Longitude-velocity (lv) diagrams of CO mean intensity (⟨I⟩ , left) and filament orientation anisotropy quantified by the projected Rayleigh statistic (V, right). Each pixel element in the diagrams corresponds to a 10^° × 10^° × 1.29 km s⁻¹ velocity-channel map centered on b = 0^°, referred to as a tile throughout this paper. Results correspond to the Hessian analysis using an 18^′ FHWM derivative kernel. Values of V > 0 (red) or V < 0 (blue) indicate a preferential orientation of the filaments parallel (θ = 0^°) or perpendicular (θ = 90^°) to the Galactic plane. The 3σ statistical significance for these two orientations corresponds to V > 2.87 or V < −2.87, respectively. The overlaid curves correspond to the main spiral arms features presented in Reid et al. (2016), the outer Scutum-Centaurus arm (OSC, Dame & Thaddeus 2011), and the extended outer arm (M-G2004, McClure-Griffiths et al. 2004).