Fig. 2

Trade-off curve between the weighted residual norm, \(\left\| {\mathop \varSigma \nolimits_{d}^{{ - {1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-0pt} 2}}} (\varvec{d} - \varvec{Gs})} \right\|\), and the roughness norm of the slip distribution, \(\left\| {\varvec{Ls}} \right\|\), represented by the green line. The blue star marked by point A is the smoothing parameter of 0.2 obtained from the ABIC-based method. The red star marked by point B is the optimal value of 15.0 for the smoothing parameter obtained by measuring the minimum distance from the curve to the origin of the figure after normalization of both the weighted residual norm and the roughness norm of the slip. The black star marked by point C is the value of 700.0 determined for the smoothing parameter, which was selected to show the over-smoothed result