Fig. 1. Results of the experiment 1. (a) Theoretical displacement v; (b) theoretical strain field v_x; (c) theoretical strain field v_y

Fig. 2. Displacement field under different noise levels. (a) Reference image with 1% noise; (b) deformed image with 1% noise; (c) DIC displacement field v with 1% noise; (d) DIC displacement field v with 2% noise; (e) DIC displacement field v with 3% noise

Fig. 3. E_RMS of strain field calculated by three methods. (a) Noise is 1%; (b) noise is 2%; (c) noise is 3%

Fig. 4. Reference image, deformed image and DIC displacement. u₁ deformation: (a) Reference image(u₁); (b) deformed image (u₁); (c) DIC displacement (u₁); (d) reference image (u₂); (e) deformed image (u₂); (f) DIC displacement (u₂)

Fig. 5. E_RMS of PLS method and SSA under different displacement fields and noise conditions. (a) u₁ deformation; (b) u₂ deformation

Fig. 6. SMA experiment. (a) Reference image; (b) deformed image; (c) DIC displacement

Fig. 7. Strain values calculated by PLS method and SSA