“…For example, Discrete Fourier Transforms (DFT) (Faloutsos et al, 1994), Discrete Wavelet Transforms (DWT) (Chan & Fu, 1999), Adaptive Piecewise Constant Approximations (APCA) (Keogh et al, 2001), and Chebyshev polynomials (Cai & Ng, 2004) have been used to conduct similarity search in time series data. Previous work has also sought to represent moving object trajectories through piecewise linear or quadratic interpolation functions (Chang et al, 1998;Jeanin & Divakaran, 2001), motion histograms (Aghbari et al, 2003) or discretised direction-based schemes (Dagtas et al, 2000;Shim & Chang, 2001;. Spatiotemporal representations using piecewise-defined polynomials were proposed by (Hsu & Teng, 2002), although consistency in applying a trajectory-splitting scheme across query and searched trajectories can be problematic.…”