The eruptive structure in 3D and a comparison with SDO/AIA observation. (a) Side view of sampled magnetic field lines of the erupting MFR. The magnetic field lines are false-colored by the value of height z for a better visualization. The bottom surface is shown with the photospheric magnetogram. (b) Magnetic field lines that form the surface of the MFR (see the animated version of Figure 7 for a 3D rotation view of these field lines, as well as the 3D structure of the QSL). The view angle is arranged to be the same as that of the SDO. (c) SDO/AIA 94 Å observations of the eruption process. Two sets of arrows mark the two expanding edges, presumably corresponding to the expanding surface of the MFR. Such expanding features can be seen more clearly in the animated Figure 13.