1. A method operable on a computer that is coupled to a memory containing video data of a prescribed physical area, the method responsive to the movement of objects in the prescribed physical area, the method comprising: identifying objects in the prescribed physical area by querying the video data, wherein the objects that are identified are moving in the prescribed physical area; generating a still image of the prescribed physical area; specifying by a user, a virtual line in the prescribed physical area, wherein the virtual line is superimposed on a user-selected portion of the still image of the prescribed physical area; determining a number of objects that cross the virtual line; and superimposing a representation of the number of objects on the user-selected portion of the still image.