Interpolated values of the optical depth inside a single cell, based on Eq. (9), along each direction $\widehat{\mathbf{\Omega }}$. In this example, the values of the optical depth in the directions x⁺, x⁻, y⁺, y⁻, $z^{+},z^{-},d_{x\mathit{y}}^{+},d_{x\mathit{y}}^{-},{\overline{d^{+}}}_{x\mathit{y}},{\overline{d^{-}}}_{x\mathit{y}},d_{\mathit{xz}}^{+},d_{\mathit{xz}}^{-},{\overline{d^{+}}}_{\mathit{xz}},{\overline{d^{-}}}_{\mathit{xz}},d_{\mathit{y}z}^{+},d_{\mathit{y}z}^{-},{\overline{d^{+}}}_{\mathit{y}z}$ and ${\overline{d^{-}}}_{\mathit{y}z}$ are equal to 14, 7, 6, 0.5, 7, 5, 2, 1.5, 5, 13, 9, 6, 9, 8, 4, 3, 10 and 3, respectively.