From left to right and top to bottom: (1) peak temperature of the raw C¹⁸O (J = 1−0) data; (2)integrated intensity of the multi-Gaussian fit result; (3) column density estimate derived from this integrated intensity and the dust temperature; (4) largest (in absolute value) eigenvalue ε₂ of the Hessian matrix computed at each point of the column density map; (5) regions identified as filamentary, by applying a threshold onto the ε₂ map; and (6) skeleton obtained by morphological thinning of these regions. The filaments that are eliminated at some point in the cleaning process are indicated in red.