Top panel: full map on the plane of the sky (x̂ŷ plane) of the line-of-sight visual extinction. Bottom panel: alignment size along the line of sight (x̂ẑ plane). We adopt n₀ = 5 × 10⁵ cm^-3, r_flat = 0.024 pc, α = 2, U₀ = 1, γ = 0.3, oblate grains (axial ratio of 1.4) with a_max = 1 μm, β = -3.5, and f_max = 1. This setup mimics the scale of the Pipe-109 starless core, whose data will be used later in this work.