Results for the infinite plane-parallel slab problem for transverse optical depths τ_max ∈ {75,150,300}. Different advanced MCRT methods (solid lines) are compared to results from a non-probabilistic numerical method (dotted lines). The forward label indicates a variant of the SePS method that differs only in its application of the Stretch method; it is applied if and only if the photon package scatters toward the detector.