Producing, Storing, and Transmitting 3D Pictures

TDVision makes a camcorder with double optics for 3D recordings.

There are various ways to produce images that have a depth dimension: With two cameras - ideally set apart by the same distance as the human eyes (around 6.5 centimeters) - to record the two perspectives or using a stereoscopic camera with two lenses.

By calculation, using computer animation, primarily with cartoons; since all information here already exists in three dimensions, it's no problem to derive two perspectives.

By generating and inserting a second picture from a real recording; this can either take place in the display itself or using a high-powered computer in a studio. The latter will obviously produce the better results.

There are numerous methods that are used to store three-dimensional images on a storage medium or to broadcast them over a TV channel:

• coloring them in advance, for example, in red-green, red-cyan, or Colorcode;
• using two channels, as separate data, each with full bandwidth;
• putting them in one image, but not combined - for example, as two distorted images beside one another (side-by-side), or as a checkerboard pattern (DLP 3D), or using interlacing;
• using a supplementary data stream that essentially contains just the difference of the second picture from the first;
• storing a 2D image along with a depth signal that gives the spatial allocation of individual objects.

For the colored and in-picture solutions, for example, you can use the existing interfaces, from a normal video connection to HDMI. Otherwise, you'll need double the cables or double the bandwidth (for HDMI). In some processes - the supplementary data stream, for example - one medium will work for both 2D and 3D playback. Checkerboard patterns and side-by-side signals, on the other hand, require special 3D versions. So far, however, standards remain at a rudimental stage.

Texas Instruments developed a transmission process that nests the two images within one another.

With 2D-plus-depth, an additional channel contains spatial information for the objects in the picture.

Sony's proprietary SXRD projection technology cannot achieve the same extremely fast frame rate as the above systems. Thanks to 4k technology (4,096 x 2,160 pixels), however, it's possible here to put the two images one on top of the other on the projection chip, and align them using special optics.

The viewers then use polarized glasses to view the image. With each image therefore having 2,048 x 1,080 pixels, the system can display all 3D movies without having to convert the image. The light output, however, drops significantly as a result of this process.

Imax is the only company that still uses analog projection in a 3D movie theater. Here, they use two projectors and polarizing filters. Imax is in the process of switching over to digital DLP technology; even this still uses two projectors, however, in order to avoid reductions in light output and resolution.