A Heuristic Coordinate Filtering Scheme to Aid Online Indexing of Spatio-Temporal Trajectories

Traditional online indexing of spatio-temporal trajectories requires indexing coordinates at fixed intervals or each time the moving object changes direction or velocity. We propose a heuristic coordinate filtering scheme to help evaluate each periodically sampled coordinate candidacy for indexing. Successful coordinates are the minimum trajectory´s coordinates required as control points during the cubic spline interpolation process; invoked whenever a spatio-temporal historical query is made on the indexed trajectory. Using our heuristic coordinate filtering scheme, the number of indexed coordinates is significantly reduced to 25% - 35% of the original amount required by the traditional indexing methods, yet the indexed trajectory´s integrity is well preserved. Both heuristic coordinate filtering and cubic spline interpolation step require minimal time penalty, hence allowing our method for online uses.