  We analyze multi-spacecraft observations of a giant filament eruption that
occurred during 26 and 27 September 2009. The filament eruption was associated
with a relatively slow coronal mass ejection (CME). The filament consisted of a
large and a small part, both parts erupted nearly simultaneously. Here we focus
on the eruption associated with the larger part of the filament. The STEREO
satellites were separated by about 117 degree during this event, so we
additionally used SoHO/EIT and CORONAS/TESIS observations as a third eye (Earth
view) to aid our measurements. We measure the plane-of-sky trajectory of the
filament as seen from STEREO-A and TESIS view-points. Using a simple
trigonometric relation, we then use these measurements to estimate the true
direction of propagation of the filament which allows us to derive the true
R=R_sun v/s time profile of the filament apex. Furthermore, we develop a new
tomographic method that can potentially provide a more robust three-dimensional
reconstruction by exploiting multiple simultaneous views. We apply this method
also to investigate the 3D evolution of the top part of filament. We expect
this method to be useful when SDO and STEREO observations are combined. We then
analyze the kinematics of the eruptive filament during its rapid acceleration
phase by fitting different functional forms to the height-time data derived
from the two methods. We find that, for both methods, an exponential function
fits the rise profile of the filament slightly better than parabolic or cubic
functions. Finally, we confront these results with the predictions of
theoretical eruption models.
