The subject matter is to count the number of people in a large room, wherein a camera is placed in a very high ceiling: an example would be Grand Central Station. Faces are not visible: the scalp (top of the head) is visible to the camera as shown in the link's video.
The goal: I would like to perform a Google literature search to assess the work that has been performed on overhead head recognition, however, I am not sure what the best keyword pairs: (scalp? head? people?) to describe the object that is to be recognized from a camera positioned in the ceiling (overhead? bird's eye? satellite?). I'd like the search to return leading-edge (AI) techniques that benchmark results