Maps showing the equivalence |$\rm rCf$| topographies in 2-D principal component space for the synthetic data cases. Maps are produced using the first two components and corresponding |$\rm rCf$| values. In the Cases 3 and 4, true model parameters are added into the last column of matrix M and their |$\rm rCf$| values are added to the end of the misfit vector. Smoothed contour lines are used for better illustrations.