Layered Representation for Motion Analysis
John Y. A. Wang and Edward H. Adelson
Proceedings of the IEEE Computer Society Conference on Computer Vision and Pattern Recognition
New York; June (1993).
Standard approaches to motion analysis assume that the optic flow
is smooth; such techniques have trouble dealing with occlusion
boundaries. The most popular solution is to allow discontinuities in
the flow field, imposing the smoothness constraint in a piecewise
fashion. But there is a sense in which the discontinuities in flow
are artifactual, resulting from the attempt to capture the motion of
multiple overlapping objects in a single flow field. Instead we can
decompose the image sequence into a set of overlapping layers, where
each layer's motion is described by a smooth flow field. The
discontinuities in the description are then attributed to object
opacities rather than to the flow itself, mirroring the structure of
the scene. We have devised a set of techniques for segmenting images
into coherently moving regions using affine motion analysis and
clustering techniques. We are able to decompose an image into a set
of layers along with information about occlusion and depth ordering.
We have applied the techniques to the ``flower garden'' sequence. We
can analyze the scene into four layers, and then represent the entire
30-frame sequence with a single image of each layer, along with
associated motion parameters.