Process of the filament eruption. (a1)–(a4): SDO/AIA 304 Å observations. (b1)–(b4): SDO/AIA 171 observations. The white box outlines the field of view of panels c1–c4. (c1)–(c4): NVST Hα observations. The blue arrows point out the erupting filament. The red and black contours indicate the positive and negative magnetic field with levels of ±100 G. The blue circles mark the brightenings associated with the footpoints of the inverted U-shaped filament. An animation available online shows the eruption process of the filament in 304 Å, and 171 Å wavelengths during the period from 07:12 UT to 07:52 UT.