In order to remove the epipolar ambiguity, we utilize a
second geometric constraint: the scene structure in the Euclidean
world coordinate system remains constant. This
structure consistency constraint is implemented within a
“Plane+Parallax” framework [6, 10, 12] which represents
the scene structure by a 2D residual displacement (parallax)
field w.r.t. a 3D reference plane. The magnitude of each
parallax displacement is directly related to projective structure,
i.e. relative depth. If a pair of 2D points correspond
to the same static 3D point, their relative depths are constrained
by the structure consistency. The deviation from
this constraint indicates that the point belongs to an independently
moving object. This provides an additional cue
for pixel classification.