基于数字相关的二值条纹投影轮廓术中离焦的定量评估方法  

Quantitative Evaluation of Binary Defocusing in Fringe Projection Profilometry Based on Digital Correlation

作　　者：江会交 尹卓异 张琴[1] 林清华[1] 林金兰[1] 康新[1,4] Jiang Huijiao;Yin Zhuoyi;Zhang Qin;Lin Qinghua;Lin Jinlan;Kang Xin(College of Electromechanical and Information Engineering,Putian University,Putian 351100,Fujian,China;College of Mechanical and Electrical Engineering,Fujian Agriculture and Forestry University,Fuzhou 350109,Fujian,China;School of Civil Engineering,Southeast University,Nanjing 211189,Jiangsu,China;School of Science,Nanjing University of Science and Technology,Nanjing 210094,Jiangsu,China)

机构地区：[1]莆田学院机电与信息工程学院,福建莆田351100 [2]福建农林大学机电工程学院,福建福州350109 [3]东南大学土木工程学院,江苏南京211189 [4]南京理工大学理学院,江苏南京210094

出　　处：《激光与光电子学进展》2023年第22期161-169,共9页Laser & Optoelectronics Progress

基　　金：江苏省研究生科研创新计划(KYCX22_0223);莆田学院研究生创新基金(2021101)。

摘　　要：为了消除投影仪的伽马效应,近年来二值条纹投影轮廓术得到快速发展。如何确定合适的离焦量是二值条纹离焦投影三维测量的关键问题。离焦不足时,条纹会包含高阶谐波;离焦过度的话,条纹对比度降低,相位分辨率降低,同时噪声的影响相对变大。离焦不足或离焦过度都会影响相位测量精度。为了解决这一问题,基于数字相关法提出一种最优离焦量的确定方法。该方法利用条纹与其二阶微分的相关性来确定最佳离焦量,以获得准正弦条纹。在欠离焦和过离焦情况下,相关系数均较小,只有当条纹为准正弦条纹时,相关系数取得极大值。对该方法进行了数值模拟和实验验证。实验结果表明,所提方法具有速度快、准确性高的优点,可在二值条纹投影过程中实时跟踪相关系数并确定最佳离焦量。Binary fringe projection profilometry has experienced significant growth in recent years to eliminate the gamma effect of projectors.Determining the appropriate defocus amount is crucial for three-dimensional measurement in binary fringe defocus projection.Insufficient defocusing can result in fringes containing higher-order harmonics,while excessive defocusing can reduce fringe contrast,decrease phase resolution,and relatively increase noise impact.Both insufficient and excessive defocusing can affect the phase measurements accuracy.To address this problem,a method for determining the optimal defocus amount based on digital correlation is proposed.This method utilizes the correlation between fringes and their second-order derivatives to determine the optimal defocus amount and achieve quasi-sinusoidal fringes.In both under-defocus and over-defocus situations,the correlation coefficient is small,and it reaches its maximum value only when the fringes are quasi sinusoidal.The method was numerically simulated and experimentally validated.The experimental results show that the proposed method offers fast speed and high accuracy,enabling real-time tracking of the correlation coefficient during the binary fringe projection process and determining the optimal defocus amount.

关 键 词：成像系统 二值离焦 数字相关 定量评估 二阶微分 条纹投影轮廓术 

分 类 号：TP319[自动化与计算机技术—计算机软件与理论]