Head-mountable apparatus and systems

摘要

A head mountable display (HMD) 510 has an upward facing camera 520 associated with a wide angle (such as a fisheye) lens 500 arranged to capture images of the environment of the HMD. An indication of yaw is derived from images captured by the upward facing camera 520 at different points in time. The images may be successively captured images. An image warping process may be applied to convert the captured images into a linear image format. The HMD 510 may comprise a processor configured to identify feature points in the different images and to detect the positions in the images of the feature points so as to provide an indication of rotational movement of the HMD between two images.