Spatial distribution of filamentary structures in gnomonic projection. The field size is 27°.7. Top: isolated filamentary structures discussed in the text. For each position, the color coding shows weights according to the number of neighbors n_Neighbor inside the filament. Boundary pixels n_Pout just outside the filaments have weight −1 and are coded in blue. Bottom: velocity field of the filamentary structures, including all other filaments in the field. The center position is l = 260°, b = 58°.