Method and Apparatus for Tracking Motion of Objects in Three-Dimensional Space

A method and apparatus for tracking movement of an object in three-dimensional (3D) space uses a using a single sensor to capture images of the object moving through the 3D space. A change in change in position of the object in the 3D space is determined based on a change in size of the object in the images. The change in position is used to construct a trajectory of the object and the trajectory represents the movement of the object through the 3D space. Trajectories of a plurality of objects may be determined. The objects may be naturally occurring, or they may be manufactured and introduced into the 3D space. The determined trajectories may be used to characterize a flow field in the 3D space and produce an output comprising a 3D representation of the flow field.