| 摘要 |
An angular detection arrangement for a head mountable display (HMD) comprising a light source or reflective marking and an optical detector, one of the light source or reflective marking and the optical detector being disposed at the HMD and the other being disposed at a fixed point, the light source or reflective marking comprising a directional light source or reflective marking and a substantially non-directional light source or reflective marking such that the separation between the directional and non-directional light sources or reflective markings as detected at the optical detector is dependent upon the relative orientation of the HMD and the fixed point. |
