Change default isolevels
This MR changes the default levels of the isosurface to logspace(log10(Imin), log10(Imax), N)[1:-1] with N=4
It caches them to avoid computing min/max multiple times
This MR changes the default levels of the isosurface to logspace(log10(Imin), log10(Imax), N)[1:-1] with N=4
It caches them to avoid computing min/max multiple times