梯度法、曲面拟合法和N-R法是数字散斑相关方法中提高位移测量精度的3种主要亚像素位移算法。研究了3种算法的原理并进行了数值模拟仿真。首先使用计算机模拟生成一系列位移为0.01 pixel的散斑图,并在生成的图像中添加方差不同的高斯噪声,对3种算法在噪声条件下的精度进行比较,结果显示在精度要求为0.01 pixel时,梯度法的噪声方差上限为0.006,N-R法的噪声方差上限为0.000 5,而曲面拟合法的计算精度具有较大不确定性,无法保证精度,梯度法更适用于工程应用。
Abstract
Gradient method, surface fitting and N-R method are 3 main sub-pixel displacement algorithms of digital speckle correlation method to improve the precision of the measuring system. The principles of three kinds of algorithm were studied and numerical simulation was carried out. To compare the different precision from 3 methods under noise, the computer models generate a series of speckle gram whose displacement is 0.01 pixels and different Gaussian noise was added in generated graphics. The results showed that in the precision requirement in 0.01 pixels, the upper bounds on noise variance of gradient method and N-R method are respectively 0.006 and 0.000 5, and the calculation precision of surface fitting method has huge uncertainty, gradient method is more suitable for engineering application.
关键词
计量学 /
数字散斑相关 /
曲面拟合 /
梯度法 /
N-R法 /
亚像素
Key words
Metrology /
Digital speckle correlation /
Quadratic surface fitting /
Gradient method /
N-R method /
Sub-pixel
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参考文献
［1］Peters W H, Ranson W F. Digital imaging techniques in experimental stress analysis［J］. Optical Engineering,1982, 21(3): 427-431.
［2］潘兵,谢惠民, 续伯钦,等.数字图像相关中的亚像素位移定位算法进展［J］.力学进展,2005,35(3):345-352.
［3］宋义敏,马少鹏,杨小彬,等.岩石变形破坏的数字散斑相关方法研究［J］.岩石力学与工程学报,2011,30(1): 170-175.
［4］Dong Y, Kakisawa H, Kagawa Y. Optical system for microscopic observation and strain measurement at high temperature［J］. Measurement Science and Technology, 2014, 25(2): 025002.
［5］俞海,郭荣鑫,夏海廷,等.数字图像相关法在WC/Cu复合材料线膨胀系数测量中的应用［J］. 光学精密工程, 2013, 21(10):2696-2703.
［6］Cofaru C, Philips W, Van Paepegem W. A novel speckle pattern—adaptive digital image correlation approach with robust strain calculation［J］. Optics and Lasers in Engineering, 2012, 50(2): 187-198.
［7］Sicard J, Sirohi J. Measurement of the deformation of an extremely flexible rotor blade using digital image correlation［J］. Measurement Science and Technology, 2013, 24(6): 065203.
［8］潘兵,续伯钦,陈丁,等.数字图像相关中亚像素位移测量的曲面拟合法［J］.计量学报, 2005,26(2): 128-134.
［9］潘兵,吴大方,谢惠民,等. 基于梯度的数字体图像相关方法测量物体内部变形［J］光学学报,2011,31(6):0612005
［10］Cofaru C, Philips W, Van Paepegem W. Improved Newton-Raphson digital image correlation method for full-field displacement and strain calculation［J］. Applied Optics, 2010, 49(33): 6472-6484.
［11］潘兵,谢惠民, 戴福隆. 数字图像相关中亚像素位移测量算法的研究［J］.力学学报,2007,39(2):245-252.
［12］Vendroux G, Knauss W G. Submicron deformation field measurements: Part 2. Improved digital image correlation［J］. Experimental Mechanics. 1998, 38(2): 86-92.
［13］Zhou P, Goodson K E. Sub-pixel displacement and deformation gradient measurement using digital image/speckle correlation ［J］. Optical Engineering, 2001,40(8):1613-1620.
［14］杨勇,王琰蕾,李明. 高精度数字图像相关测量系统及其技术研究［J］.光学学报,2006,26(2):197-201.
基金
国家863计划项目（2013AA065303）;国家自然科学基金（91120306）;天津市自然科学基金（14JCQNJC01600）
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