Filtered versions of the Herschel column density maps of L1688 (top) and L1689 (bottom), where the contrast of filamentary structures has been enhanced by accumulating small-scale emission up to a transverse scale of 150′′ (~ 0.1 pc) using the getfilaments algorithm (see Sect. 4.3). The grayscale represents effective column density within the skeleton masks generated by getfilaments. The skeleton of the filaments independently extracted with the DisPerSE algorithm is displayed in yellow. Top panel: the red star marks the center of mass of L1688.