1. A method of detecting an attention of an occupant of a vehicle, comprising: calculating, by a processor, a first gaze vector in a three-dimensional space based on a first vehicle location, a first vehicle orientation, and a first gaze direction; calculating, by the processor, a second gaze vector in the three-dimensional space based on a second vehicle location, a second vehicle orientation, and a second gaze direction; and determining the attention of the occupant based on the first gaze vector and the second gaze vector.