Image coordinate of polarization swing along the spine (left column) and along the relevant limb (right column). For the top row, the black hole spin is fixed, and ﹩\tilde{\beta }﹩ (in units of M) is plotted as a function of γ_∞ and ﹩{\gamma }_{\infty }\sin i﹩. For the bottom row, inclination is fixed, and ﹩\tilde{\beta }﹩ is plotted as a function of black hole spin and ﹩{\gamma }_{\infty }\sin i﹩. Note that ﹩{\tilde{\beta }}_{{\rm{limb}}}﹩ diverges when ﹩{\gamma }_{\infty }\sin i=1﹩, which is demarcated with the upper black dashed line. The lower black dashed line marks the transition into the face-on regime, where the emission is viewed from within the cone of the jet and the projected limbs disappear from the image.