Figure 2

2D Lagrangian surface strain estimation. (a) RV surface image with superimposed mid-line points (white dots) representing the partitions. All possible vector configurations are shown for a chosen point (C) using mid-line points (A)bove, (B)elow, to the (L)eft and to the (R)ight. (b, c) Pre- and post-deformation, respectively, for a single vector configuration. Strain for the chosen point C is calculated using the configuration of points above and to the right (ACR). V ₁ and V ₂ represent the co-planar vectors formed. V ₃ represents the orthogonal unit vector calculated from the cross product of V ₁ and V ₂ . V' ₁ and V' ₂ represent the corresponding post deformation co-planar vectors, and V' ₃ is the cross product of V' ₁ and V' ₂ .