An invention for identifying a spatial location of an event within video image data is provided. Disclosed are embodiments for generating trajectory data of a trajectory of an object for a plurality of pixel regions of an area of interest within video image data, the generating comprising: identifying one or more pixel regions from the plurality of pixel regions containing trajectory data; performing a multi-point neighborhood scan within the one or more pixel regions from the plurality of pixel regions containing trajectory data; and generating a transition chain code based on the multi-point neighborhood scan. Embodiments further generate a set of compressed spatial representations of the trajectory data of the trajectory of the object for an event based on the transition chain code, and generate a lossless contour code of the trajectory data of the trajectory of the object for the event based on the transition chain code.