1. A method comprising: detecting a head with a first camera of a plurality of cameras, the head as detected with the first camera being captured in a first detected head image associated with the first camera; registering a head model with the first detected head image; detecting the head with a second camera of the plurality of cameras, the head as detected with the second camera being captured in a second detected head image associated with the second camera, a geometry between the cameras being uncalibrated; back-projecting the second detected head image to the head model; determining the geometry between the cameras; and determining a head pose of the head from the second detected head image as back-projected to the head model.