In general VTK is a very versatile format, which allows many possible structures. For information on the generic VTK format, please visit the official VTK website. This page describes only SMASH-specific VTK format.

SMASH VTK files contain a snapshot of the simulation for a certain output time step. VTK output files are written at the initialization of an event, i.e. the starting time of an event, and at every output time step specified by either Output_Interval or Output_Times. For every output time step a separate VTK file is written. File names are constructed as follows: pos_ev<event>_ens<ensemble>_tstep<timestep_counter>.vtk.

Files contain particle coordinates, momenta, PDG codes, cross-section scaling factors, information if a particle is already formed, ID, number of collisions, baryon number, strangeness, and masses. VTK output is known to work with ParaView, a free visualization and data analysis software. Files of this format are supposed to be used as a black box and opened with ParaView, but at the same time they are human-readable text files.

There is also a possibility to print a lattice with thermodynamical quantities to VTK files, see Thermodynamics VTK output.