The advent in recent years of robust, real-time, model-based tracking
techniques for rigid and non-rigid moving objects has made automated s
urveillance and event recognition a possibility. A statistically based
model of object trajectories is presented which is learnt from the ob
servation of long image sequences. Trajectory data is supplied by a tr
acker using Active Shape Models, from which a model of the distributio
n of typical trajectories is learnt. Experimental results are included
to show the generation of the model for trajectories within a pedestr
ian scene. We indicate how the resulting model can be used for the ide
ntification of atypical events.