Comparison of subset-based local and FE-based global digital image correlation: Theoretical error analysis and validation
KAUST DepartmentPhysical Sciences and Engineering (PSE) Division
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AbstractSubset-based local and finite-element-based (FE-based) global digital image correlation (DIC) approaches are the two primary image matching algorithms widely used for full-field displacement mapping. Very recently, the performances of these different DIC approaches have been experimentally investigated using numerical and real-world experimental tests. The results have shown that in typical cases, where the subset (element) size is no less than a few pixels and the local deformation within a subset (element) can be well approximated by the adopted shape functions, the subset-based local DIC outperforms FE-based global DIC approaches because the former provides slightly smaller root-mean-square errors and offers much higher computation efficiency. Here we investigate the theoretical origin and lay a solid theoretical basis for the previous comparison. We assume that systematic errors due to imperfect intensity interpolation and undermatched shape functions are negligibly small, and perform a theoretical analysis of the random errors or standard deviation (SD) errors in the displacements measured by two local DIC approaches (i.e., a subset-based local DIC and an element-based local DIC) and two FE-based global DIC approaches (i.e., Q4-DIC and Q8-DIC). The equations that govern the random errors in the displacements measured by these local and global DIC approaches are theoretically derived. The correctness of the theoretically predicted SD errors is validated through numerical translation tests under various noise levels. We demonstrate that the SD errors induced by the Q4-element-based local DIC, the global Q4-DIC and the global Q8-DIC are 4, 1.8-2.2 and 1.2-1.6 times greater, respectively, than that associated with the subset-based local DIC, which is consistent with our conclusions from previous work. © 2016 Elsevier Ltd. All rights reserved.
CitationPan B, Wang B, Lubineau G (2016) Comparison of subset-based local and FE-based global digital image correlation: Theoretical error analysis and validation. Optics and Lasers in Engineering 82: 148–158. Available: http://dx.doi.org/10.1016/j.optlaseng.2016.02.019.
SponsorsThis work is supported by the National Natural Science Foundation of China (Grant nos. 11272032, 11322220 and 11427802), the science fund of State Key Laboratory of Automotive Safety and Energy (Grant no. KF16162) and the Beijing Nova Program (xx2014B034) and the opening fund of State Key Laboratory of Explosion Science and Technology. We also thank King Abdullah University of Science and Technology (KAUST) for its support.
JournalOptics and Lasers in Engineering