The 3D video is a continuous succession of moving images by applying a particular filter, it allows observing three-dimensional images giving them a sense of depth and producing an effect similar to projecting images on the screen.
There are several types of 3D video:
3D Video based on stereo television
Stereoscopic 3D Video.
3D Video based on auto stereo television
These different types of 3D video correspond to the technology used to create the illusion of depth as well as the necessary technology for viewing.
The process of giving depth to a video and get a false sense of three dimensions has its bases in the double capture of a sequence of images with an angular variation between them. Each sequence of images is intended to be viewed by one eye so that the human brain interprets the two images and reconstruct a third one offering the illusion of depth.
KINDS OF 3D VIDEO
Next, it will be described the different kinds of 3d video, according to the technology required for viewing.
The following summary description of the different types of 3D video technology basis required for viewing.
With this technology the 3D sensation is based in the angular variation of the beam of light from each pixel of the screen. To achieve this change in the beam of light, a small circular and thin membrane composed of silicon nitride, and aluminum coated is used suspended above electrodes.
When it applies a voltage variation over the electrodes that support this membrane is deformed in a parabolic shape and allows changing the wave front of the light beam. This allows switching between the sequences of images for each eye. If, however, the membrane remains flat, the images correspond to video broadcast in two dimensions, so that both video systems are made compatible on the same screen.
ILLUSTRATION 5‑1 SCHEME FOR VIDEO-BASED 3D STEREO TV
As shown in illustration 5-1, each eye interprets a sequence of images, which to the membrane of the pixels of the screen has to deform and project the light beam toward the position of each eye
This system has the advantage of compatibility between the two video formats: Two-dimensional and three dimensional.
On the other side, its main drawback is that only allows a single viewer can view the images simultaneously, and the need to know at every moment the direction in which the viewer looks to produce adequately the variation in the beam produced by the deformation of the membrane.
STEREOSCOPIC 3D VIDEO
The stereoscopic 3D video is an improvement of 3D video system based on stereo televisions.
The stereoscopic video is based on obtaining two different sequences of images for each eye, sequences that should possess a number of similar characteristics and be perfectly synchronized in both shooting and in their projection. There are variations of this type of video that allow the creation of 3D stereoscopic video from a single image sequence that contains the images for each eye.
The 3D video based on auto stereo television is just a stereoscopic video presented on a special display type called WOWvx developed by Philips and is an evolution of the previously explained "3D video based on stereo TV”, because this system is based on principles similar to the deformable membrane of that model to represent three-dimensional images on an LCD screen without special glasses. This will look in more detail in section 3D video issue.
To get the image sequences that enable the production of stereoscopic video there are two possibilities:
Obtain two separate image sequences, one for each eye.
Getting a single image sequence containing a sequence for each eye.
Next, it will be described the first process, including an overview of the means to carry it out. The second process is based on the first one except that to carry out pre-extraction of the two image sequences
Stereoscopic video production from two different image sequences requires at least two imaging systems, usually video cameras.
By the method of multi-camera is allowed to capture video from various perspectives (and are not necessarily two, may comprise a number n of viewing angles).
In this method, n number of video cameras should be placed in an orderly manner in an observation area around the place in which the scene it will be recorded. These cameras must be timed perfectly (either in carrying out the recording or performing a synchronization of video signals later in the production process) and calibrated so as to maintain a common axis that allows the subsequent image overlapping.