JCMT total intensity Stokes I map overlaid with polarization segments at 850 μm over the entire field of view (11’) of the JCMT. Blue segments show the polarization orientations with I > 5σ_I and P > 3σ_P, while green segments are I > 5σ_I and 3σ_P > P > 2σ_P. The lengths of the segments are proportional to $\sqrt{P}$. A reference scale bar of 5% is shown in the upper-left corner. The contours are 50, 500, and 1000 mJy beam⁻¹ for the total intensity. Orange contours are the boundaries of SDC18-N and SDC18-S at filament scale determined by the dendrogram analysis.