a, Processing tree. Number of particles in a particular class is reported above the density. Densities used for further processing are coloured as in Fig. 1a. b, Final composite map created from the focused refined maps. c, Local resolution estimate for the composite map. d, Fourier shell correlation plots for all focused refined maps and the composite map. e, Angular distribution plot for the high-resolution Pol II class used as a starting point for focused classifications.