3-D Imaging Systems

3-D Imaging SystemsUnlike two-dimensional images, 3D images create an illusion of depth. The effect of stereoscopy is achieved by presenting different images to the right and the left eye. Due to the work of our brain the two slightly different images created according to certain rules unite into one 3D image. At the meeting of the Royal Society in London, on June 21, 1833, Charles Wheatstone read a lecture about research in stereoscopy. He demonstrated his works using a device based on mirrors. It presented different images to the right and the left eye. This had happened before Daguerre invented photography in 1839. Thus, it's not surprising that stereo photography appeared simultaneously with photography. However, today we will talk about systems that allow creating moving 3D images. The anaglyph method uses glasses with colour filters. It can create 3D images using a regular video channel and a display. The adaptation time is about 30 seconds. After watching, colour perception is disturbed for a corresponding period of time. The other method uses the so called shutter glasses. The right and the left lenses are blocked in turns in the XpanD format. This method is used in some computer games along with video. However, this method requires a very good video card and can't be used with most LCD displays. It needs double the regular scanning speed. The third method employs the so called stereo helmet. The image is shown on two independent mini displays inside. Among the main drawbacks of the budget varieties are the following. There are no in-built head-tracking devices. The screens have small resolutions. Currently the prices for virtual helmets are plummeting. Soon they may become an indispensible part of video games, like a joystick or a mouse. Still, this method is too expensive to be used in movie industry. It is hard to transmit an image to a large number of helmets. Helmets are also expensive. Today, raster 3D technologies are among the most promising. They use space division of the stereoscopic pair and require no glasses. The image on the screen consists of narrow vertical alternating stripes with the images of the stereoscopic pair. A duplex screen with the same spacing is placed in front of the regular screen. Due to the duplex screen each eye sees only certain stripes. If the viewer is sitting far enough from the screen the stripes merge into one half-tone image. There is one big problem with 3D cinema. Looking at a 3D image you naturally expect that it will be possible to look at its different parts. First you can focus on a nearby object then look at an object situated farther away. A 3D image is formed in the same way as in regular flat cinema. However, 3D imposes the focal point on the viewer. The things the director wants to emphasise appear to be sharper. Secondary details are blurred. You can't notice this effect in regular flat cinema. In 3G cinema this interferes with the process of watching. That is why stereoscopy is not yet widely spread. Still, its popularity is growing every year.

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Science & Technology

Tags:

• display
• display information
• PC
• TV