HDF5 File Structure, where each blue node represents a HDF5 group and red nodes are datasets. The data file contains general galaxy parameters under the /Galaxies/Attributes group such as the SubhaloID in the simulation or the total mass of stars particles M_⋆. The images of particles in the different fields (i.e metallicity, mass, stellar age) are calculated in two and three dimensions and saved under the respective subgroup.