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290 Are the Androids Dreaming Yet?

is 1900 by 1000 pixels with 32 bits of color depth and 100 frames per second. This is a great deal better – if you enjoy watching sport or nature documentaries, the additional resolution is amazing. This still falls far short of reality. An IMAX theatre gives a wrap-around image of about 10,000 by 7,000 pixels and comes closer to the average resolution of the human eye, estimated at about 30,000 by 20,000 pixels. But the eye cheats. It concentrates the rods and cones in the central portion of the retina. Although IMAX achieves the average pixel density of your eye, it comes nowhere near the peak density which is nearly 10,000 times greater.

For a truly equivalent experience, we would need about 320 million pixels per eye at a frame rate of 120 frames per second, allowing us full stereo synthesis. At this speed and resolution, we are matching the visual acuity of the eye and should be able to fool it completely. But there is one more problem to overcome: The image is not interactive. Move your head in the real world and the image will change. The objects in the foreground will vary their position in relation to the background, so-called motion parallax. Try it now, move your head and you will see that the book, or screen you are reading moves in relation to the background. In a simple digitized 3D image this will not happen. You will have a 3D image but you will not have a real image, a light field.

To create a real image you need to view a hologram or use head-tracking technology. A hologram records the light waves given off by an object in multiple directions rather than just the intensity of the light striking the camera through a single focal point. When you shine a laser back through the hologram, it regenerates the light waves as they would have originally come from the object. That light can be viewed from different directions, giving the impression of three dimensions rather than a mere two-dimensional photograph. There is often a limitation in viewing angle because the original photographic plate must wrap all the way around an object to capture the full 3D light field, but the illusion is very convincing.

A more effective way to create a real experience – and one with no restriction on viewing angle – is to construct the image in a computer and track the movement of your head. The computer can create the two-dimensional images each eye would see if the scene were truly three-dimensional. Computer software resolves motion parallax and a host of other elements, but to do so the computer must understand a model of the world so it can calculate how the scene would look from a particular angle and in the appropriate lighting. Some recent games such as Activision’s ‘Call of Duty’ do this, and the experience is compelling.

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