投影栅线法形貌测量中相位恢复和相位展开算法研究
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摘要
投影栅相位法是三维形貌测量技术的一种非常重要的技术,它将光栅图样投影到被测物体表面,受物体高度信息调制光栅图样变形,变形栅像可以看作相位被高度信息调制的空间载频信号,这样各点的高度信息可以转化为计算各点的相位信息。自八十年代以来人们对投影栅相位法的研究越来越多,投影栅线法由于采用白光做光源,克服了用激光光源检测时对环境要求高的缺陷,有利于精确的三维形貌测量系统产品化。
目前投影栅线法三维测量技术已经取得了很大的进展,但针于具有复杂表面物体测量时的阴影问题、测量精度、自动化程度等方面都存在一定的局限。现有的方法可能针对某一方面有所突破,但仅仅适用于测量特定的物体。随科技和工业技术的进一步发展,不同领域对三维形貌测量的精度、测量范围及实用性等方面的要求愈来愈高。因此,国内外许多研究人员都在不断进行研究,争取有更理想的新方法或对已有方法进行改进,以满足需求。
本文主要针对投影栅线法三维测量技术中的两个关键技术相位提取和相位展开进行了研究。在现有相位提取算法的基础上,改进了最小方差迭代算法,并对该方法迭代时的相移量偏差进行了分析,通过迭代相移量的偏差可以减小一个数量级,从而提高了相位提取的精度;相位展开方面;借鉴图像分割思想,提出了新的多种点区域生长去包裹算法。实验表明该方法可以有效解决复杂表面物体去包裹时存在的阴影问题,成功实现了绕空洞去包裹。
在进行理论、方法研究的同时,合理配置硬件设备,搭建了一套简易、灵活、操作方便的投影栅测量系统。并基于C++ Builder5.0,在老师的指导下和课题组另一位同学共同开发了测量系统软件,可以实现物体高精度的三维形貌测量。该平台能自动生产虚拟正弦光栅,设置光栅参数,图像灰度变换、滤波等几何变换,该平台能实现N步相移法,非定步长法、迭代方法提取截断相位,区域生长法等绕空洞去包裹处理,以及系统标定、三维重构等功能。图像均随时显示,与之对应的点云数据可以方便的导出,这不仅大大方便了对处理结果进行分析和参数的选择,而且为实际测量,数据处理提供了不可或缺的依据。
The phase method based on grating projection is one very important method of 3D measuring profilometry technology. The fringe was projected to the surface of the measured object, and the deformation fringe can be viewed as modulated carrier signal by phase. Since 1980s the phase method based on grating projection has been paid more attention to, it relaxed the environmental requirements when using white light and it is conducive to product forming of the measurement system.
At present the phase method has achieved great progress. But there are still a certain limitations on some aspects, such as the shadow problem when measuring objects with complex surface, and precision and automation is also problems needed further resolved. Present methods may be adapt to measuring some specific objects. So with the development of science and industrial technology, some new practicable method or improvement should be studied, which meet the demand of high precision and automation.
In this paper the phase extraction and phase unwrapping were mainly focused on, which is the two key techniques of 3D measuring profilometry. Based on the traditional phase extraction algorithms, the least-square iterative algorithm was improved, which depress the noise affectation efficiently and advanced the measurement precision. About the phase unwrapping, a new algorithm—Multi-seeds Region Growing phase unwrapping method—was proposed. The algorithm is based on the analysis of modulation and reference the thinking of image segmentation. Experimental results show that it can resolve the shadow problem of complex objects successfully.
An image processing software was programmed in C++Builder5.0 by the guide of my supervisor, and with another classmate. The software can produce virtual fringe and setting the parameters of the fringe. It also has the functions as calculation and image processing of phase extraction、 phase unwrapping and objects reconstruction, reading and saving image file, data in every step of processing and so on .The software is easy in use and convenient in adjust parameters; It has provided indispensable theoretical foundation for practical measuring and data processing.
