  Two optical flow estimation problems are addressed: i) occlusion estimation
and handling, and ii) estimation from image sequences longer than two frames.
The proposed ContinualFlow method estimates occlusions before flow, avoiding
the use of flow corrupted by occlusions for their estimation. We show that
providing occlusion masks as an additional input to flow estimation improves
the standard performance metric by more than 25\% on both KITTI and Sintel. As
a second contribution, a novel method for incorporating information from past
frames into flow estimation is introduced. The previous frame flow serves as an
input to occlusion estimation and as a prior in occluded regions, i.e. those
without visual correspondences. By continually using the previous frame flow,
ContinualFlow performance improves further by 18\% on KITTI and 7\% on Sintel,
achieving top performance on KITTI and Sintel.
