  Radiation transfer is an important topic in several physical disciplines,
probably most prominently in astrophysics. Computer scientists use radiation
transfer, among other things, for the visualisation of complex data sets with
direct volume rendering. In this note, I point out the connection between
physical radiation transfer and volume rendering, and I describe an
implementation of direct volume rendering in the astrophysical radiation
transfer code RADMC-3D. I show examples for the use of this module on
analytical models and simulation data.
