1. A system for identifying a target object that is displayed on a screen, the system comprising at least one processor that: determines a position of a first body part of a user using a first video frame from a camera; determines a position of a second body part of the user using the first video frame; identifies a region of a screen based on the position of the first body part and the position of the second body part; identifies a target object, from among graphical objects displayed on the screen, that corresponds to the region on the screen; identifies a first point on an image plane associated with the camera, wherein the first point corresponds to a location of the second body part along a calibration sight line between the first body part and a calibration object displayed on the screen; identifies a second point on the image plane, wherein the second point corresponds to a location of the second body part along a target sight line between the first body part and a target point on the screen; identifies a third point on a second plane that corresponds to the second point on the image plane, wherein the second plane is parallel to the screen and intersects the image plane; identifies a fourth point on the second plane that corresponds to the first point on the image plane; determines a scaling factor based on a position of the calibration object relative to a position of the camera, and further based on a location of the fourth point on the second plane; and identifies the target object based on the scaling factor and the location of the third point on the second plane.