(a) Points 1 to 7 on Image 1 selected for triangulation. (b) Points 1 to 7 on Image 2 are found on the corresponding epipolar lines (dashed lines) at the intersection with the observed structures. Points 1, 2, and 3 belong to closed loops (i.e. where both of their bases can be identified in AIA EUV images); whereas points 4, 5, 6, and 7 belong to open loops (i.e. where only one of their bases can be identified AIA EUV images). To validate the tie-pointing procedure the reverse process was performed, first starting from the obtained points in Image 2 (panel d) and then selecting their stereoscopic pairs on the corresponding epipolar lines in Image 1 (panel c), obtaining the same points.