Mean H I emission intensity (〈I〉) and projected Rayleigh statistic (V, Eq. (4)) for the 3° × 20° × 1.29 km s⁻¹ tiles. The colors indicate the tile percentage covered by the filamentary structures selected following the criteria described in Sect. 3.2. The horizontal dotted lines show V = ±2.87, which indicate the 3σ significance in the preferential orientation parallel, θ = 0°, or perpendicular, θ = 90°, to the Galactic plane, respectively. The vertical dashed line indicates the intensity threshold.