A Hybrid (Monte-Carlo/Deterministic) Approach for Multi-Dimensional   Radiation Transport
  A novel hybrid Monte Carlo transport scheme is demonstrated in a scene with solar illumination, scattering and absorbing 2D atmosphere, a textured reflecting mountain, and a small detector located in the sky (mounted on a satellite or a airplane). It uses a deterministic approximation of an adjoint transport solution to reduce variance, computed quickly by ignoring atmospheric interactions. This allows significant variance and computational cost reductions when the atmospheric scattering and absorption coefficient are small. When combined with an atmospheric photon-redirection scheme, significant variance reduction (equivalently acceleration) is achieved in the presence of atmospheric interactions. 
Guillaume Bal, Anthony Davis, and Ian Langmore
math-ph math.MP physics.ao-ph physics.comp-ph