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| Comparison of Three Sub-pixel Displacement Algorithm |
| ZI Xin-yun1,GENG Shuai1,ZHAO Shu-fan1,XIA Jun-jian1,SHU Fang2 |
1.Engineering Experiment Center, Military Transportation University, Tianjin 300161, China;
2.Institute of Technology, Tianjin University of Finance, Tianjin 300222, China |
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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.
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2015, Vol. 36 
