  Upcoming VLBI observations will resolve nearby supermassive black holes, most
notably Sagittarius A* and M87, on event horizon-scales. Recent observations of
Sagittarius A* with the Event Horizon Telescope have revealed horizon-scale
structure. Accordingly, the detection and measurement of the back hole
``shadow" is expected to enable the existence of astrophysical black holes to
be verified directly. Although the theoretical description of the shadow is
straightforward, its observational appearance is largely determined by the
properties of the surrounding accretion flow, which is highly turbulent. We
introduce a new polarised general-relativistic radiative transfer code,
\texttt{BHOSS}, which accurately solves the equations of polarised radiative
transfer in arbitrary strong-gravity environments, providing
physically-realistic images of astrophysical black holes on event
horizon-scales, as well as also providing insight into the fundamental
properties and nature of the surrounding accretion flow environment.
