Region LHA 120-N 70 in Hα (a, logarithmic scale as in Table 1) and the corresponding ψ₂ Minkowski maps for window sizes of 40 px (~97 pc, b: absolute value, c: phase) and 100 px (242 pc, d: absolute value, e: phase). For the larger window size (right panels), the contributions from all sides of the bubble cancel each other out due to the phase rotation along the bubble. The phase at 100 px is thus dominated by the overall orientation of the bubble and the surrounding filaments.