded by these cells. Two different types of cells were generated from peripheral blood mononuclear cells cultured in the presence of M-CSF + sRANKL or with M-CSF + LPS. At the end of the culture period (21 days), cells were discarded and the dentine slices stained with toluidine blue and examined with an NT9100 Wyco vertical scanning profilometer. The images of the dentine surface were corrected for tilt and the eroded volume was calculated on the whole images. The depth of the eroded pits was determined. The data files were used to reconstruct the surface of the slices by standardizing the ground level to compare both conditions. Osteoclasts generated with M-CSF + sRANKL were capable of resorbing a more important volume than those generated with M-CSF + LPS. In addition, the formers were able to resorb the dentine matrix more deeply. Data provided by the microscope were used to reconstruct three-dimensional images of the dentine slices with pseudo colours varying with the depth of erosion. Vertical scanning profilometry, a technique used to measure the roughness of polished or etched surfaces in metallurgic industry, can be used to accurately measure the eroded volume and the mean erosion depth done by osteoclasts in the resorption pit assay.     

MTi: A method for user identification for multitouch displays

This paper describes MTi, a biometric method for user identification on multitouch displays. The method is based on features obtained only from the coordinates of the 5 touchpoints of one of the user's hands. This makes MTi applicable to all multitouch displays large enough to accommodate a human hand and detect 5 or more touchpoints without requiring additional hardware and regardless of the display's underlying sensing technology. MTi only requests that the user places his hand on the display with the fingers comfortably stretched apart. A dataset of 34 users was created on which our method reported 94.69% identification accuracy. The method's scalability was tested on a subset of the Bosphorus hand database (100 users, 94.33% identification accuracy) and a usability study was performed.     

Modeling on triangulations with geodesic curves

This paper discusses the problem of modeling on triangulated surfaces with geodesic curves. In the first part of the paper we define a new class of curves, called geodesic Bézier curves, that are suitable for modeling on manifold triangulations. As a natural generalization of Bézier curves, the new curves are as smooth as possible. In the second part we discuss the construction of C ⁰ and C ¹ piecewise Bézier splines. We also describe how to perform editing operations, such as trimming, using these curves. Special care is taken to achieve interactive rates for modeling tasks. The third part is devoted to the definition and study of convex sets on triangulated surfaces. We derive the convex hull property of geodesic Bézier curves.

弧齿锥齿轮数控加工和齿面接触点求解算法研究

在保证弧齿锥齿轮加工过程中刀盘相对于工件的运动关系不变的基础上,通过矩阵变换实现铣齿加工的数控展成.由于在数控加工每个插补周期中难以实现这种涉及大量运算的运动转换,因此将数控坐标轴的展成运动表示为以工件齿轮转角为参数的五次参数样条函数,保证了插补的实时性和精确性.文中将传统用于确定接触点位置时求解非线性方程组的问题,转化为带有3个设计变量的约束优化问题,简化了法线重合的条件,建立配对齿轮位置矢量相等的目标函数.最后给出实例对算法进行了说明和验证.     

Space Deformations, Surface Deformations and the Opportunities In-Between

In recent years we have witnessed a large interest in surface deformation techniques. This has been a reaction that can be attributed to the ability to develop techniques which are detail-preserving. Space deformation techniques, on the other hand, received less attention, but nevertheless they have many advantages over surface-based techniques. This paper explores the potential of these two approaches to deformation and discusses the opportunities that the fusion of the two may lead to. Electronic Supplementary Material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

云南民族包设计中的点、线、面

点、线、面元素是艺术设计最基本的元素,在云南民族包设计中普遍运用。本论文主要从点、线、面的性质和作用来阐述了点线面元素是如何在云南民族包设计中得到运用的,从而使民族包的语言得到了充分的发挥。     

细分曲面求交交线计算方法的研究

主要针对三角网格的细分曲面求交提出了一种有效的交线计算的方法,该方法适用于任意三角网格的细分曲面中.在利用AABB和二部图进行初始控制网格相交性检测后,利用该方法快速有效地求出细分曲面的交线.