  We present a detailed study of an earth-directed coronal mass ejection (Full
halo CME) event happened on 2011 February 15 making use of white light
observations by three coronagraphs and radio observations by Wind/WAVES. We
applied three different methods to reconstruct the propagation direction and
traveling distance of the CME and its driven shock. We measured the kinematics
of the CME leading edge from white light images observed by STEREO A and B,
tracked the CME-driven shock using the frequency drift observed by Wind/WAVES
together with an interplanetary density model, and obtained the equivalent
scattering centers of the CME by Polarization Ratio(PR) method. For the first
time, we applied PR method to different features distinguished from LASCO/C2
polarimetric observations and calculated their projections onto white light
images observed by STEREO A and B. By combining the graduated cylindrical shell
(GCS) forward modeling with the PR method, we proposed a new GCS-PR method to
derive 3D parameters of a CME observed from a single perspective at Earth.
Comparisons between different methods show a good degree of consistence in the
derived 3D results.
