`Nulling´ filters and the separation of transparent motions

Using low-order global motion hypotheses and the assumption that there are no more than two motions at a single point, it is possible to successfully decompose motion stimuli that contain additively combined transparent layers. It is assumed that the space of flow fields is sufficiently smooth that a relatively coarse sampling of the flow parameter(s) will produce a set of vector fields that can be combined to reasonably approximate the actual motions in the scene. The definition of support from an exclusively spatial notion is extended to include the spatio-temporal energy domain. The key insight is that when processing transparent motion displays, the support of a motion hypothesis should exist over both a region of space and velocity, so that it can be isolated both spatially and in terms of local velocity