This is from an experiment I made for my thesis in the field of nonlinear elasticity. It is a thin wooden beam fixed on one end. Force is applied trough a rubber band on the other end. The amount of force is determined from it's current length and a separate stiffness experiment. The curves were extracted from several pictures using openCV machine vision library and afterwards approximated by parametric 8-degree polynomials in x and y directions. Software was scripted in Python2 and image processing was done in Gimp.