The Generic Structure of the Optic Flow Field

The optic flow field is defined such that along integral lines of the field the image intensity remains constant. For each time instance in an image sequence poles are created in the optic flow field at the position of spatial image singularities. We describe the generic flow singularities and the generic transitions of these over time. For classic analytic flow fields the classification of the generic topology is based on points of vanishing flow which can be further subdivided into repellers, attractors, whirls, and combinations hereof. We point out the resemblance, but also the important differences between the structure of the classical analytic flow field, and the structure of the optic flow field expressed through its normal flow. We conclude by giving a operational scheme for the detection of these singularities and events; and apply the scheme to two different examples within attention mechanism and the degree of turbulence in a flow field respectively.