1. A method for detecting one or more events, comprising: using multiple overlapping regions of interest on a video sequence to cover a respective location for one or more events at a point of sale, wherein each event is associated with at least one of the multiple overlapping regions of interest; applying multiple-instance learning to the video sequence to select one or more of the multiple overlapping regions of interest to construct one or more location-aware event models, wherein applying multiple-instance learning comprises using a learning technique to learn the one or more location-aware event models for events including at least a pickup and a drop; and applying the models to the video sequence to detect the one or more events and to determine the one or more regions of interest that are associated with the one or more events.