1. A method of determining a 3D trajectory of an object from at least two observed trajectories of the object in a scene, there being at least one unobserved trajectory of the object between the at least two observed trajectories, said at least two observed trajectories being captured in a series of images by at least one camera, each of the images in the series being associated with one of first and second poses of the at least one camera, said method comprising the steps of: selecting first and second points on the object from separate parallel planes of the scene for establishing a set of 2D capture locations; determining, from the series of captured images of the first pose of the at least one camera, a first set of 2D capture locations corresponding to the first point and a second set of 2D capture locations corresponding to the second point; determining, from the series of captured images of the second pose of the camera, a third set of 2D capture locations corresponding to the first point and a fourth set of 2D capture locations corresponding to the second point; reconstructing, relative to the first pose of the at least one camera and the second pose of the at least one camera, a first approximated 3D trajectory from the first set of 2D capture locations and the third set of 2D capture locations in the scene based on a spatial consistency of the first set of 2D capture locations and the third set of 2D capture locations and at least one unobserved location corresponding to the first point between the first set of 2D capture locations and the third set of 2D capture locations; reconstructing, relative to the first pose of the at least one camera and the second pose of the at least one camera, a second approximated 3D trajectory from the second set of 2D capture locations and the fourth set of 2D capture locations in the scene based on a spatial consistency of the second set of 2D capture locations and the fourth set of 2D capture locations and at least one unobserved location corresponding to the second point between the second set of 2D capture locations and the fourth set of 2D capture locations; and determining the 3D trajectory of the object based on the first and second approximated 3D trajectories, the determined 3D trajectory representing 3D locational information of the object when moving along the at least two observed trajectories and the at least one unobserved trajectory.