目前投影栅线法三维测量技术已经取得了很大的进展,但针于具有复杂表面物体测量时的阴影问题、测量精度、自动化程度等方面都存在一定的局限。现有的方法可能针对某一方面有所突破,但仅仅适用于测量特定的物体。随科技和工业技术的进一步发展,不同领域对三维形貌测量的精度、测量范围及实用性等方面的要求愈来愈高。因此,国内外许多研究人员都在不断进行研究,争取有更理想的新方法或对已有方法进行改进,以满足需求。
本文主要针对投影栅线法三维测量技术中的两个关键技术相位提取和相位展开进行了研究。在现有相位提取算法的基础上,改进了最小方差迭代算法,并对该方法迭代时的相移量偏差进行了分析,通过迭代相移量的偏差可以减小一个数量级,从而提高了相位提取的精度;相位展开方面;借鉴图像分割思想,提出了新的多种点区域生长去包裹算法。实验表明该方法可以有效解决复杂表面物体去包裹时存在的阴影问题,成功实现了绕空洞去包裹。
在进行理论、方法研究的同时,合理配置硬件设备,搭建了一套简易、灵活、操作方便的投影栅测量系统。并基于C++ Builder5.0,在老师的指导下和课题组另一位同学共同开发了测量系统软件,可以实现物体高精度的三维形貌测量。该平台能自动生产虚拟正弦光栅,设置光栅参数,图像灰度变换、滤波等几何变换,该平台能实现N步相移法,非定步长法、迭代方法提取截断相位,区域生长法等绕空洞去包裹处理,以及系统标定、三维重构等功能。图像均随时显示,与之对应的点云数据可以方便的导出,这不仅大大方便了对处理结果进行分析和参数的选择,而且为实际测量,数据处理提供了不可或缺的依据。
The phase method based on grating projection is one very important method of 3D measuring profilometry technology. The fringe was projected to the surface of the measured object, and the deformation fringe can be viewed as modulated carrier signal by phase. Since 1980s the phase method based on grating projection has been paid more attention to, it relaxed the environmental requirements when using white light and it is conducive to product forming of the measurement system.
At present the phase method has achieved great progress. But there are still a certain limitations on some aspects, such as the shadow problem when measuring objects with complex surface, and precision and automation is also problems needed further resolved. Present methods may be adapt to measuring some specific objects. So with the development of science and industrial technology, some new practicable method or improvement should be studied, which meet the demand of high precision and automation.
In this paper the phase extraction and phase unwrapping were mainly focused on, which is the two key techniques of 3D measuring profilometry. Based on the traditional phase extraction algorithms, the least-square iterative algorithm was improved, which depress the noise affectation efficiently and advanced the measurement precision. About the phase unwrapping, a new algorithm—Multi-seeds Region Growing phase unwrapping method—was proposed. The algorithm is based on the analysis of modulation and reference the thinking of image segmentation. Experimental results show that it can resolve the shadow problem of complex objects successfully.
An image processing software was programmed in C++Builder5.0 by the guide of my supervisor, and with another classmate. The software can produce virtual fringe and setting the parameters of the fringe. It also has the functions as calculation and image processing of phase extraction、 phase unwrapping and objects reconstruction, reading and saving image file, data in every step of processing and so on .The software is easy in use and convenient in adjust parameters; It has provided indispensable theoretical foundation for practical measuring and data processing.
引文
[1]C.Quan,C.J.Tay,X.Y.He,X.Kang,H.M.Shang Microscopic surface contouring by fringe projection method,Optics& Laser Technology 2002,34:547-552.
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[10]周灿林,亢一澜.三维形貌检测中自动参考栅技术的改进。光学技术,2004,30:587-589,593.
[11]司书春,王蕴珊,于复生,周灿林。基于投影栅相位法的透明体表面微观形貌测量.光电子·激光2001.3:275-284.
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[29].H.Miao,C.Quan,C.J.Tay and Y.Fu.Analysis of phase distortion in phase-shifted fringe projection.Opt Lasers Eng 2007;45:318-325.
[30].Adam Styk,Krzysztof Patorski.Identification of nonlinear recording error in phase shifting interferometry.Opt.Lasers Eng,2007,45:265-273.
[31].Harmeet Singh and James S.Sirkis.Direct extraction of phase gradients form Fourier-transform and phase-step fringe patterns.Appl.Opt,1994,33(22),5016-5020.
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[36]苏显渝,李继陶.信息光学[M],p321-335.
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[40]GD Lassahn,JK Lassahn,PL Talor,VA Deason.Multiphase fringe analysis with unknown phase shifts.Opt.Eng.1994,33:2039-2044.
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[2]T Yi,CJ Kim.Measurement of mechanical properties for MEMS materials.Measurement Science and Technology,1999;10:706-16.
[3]Brown GC,Pryputniewicz RJ.New test methodology for static and dynamic shape measurement of micro electro mechanical systems.Opt Eng 2000;39(1):127-136.
[4]Hiroo,Ken Yamatan,Masayuki Yamamoto,Yukitishi Otani.Three-dimensional profilometry using liquid crystal grating.Proc.SPIE,2003,5058:51-60.
[5]X.Y.He,Kang,C.Quan,etc.Optical method for the measurement of MEMS materials and structures.Proc,SPIE,2001,10:63-68.
[6]HE H T,CHEN M Y,GUO H W.Shape measurement of complex objects using connection techniques based on overlap-pingareas[J].SPIE,2003,5180:402-412.
[7]郝煜栋,赵洋,李达成,光学投影式三维轮廓测量技术综述,光学技术.1998,(5):57-60.
[8]梁永强,韩耕,伍小平.全景三维轮廓检测技术的应用,应用激光,2001,21:313-316.
