共查询到20条相似文献,搜索用时 132 毫秒
1.
2.
测量样板圆弧中心距是工厂计量室经常遇到的问题之一。一般对小尺寸的圆弧样板可以在投影仪上以放大图相比较的方法进行测量,但有时遇到样板圆弧中心距离较大,通过一定投影放大后,在投影屏上不能全部投影出被测部位整个轮廓,这时除了可对被测圆弧作圆弧相切投影比较测量外,其中心距离就无法同时测量,本文就是在这种前提下介绍在万能显微镜上补充测量中心距离。现将在实际工作中所接触到的几块样板为例,对此方法作一简单介绍。例1:图1 a所示,已知:R、R_1(且R>R_1),要求测量 l 值。 相似文献
3.
印刷品质量检测颜色转换模型研究 总被引:1,自引:1,他引:0
目的研究印刷品质量检测中的颜色转换模型。方法基于色靶的测量数据,采用三维查找表法和多项式回归法,分别建立RGB与CIE L*a*b*颜色空间转换模型,并实验比较了2种算法转换模型的精度。结果三维查找表法转换模型的最大色差为3,四面体插值算法精度稍高于三线性、三棱柱和金字塔插值算法,平均色差为0.64;多项式回归算法的精度随着项数的增多而提高,20项的平均色差为2.58。结论三维查找表法转换模型精度高于多项式回归法,效果理想,能判断出CCD采集到的印刷图像是否存在色偏,且随着RGB颜色空间划分越细小,转换精度会越高。 相似文献
4.
5.
为了满足纳米级表面形貌样板的高精度非接触测量需求,研制了一种高分辨力光学显微测头。以激光全息单元为光源和信号拾取器件,利用差动光斑尺寸变化探测原理,建立了微位移测量系统,结合光学显微成像系统,形成了高分辨力光学显微测头。将该测头应用于纳米三维测量机,对台阶高度样板和一维线间隔样板进行了测量实验。结果表明:该光学显微测头结合纳米三维测量机可实现纳米级表面形貌样板的可溯源测量,具有扫描速度快、测量分辨力高、结构紧凑和非接触测量等优点,对解决纳米级表面形貌测量难题具有重要实用价值。 相似文献
6.
7.
本文在已有算法的基础上,提出了一个三维点集Delaunay三角剖分的自动生成及其修改算法。自动生成算法对点在空间的位置没有任何限制,修改算法充分利用已完成的计算量,当动态增加或减少一点时,仅在局部进行适当的调整即可保证整体三角剖分符合Delaunay性质。文中给出了算法正确性的证明。 相似文献
8.
9.
激光三角法距离传感:散斑的影响 总被引:7,自引:2,他引:5
描述了一个激光三角法距离传感,并用于鞋楦三维测量。讨论了系统的静态和动态测量误差,指出其深度分辨率主要由散斑决定,实验表明 ,增加透镜孔径或在成象透镜前加一随机振动位相掩膜均可极大改善深度分辨率。 相似文献
10.
11.
目的由误差扩散半色调算法得到的二值图像存在明显的规律性纹理,针对该问题提出随机中心聚集半色调算法。方法利用蓝噪声半色调阈值矩阵算法生成随机均匀分布的种子点,采用三角网生长算法构建Delaunay三角网格,在确定三角网像素成员后,根据像素点在三角形区域内的分布位置得到该位置像素的阈值,最后通过将连续调图像与阈值矩阵的阈值比较得到半色调图像。结果同误差扩散算法相比,提出的方法可以减少半色调图像的人工纹理,图像视觉效果较好。结论文中算法可以改善半色调图像质量,实验结果证明了该方法的有效性。 相似文献
12.
13.
