  We present a new method for determining the column density of erupting
filament material using state-of-the-art multi-wavelength imaging data. Much of
the prior work on filament/prominence structure can be divided between studies
that use a polychromatic approach with targeted campaign observations, and
those that use synoptic observations, frequently in only one or two
wavelengths. The superior time resolution, sensitivity and near-synchronicity
of data from the Solar Dynamics Observatory's Advanced Imaging Assembly allow
us to combine these two techniques using photo-ionisation continuum opacity to
determine the spatial distribution of hydrogen in filament material. We apply
the combined techniques to SDO/AIA observations of a filament which erupted
during the spectacular coronal mass ejection on 2011 June 07. The resulting
'polychromatic opacity imaging' method offers a powerful way to track partially
ionised gas as it erupts through the solar atmosphere on a regular basis,
without the need for co-ordinated observations, thereby readily offering
regular, realistic mass-distribution estimates for models of these erupting
structures.
