Emergent flux profiles of an intermediate (k_L = 10³, top panel) and strong (k_L = 10⁵, bottom panel) line. The blue, red, and green curves correspond to the solution of the FVM, SClin, and SCbez methods, respectively. The reference profile (black solid line) has been derived from the “exact” 1D source function interpolated onto the 3D Cartesian grid. Corresponding relative and absolute errors are shown at the bottom of each chart. For all profiles, the continuum level has been determined from a zero-opacity model.