  Correlation functions, constructed from directional projections of the
relative velocities of fragments, are used to determine the shape of the
breakup volume in coordinate space. For central collisions of 129Xe + natSn at
50 MeV per nucleon incident energy, measured with the 4pi multi-detector INDRA
at GSI, a prolate shape aligned along the beam direction with an axis ratio of
1:0.7 is deduced. The sensitivity of the method is discussed in comparison with
conventional fragment-fragment velocity correlations.
