Method and system for detecting shopping groups based on trajectory dynamics

The present invention is a method and system for detecting shopping groups based on the dynamic relation between shoppers' trajectories. First, shopper trajectories are generated using video images or positioning devices. Then, group behavior features are extracted from a candidate shopping group trajectory pair. The group behavior features of a given pair of trajectories are typically the changes in positional differences and the average speed of these trajectories. From a model of shopping group behavior, a given pair of candidate shopping group trajectories is analyzed to determine the group score—the likelihood of the pair of shoppers indeed belonging to the same group. Lastly, the system utilizes graph segmentation framework to find clusters where trajectories belonging to each cluster have tight group scores with each other.