1. A method of fitting and tracking a skeletal representation of an object within a three-dimensional scene represented by a three-dimensional point cloud, the skeletal representation comprising an arrangement of a plurality of control points, the method comprising the steps of: a) using the three-dimensional point cloud of the scene to determine input information relating to the object to be fitted and tracked within the scene; b) converting the determined three-dimensional point cloud of the object to be fitted and tracked into an orthographic representation; c) determining curvature centre points to estimate a central axis position of at least one part the object to be fitted and tracked using the orthographic representation; d) determining the position of the plurality of control points representing the object to be fitted and tracked within the three-dimensional scene using the orthographic representation; and e) fitting and tracking the plurality of control points within the three-dimensional scene using the orthographic representation to refine the position of the skeletal representation of the object with respect to time.