The Angular Velocity Associated with the Optical Flowfield Arising from Motion through a Rigid Environment

The instantaneous optical flowfield due to a camera moving through a rigid environment may be compatible with up to three distinct values for the angular velocity, but three is the maximum number that can occur. Each angular velocity is associated with a particular set of relative depths of points in the environment. A method of constructing all flowfields compatible with more than one value of the angular velocity is given.