A controller obtains a distance index associated with first and second cameras and a camera distance between the first and second cameras. The controller receives a first and second image captured by the first and second cameras, respectively. The first and second images include a first and second object image of an object, respectively. The controller calculates a first object distance between the first camera and the object using a distance index associated with the first and second cameras, the camera distance, the first object image, and the second object image. The controller calculates an object real size of the object using the first object distance, the second object image, the camera distance, and the distance index. The controller determines whether policy criteria are satisfied by the first object distance and/or the object real size. When satisfied, the controller performs an action associated with the criteria.