This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
A head mounted display (HMD) is a display device, worn on the head that has a small display optic in front of the eyes. One use case for the head mounted display is ability to watch live of pre-recorded videos. Compared to traditional videos, when watching a 360 degree panoramic video with a head mounted display a user may be able to feel much more immersed inside the world of the video. Optional stereo effect in the video may enhance the immersive feeling even further.
A parallax can be regarded as a displacement or difference in the apparent position of an object when it is viewed along two different lines of sight. The parallax may be measured by the angle or semi-angle of inclination between those two lines. Parallax motion effect can be regarded as an apparent motion which objects may seem to take when an observer moves, or the observer rotates her/his head. For example, objects which are closer to the observer may seem to move faster than objects which are farther away from the observer.
360 degree stereo panorama videos are currently a common way to distribute three-dimensional (3D) videos meant to be viewed in head mounted displays. Viewing these videos may be an immersive experience, but even small glitches or shortcomings in the video playback may reduce the feeling of “presence” and may give the video artificial look. One such known issue in the 360 degree stereo panorama video format is the lack of the parallax motion effect when viewer rotates his/her head. This effect may be missing because the video streams for both eyes may be prestitched so that each object in the scene is seen from a fixed viewpoint. In real life when head is rotated the viewpoint moves slightly along the head and the foreground objects appear to move in relation to the background objects.
Currently, when 360 degree stereo panorama video is viewed in head mounted display, there is no perceived parallax motion effect. In addition to stereo panoramas there are other known techniques to render stereographic video to head mounted display such as full three dimensional reconstruction of the scene with the help of additional depth data. That kind of rendering techniques may also enable the parallax motion effect, but these techniques may be rather complex to implement and may have other problems such as sensitivity to depth data errors.