An Invariant Representation for Matching Trajectories Across Uncalibrated Video Streams

Abstract. We introduce a view–point invariant representation of moving object trajectories that can be used in video database applications. It is assumed that trajectories lie on a surface that can be locally approximated with a plane. Raw trajectory data is first locally–approximated with a cubic spline via least squares fitting. For each sampled point of the obtained curve, a projective invariant feature is computed using a small number of points in its neighborhood. The resulting sequence of invariant features computed along the entire trajectory forms the view– invariant descriptor of the trajectory itself. Time parametrization has been exploited to compute cross ratios without ambiguity due to point ordering. Similarity between descriptors of different trajectories is measured with a distance that takes into account the statistical properties of the cross ratio, and its symmetry with respect to the point at infinity. In experiments, an overall correct classification rat...

• Type: Conference
• Year: 2005
• Where: CIVR
• Authors: Walter Nunziati, Stan Sclaroff, Alberto Del Bimbo
• Keywords: CIVR 2005, Invariant Features, Trajectories, View–point Invariant Representation