S. H. Lo 《International journal for numerical methods in engineering》1989,28(11):2695-2707
This paper investigates the possibility of integrating the two currently most popular mesh generation techniques, namely the method of advancing front and the Delaunay triangulation algorithm. The merits of the resulting scheme are its simplicity, efficiency and versatility. With the introduction of ‘non-Delaunay’ line segments, the concept of using Delaunay triangulation as a means of mesh generation is clarified. An efficient algorithm is proposed for the construction of Delaunay triangulations over non-convex planar domains. Interior nodes are first generated within the planar domain. These interior nodes and the boundary nodes are then linked up together to produce a valid triangulation. In the mesh generation process, the Delaunay property of each triangle is ensured by selecting a node having the smallest associated circumcircle. In contrast to convex domains, intersection between the proposed triangle and the domain boundary has to be checked; this can be simply done by considering only the ‘non-Delaunay’ segments on the generation front. Through the study of numerous examples of various characteristics, it is found that high-quality triangular element meshes are obtained by the proposed algorithm, and the mesh generation time bears a linear relationship with the number of elements/nodes of the triangulation. 相似文献
14.
15.
对通信设备抗震试验方法进行了讨论,重点研究了NEBS GR-63-CORE抗震试验方法。针对抗震试验中地震模拟振动台频宽不够及存在非线性因素影响的问题,设计了地震模拟振动台三参量伺服控制算法,有效拓展了试验系统的频宽,提高试验系统的动态响应范围;并提出一种基于频域的驱动信号修正迭代算法,通过在线迭代修正驱动信号,补偿试验系统中非线性因素对系统的影响。NEBS GR-63-CORE抗震试验表明,基于三参量控制算法及驱动信号修正迭代算法的地震模拟振动台控制策略,能够实现高精度的地震波形复现试验。 相似文献
16.
A. Bykat 《International journal for numerical methods in engineering》1983,19(9):1375-1390
A recursive, shape controlling triangulation method is described. The method is designed to produce a labelling which implies reduced fill in the solution of (finite element) equations assembled from such a triangulation and allows simple implementation of a nested disection algorithm for irregular domains. This approach saves a substantial amount of time usually spent on discovering a suitable relabelling of the triangulation. In addition, the matrix of the resulting system is then endowed with a recursive doubly bordered block diagonal form. This allows us to develop a recursive parallel bisection method for the solution of the system of equations. 相似文献
17.
Abstract The Delaunay triangulation is broadly used on flat surfaces to generate well‐shaped elements. But the properties of Delaunay triangulation do not exist on curved surfaces whose Jacobians are different. In this paper we will present a modified algorithm to improve the shape of triangulation for the curved surface. The experiment results show that making use of “mapping factors” in the Delaunay triangulation and Laplacian method can produce better mesh (most aspect ratios≤3) on a curved surface. 相似文献
18.
二维任意域约束Delaunay三角化的实现 总被引:5,自引:0,他引:5
本文设计了一种逐点加入一局部换边法,提出并证明了二维约束边在约束Delaunay三角化中存在的条件,并据此用中点加点法实现了二维任意域的Delaunay三角剖分,生成的网格均符合Delaunay优化准则,网格的优化在网格生成过程中完成,算法复杂度与点数呈近似线性关系,给出了算法在平面域剖分和包含复杂断层的石油地质勘探散乱数据点集剖分的应用实例。 相似文献
19.
Biancardi L. Sansoni G. Docchio F. 《IEEE transactions on instrumentation and measurement》1995,44(1):36-41
An analysis of the sources of systematic errors in an optical whole-field profilometer based on the projection of fringes is presented here. In the system, the determination of the object profile is performed by triangulation. Both the period of the fringes and the geometrical system parameters on which triangulation operates (i.e. the distance between the object and the acquisition/projection units, and the distance between the acquisition unit and the projection unit) represent the input parameters of the profile evaluation algorithm. The influence on the height error introduced by an inaccuracy in the determination of the projected fringe period, as well as of the geometrical parameters of the system, is investigated here. The distortion in reconstructing the object shape due to the finite distance illumination scheme used in the system is also studied. The results obtained from the analysis are used to increase the accuracy at the optical profilometer by means of a suitably developed correction algorithm 相似文献