tps2d is the core function for Thin Plate Splines. It is used internally for
all TPS graphical functions.tps_apply is the very same function but with
arguments properly named (I maintain tps2d as it is for historical reasons) when
we want a apply a trasnformation grid.tps2d(grid0, fr, to)tps_apply(fr, to, new)
(x; y) coordinates with TPS-interpolated
deformationstps_arr,
tps_grid, tps_iso,
tps_raw