  From the beginning the Geant4 Visualisation System was designed to support
several simultaneous graphics systems written to common abstract interfaces.
Today it has matured into a powerful diagnostic and presentational tool. It
comes with a library of models that may be added to the current scene and which
include the representation of the Geant4 geometry hierarchy, simulated
trajectories and user-written hits and digitisations. The workhorse is the
OpenGL suite of drivers for X, Xm, Qt and Win32. There is an Open Inventor
driver. Scenes can be exported in special graphics formats for offline viewing
in the DAWN, VRML, HepRApp and gMocren browsers. PostScript can be generated
through OpenGL, Open Inventor, DAWN and HepRApp. Geant4's own tracking
algorithms are used by the Ray Tracer. Not all drivers support all features but
all drivers bring added functionality of some sort. This paper describes the
interfaces and details the individual drivers.
