How 3D??

Posted by Ali Reda | Posted in | Posted on 12/13/2010

There many types of 3D created images but mainly in media (Movies and Games) there is mainly:

Auto-stereoscopy
Is the sole 3D technique among those described that does not require the use of glasses on the part of the viewer. Yet it does require a so-called 'auto-stereoscopic display', where the viewer has to position himself precisely and has to keep this angle in order to see a 3D image similar to holography.

Stereoscopic Vision                                                                                                                 
Two separate images reach the brain simultaneously one per eye and the brain calculates distance of the object from us.Stereoscopy uses this techniques where two images perceived from different perspectives. Each eye of the viewer is provided with separate image information, so that a pair of 2D images using the brain create an image of three-dimensionality and the illusion of depth.



Now We Have a Stream of image pairs, how can we assign left image to left eye only and right image to right eye only?


Liquid crystal shutter glasses : Glasses containing liquid-crystal that block or pass light through in synchronization with the images on the screen usually the rate for each eye is 60 Hz resulting in combined images on screen to alternate with 120 Hz, using the concept of alternate frame sequencing.Nvidia 3D Vision gaming kit introduced in 2008 introduced this technology to mainstream consumers and PC gamers and it is used by most 3D-TVs.

Linearly polarized glasses: Two images are projected superimposed onto the same screen through orthogonal polarization filters.One image horizontal and the other one vertical. The viewer wears low-cost eyeglasses which also contain a pair of orthogonal polarizing filters. As each filter only passes light which is similarly polarized and blocks the orthogonally polarized light, each eye only sees one of the images, and the effect is achieved. Linearly polarized glasses require the viewer to keep his head level, as tilting of the viewing filters will cause the images of the left and right channels to bleed over to the opposite channel. 

 

Circularly polarized glasses: To present a stereoscopic motion picture, two images are projected superimposed onto the same screen through circular polarizing filters of opposite handedness. The viewer wears low-cost eyeglasses which contain a pair of analyzing filters (circular polarizers mounted in reverse) of opposite handedness. Light that is left-circularly polarized is extinguished by the right-handed analyzer, while right-circularly polarized light is extinguished by the left-handed analyzer. The viewer can tilt his or her head and still maintain left/right separation.

 

Infitec glasses: Infitec stands for interference filter technology. The filters divide the visible color spectrum into six narrow bands - two in the red region, two in the green region, and two in the blue region (called R1, R2, G1, G2, B1 and B2 for the purposes of this description). The R1, G1 and B1 bands are used for one eye image, and R2, G2, B2 for the other eye. The human eye is largely insensitive to such fine spectral differences so this technique is able to generate full-color 3D images with only slight colour differences between the two eyes.Sometimes this technique is described as a "super-anaglyph".Dolby uses a form of this technology in its Dolby 3D theatres.

 

Complementary color anaglyphs: Employs one of a pair of complementary color filters for each eye. The most common color filters used are red and cyan. The eye is sensitive to three primary colors, red, green, and blue. The red filter admits only red, while the cyan filter blocks red, passing blue and green (the combination of blue and green is perceived as cyan).The left eye image is then converted to red (blue and green channels set to zero) and the right eye image is converted to cyan (red channel set to zero). These two images are then combined. They can be seen overlapping in the middle of the diagram. When they are fully overlapped the result is the anaglyph .This anaglyph therefore contains the left eye view and the right eye view, but as different colours. When the image is viewed through red green spectacles then the two images can be separated. This is because the left eye only receives the red image and the right eye only the green.

Sony Combined all 3D-Media forms in a single image




A 3D TV, Nvidia 3d Vision, PS3 and programs like MakeMe3D will be able to create a 3D image from a 2D image. They can take a single stream (2D) and it creates separate images for the left and right eye, which - when viewed together - result in 3D adding depth to it like giving games which aren't 3D the 3D feel. But to get the full 3D effect, you need 3D content that was filmed and broadcast specifically for 3D. Both Sony Bravia 3d and Nvidia 3d Vision use the same shutter glass technique.

With any previous technique you need a 120 Hz TV with one of the following notations:
  1. Full 3D or 3DTV : 3D HDTVs are capable of displaying 3D out of the box.
  2.  3D-ready HDTV: You will need to buy an adapter to get your HDTV to display 3D. Without this adapter, your HDTV will display great 2D pictures, but you will not be able to watch anything in 3D.

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