Comparison of H_α and Fe I line profiles computed with M3DIS, but with different spatial resolutions used in 3D RHD model calculations (left column) and in the post-processing spectrum synthesis (right column). For the results presented on the left-hand side, we adopt models C and D from Table 2, respectively, where D (N_x × N_y × N_z) = (300, 300, 150) is our reference. For the results presented on the right-hand side, we use 3 characteristic spatial resolutions that differ only in horizontal resolution of (N_x × N_y) = (10, 10) (low – res.), (30, 30) (med. – res.), and (80, 80) (high – res.). For Fe I, we also show for comparison the profile computed a very high horizontal resolution of (150, 150) in spectral synthesis. See text.