1. A computer-implemented method for processing video image data, the method comprising: detecting a plurality of objects in the video image data; and for each object: generating, via a processor, a primitive event symbol stream identifying one or more primitive events engaged in by the object, wherein each primitive event represents a behavior engaged in by the object, generating, via the processor, a phase-space symbol stream representing quantitative characteristics of the object, wherein the phase-space symbol stream for the object indicates a trajectory of that object in the video image data over time, and combining, via the processor, the primitive event symbol stream and the phase-space symbol stream to generate a vector representation of the behavior engaged in by the object as depicted in the video image data.