  We combine a Monte Carlo radiative transfer code with an SPH code, so that --
assuming thermal equilibrium -- we can calculate dust-temperature fields,
spectral energy distributions, and isophotal maps, for the individual
time-frames generated by an SPH simulation. On large scales, the radiative
transfer cells (RT cells) are borrowed from the tree structure built by the SPH
code, and are chosen so that their size -- and hence the resolution of the
calculated temperature field -- is comparable with the resolution of the
density field. We refer collectively to these cubic RT cells as the 'global
grid'. The code is tested and found to treat externally illuminated dust
configurations very well. However, when there are embedded discrete sources,
i.e. stars, these produce very steep local temperature gradients which can only
be modelled properly if -- in the immediate vicinity of, and centred on, each
embedded star -- we supplement the global grid with a 'star grid' of closely
spaced concentric RT cells.
