Fig. 1. Schematic of DIC method

Fig. 2. Flow chart of proposed method

Fig. 3. Schematic diagram of classical PLS algorithm

Fig. 4. Deformation test of computed-simulated speckle images. (a) A reference computed-simulated speckle image;(b) calculation result of the displacement field for homogeneous deformation in the ROI; (c) calculation result of the displacement field for inhomogeneous deformation in the ROI

Fig. 5. Comparison of root-mean-square error of strain fields calculated by three methods. (a) Homogeneous deformation; (b) inhomogeneous deformation

Fig. 6. Calculation results of strain fields of four methods under homogeneous deformation and inhomogeneous deformation. (a)(b) Classical PLS algorithm; (c)(d) proposed method-ewf; (e)(f) proposed method-pdf; (g)(h) RFE algorithm

Fig. 7. Calculation results of strain field of a plate with one hole. (a) Classical PLS algorithm; (b) proposed method-ewf; (c) proposed method-pdf; (d) RFE algorithm

Fig. 8. Comparison of strain mapped on line located in corresponding sub-image. (a) Horizontal strain; (b) shear strain; (c) vertical strain [inset: horizontal strain field, shear strain field, and vertical strain field calculated by proposed method-ewf with strain window size of 9×9(POI), from left to right]

Fig. 9. Results of vertical strain field of reinforced concrete column. (a) Vertical strain field calculated by classical PLS algorithm [strain window size: 15×15(POI)]; (b) vertical strain field calculated by proposed method-ewf [strain window size: 9×9(POI)]; (c) comparison of strain mapped on line located in corresponding sub-image of the two methods [inset: vertical strain field calculated by proposed method-ewf with strain window size of 9×9(POI)]

Table 1. Comparison of root-mean-square error of strain fields calculated by the three methods under homogeneous deformation

Table 2. Comparison of root-mean-square error of strain fields calculated by the three methods under inhomogeneous deformation

Table 3. Computational speed of three methods unit:point/s