  Elliptic flow and HBT are studied for non-central relativistic nuclear
collisions. Azimuthal asymmetries show up in both elliptic flow and HBT radii
and are calculated in both collisionless and hydrodynamic limits relevant for
peripheral and central collisions respectively. Determining the reaction plane
and measuring the HBT radii as function of the angle between the reaction plane
and the particle momenta can determine the physical quantities as source sizes,
deformations, emission times, duration of emission and opacities. Comparison to
SPS data and predictions for RHIC and LHC energies are given. The centrality
dependence with and without a phase transition to a quark-gluon plasma is
discussed - in particular, how the physical quantities are expected to display
a qualitative different behavior in case of a phase transition.
