System and method of classifying an action or event

A method of classifying an action or event using an artificial neural network. The method comprises obtaining a first and a second plurality of feature responses, corresponding to point data in a first channel and a second channel respectively. Each of the first and second plurality of feature responses have associated temporal and spatial position values, the first and second plurality of feature responses relating to a plurality of objects. The method also comprises generating a third plurality of feature responses based on one of the first plurality of feature responses and one of the second plurality of feature responses, and a weighted combination of associated temporal and spatial position values of the corresponding one of the first and second plurality of feature responses; and classifying an action or event relating to the objects using the artificial neural network based on the third plurality of feature responses.