基于三元互补格雷码的条纹级次校正方法研究  

Fringe level correction method based on ternary complementary Gray code

作　　者：严飞[1,2] 祁健 刘银萍 于强[1] 刘佳 YAN Fei;QI Jian;LIU Yinping;YU Qiang;LIU Jia(College of Automation,Nanjing University of Information Science and Technology,Nanjing 210044,China;Jiangsu Provincial Collaborative Innovation Center for Atmospheric Environment and Equipment Technology,Nanjing 210044,China;College of Atmospheric Physics,Nanjing University of Information Science and Technology,Nanjing 210044,China)

机构地区：[1]南京信息工程大学自动化学院,江苏南京210044 [2]江苏省大气环境与装备技术协同创新中心,江苏南京210044 [3]南京信息工程大学大气物理学院,江苏南京210044

出　　处：《中国测试》2023年第8期41-46,共6页China Measurement & Test

基　　金：江苏省产业前瞻与关键核心技术重点项目(BE2020006-2);国家自然科学基金项目(61605083)。

摘　　要：利用二进制码辅助相移技术进行三维测量,可以有效地恢复出物体的连续相位。但是由于二进制图像的编码效率较低,n幅二进制编码图像只能对2n个周期进行编码,而使用三元格雷码编码可以将编码的周期级次数目提高到3n。然而格雷码灰度的增加,使得信噪比降低,条纹级次判决困难,导致相位展开出错,为此提出一种三元互补格雷码的相位展开方法。对于条纹级次边缘跳变的问题,增加一幅额外的三元格雷码图案,利用传统解得的码字与附加图案后解得码字的不同来互补边界跳变。且通过分区间映射相位级次方法对解得的码字所映射的相位级次再次位移,利用传统解得的相位级次和两个辅助相位级次同时对截断相位进行相位展开,使得可以避免边沿错误区域宽度小于2/3个条纹周期宽度时的误差。经实验本文方法较传统三元格雷码加相移方法均方根误差平均降低93.3%,结果表明所提出方法能够有效地避免边沿跳变误差,提高测量精度。Using the binary code-assisted phase-shifting technique for three-dimensional measurement can effectively recover the continuous phase of the object.However,due to the low coding efficiency of binary images,n binary coded images can only encode 2n cycles,while using ternary Gray code encoding can increase the number of coded cycle levels to 3n.However,the increase of gray level of Gray code reduces the signal-tonoise ratio,and the fringe order is difficult to judge,which leads to the error of phase unwrapping.Therefore,a phase unwrapping method of ternary complementary Gray code is proposed.For the problem of fringe-level edge transition,an additional ternary Gray code pattern is added,and the difference between the traditionally solved code-word and the decoded code-word after the additional pattern is used to complement the boundary transition.And the phase order mapped by the decoded code-word is shifted again by the method of mapping the phase order between partitions,and the phase order of the truncated phase is simultaneously phaseunwrapped by using the phase order obtained by the traditional solution and the two auxiliary phase orders,so that it is possible to avoid Error when the edge error area width is less than 2/3 of the stripe period width.Compared with the traditional ternary Gray code plus phase shift method,the root mean square error of the method in this paper is reduced by 93.3%.The results show that the proposed method can effectively avoid the edge transition error and improve the measurement accuracy.

关 键 词：三维测量 三元格雷码 相位展开 相位级次 

分 类 号：TN247[电子电信—物理电子学] TB9[一般工业技术—计量学]