Sample hull for a single point from a GPS dataset. Similarly colored points represent continuity in time. The parent-point is shown by a triangle; nearest neighbours identified using TSD with s= 0.1 are circled. Non-circled points within the hull are closer to the parent point but were bypassed as nearest neighbours due to their distance in time. The ellipse outlined in red is the bounding ellipse whose eccentricity is one of the metrics of hull elongation.