Linearity s₂₂ and sparsity s₂₁ of optical, FIR, and MIR cirrus maps with different (j₁, j₂) combinations, which are summary statistics quantifying the non-Gaussianity of density fluctuations in the field. The structure scale is color-coded by j₁. The coherence scale j₂ characterizes the clustering on a scale j₂ of j₁-scale patterns. Only j₂ > j₁ terms are shown because j₂ ≤ j₁ terms are not physically significant. Values of s₂₂ > 1 correspond to thin, filamentary structures, whereas values of s₂₂ < 1 correspond to swirly, curvy structures. Lower s₂₁ indicates that the structures are more widely spread, whereas s₂₁ = 0 is the expectation for a Gaussian random field. In general, s₂₂ and s₂₁ of optical, FIR, and MIR cirrus maps have similar patterns except for small-scale structures.