Open loops traced in 3D solar coronal coordinates at points 4, 5 (panels a and b) and 6, 7 (panels c and d). The grey planes represent epipolar planes crossing the loops at the points under observation. The epipolar planes are formed in the heliosphere by the two spacecraft locations and each of the points 4, 5, 6, and 7; v_ep is reconstructed in the plane as shown in Fig. 8. The V_3D velocity vectors are reconstructed using the measured angle β and v_ep according to Eq. (1). The magnitudes of the vectors are shown in Table 2.