The motion of targets is well known to result in their defocussing and
displacement in SAR imagery, but detection of motion and re-focussing of
targets under generic conditions remains of ongoing interest. One class
of methods involves forming images of sub-apertures in which motion
defocussing will be reduced. In this paper, we use dynamic tomographic
image formation methods utilising an optical flow constraint to form a
video of SAR sub-aperture images. These retain fine resolution of the
full aperture, focussing along-track motion.