[9]徐建强,王蕴珊。三维形貌检测的自动参考栅像法研究.光子学报,1998,26(6):553-557.
[10]周灿林,亢一澜.三维形貌检测中自动参考栅技术的改进。光学技术,2004,30:587-589,593.
[11]司书春,王蕴珊,于复生,周灿林。基于投影栅相位法的透明体表面微观形貌测量.光电子·激光2001.3:275-284.
[12]王昭,赵宏,谭玉山.相移阴影莫尔轮廓术的相位去包裹处理新技术.半导体光电,1998,19(5):347-350.
[13]康新,何小元.两步相移实现投影栅相位测量轮廓术.光学学报,2003(1):75-79.
[14]高成勇,王蕴珊,司书春,徐建强.一种基于非定步长相移相位恢复算法的研究.光电子·激光,2002,13(9):956-958.
[15]康新,何小元.基于正弦条纹投影的三维传感及其去包裹处理。光学学报,2001,21(12):1444-1447.
[16]Levine M D,Handly D,Yaki G.Computer Determination of Depth Maps,C G IP.,1973,2:134-150
[17]Yakimovsky Y,Cunningham R.i System for Extracting Three - dimensional Measurements from a Stereo pair of TV Cameras.C.G.I P.,1978,7:195-210.
[18]Moravec H P.Towards Automatic Visual Obstacle A Voidance,Proc 5th,Cambridge,MA,1977.
[19]王建华,韩红艳,王春平,朱元昌。CCD双目立体视觉测量系统的理论研究。电光与控制,2007,14(4):94-96.
[20]叶海加,陈罡,邢渊.双目CCD结构光三维测量系统中的立体匹配J.光学精密工程,2004,12:71-75.
[21]管业鹏,顾伟康.基于双目视觉的基准差梯度立体匹配法J.传感技术学报,2004,3:74-77。
[22]朱效明,高稚允.双CCD立体视觉系统的理论研究J.光学技术,2003,29:298-300.
[23]A simple algorithm for shape from shading In IEEE Proceedings of Computer Vision and Pattern Recognition,1922,459-465.
[24]A.Blake and A.Zisserman.Surface descriptions from stereo and shading.Image and Visio Computing,1985;3(2):183-191.
[25]傅爽,王蕴珊,韩广兵.基于小波数字滤波的傅里叶变换轮廓法,光电子·激光,2004,15(2):205-207.
[26]S Mallat,WL Hwang.Singularity detection and processing with wavelets[J].IEEE Transaction on Information Theory,1992,38 2:617-643.
[27].Okada K,Sato A,Tsujiuchi J.Simultaneous calculation of phase distribution and scanning phase shift in pahse shifting inerferometry[J].Opt.Commun,1991;84:118-124.
[28].Z Wang,B Han Advanced iterative algorithm for randomly phase-shifted interferograms with intra- and inter-frame intensity variations.Opt.Las Eng 2007;45:274-280.
[29].H.Miao,C.Quan,C.J.Tay and Y.Fu.Analysis of phase distortion in phase-shifted fringe projection.Opt Lasers Eng 2007;45:318-325.
[30].Adam Styk,Krzysztof Patorski.Identification of nonlinear recording error in phase shifting interferometry.Opt.Lasers Eng,2007,45:265-273.
[31].Harmeet Singh and James S.Sirkis.Direct extraction of phase gradients form Fourier-transform and phase-step fringe patterns.Appl.Opt,1994,33(22),5016-5020.
[32]陈文艺,谭玉山。调相光栅的正交相干相位检测.光学光报,1990,10(12):1102-1106。
[33]S.T.Tang,Y.Y Hung.Fast profilometer for the automatic measurement of 3-D object shapes.Appl.Opt.1990,29(20):3012-3018.
[34]X.Zhou,X.Y.Su.Effect of the modulation transfer function of a digital image-acquisition deviceon phase-measuring profilometry.Appl.Opt,1994,33(35):8210-8215.
[35]GT Reid,RC Rixon,H.I.Messer.Absolute and comparative measurements of three-dimensional shape by phase measuring moire topography.Optics and laser technology,1984,16:315-319.
[36]苏显渝,李继陶.信息光学[M],p321-335.
[37]Z Wang,B Han.Advanced iterative algorithm for randomly phase-shifted interferograms with intra-and inter-frame intensity variations.Opt.Lasers Eng 2007;45:274-280.
[38]OkadaK,SatoA,TsujiuchiJ.Simultaneous calculation of phase distribution and scanning phase shift in phase shifting in terferometry.Opt.Commun.1991,84:118-124.
[39]GS Han,SW Kim.Numerical correction of reference phases in phase-shifting interferometry by iterative least-square fitting.Appl.Opt,1994,33:7321-7325.
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