3D TV technology renders an impression of depth while displaying an image over a 2D surface. Yet the human brain knows that a 3D object cannot be contained within a flat surface. This affects our way of seeing 3D content and may even leads to undesirable effects, like disorientation and headaches.
In this article, we discuss these issues to get a better understanding of the problems that may arise. We also see how the difference between human vision and 3D television technology impacts the way film producers shoot content for 3D presentations with the aim of minimizing some of these ill effects.
Introduction to 3D TV Technology
In most simple terms, 3D TV is a display technology that helps you experience TV programs, movies and video games in a stereoscopic effect.
It is based on what is referred to in 3D imaging technology as stereopsis, or separation between two full-size but slightly different images of the same scene―one to be viewed by the left eye and the other by the right eye. This separation is known as parallax, and the amount of parallax in 3D TV content determines the aggressiveness of the 3D experience.
This illusion of 3D however, created by a 3D TV, is created by displaying the 3D content as a two-dimensional flat image!
And here is the source of all problems associated with the present 3D TV technology. The human brain knows that a 3D dimensional object cannot reside over a flat surface! This leads to a number of implications; in the worst case, 3D TV viewing can make you feel sick, while others are literally 3D TV blind.
While 3D TV technology relies on the use of two slightly different images to build up a 3-dimensional representation of the content being displayed on the screen in a similar manner to the way human vision works, yet there are a few distinct differences in the way we see a 3-dimensional object and the way 3D TV technology works.
Active 3D-glasses Systems: Sequential Presentation of Image Content
3D TV technology using active 3D-glasses does not display the two separate images exactly simultaneously in the way we see, but these appear intermixed with one another in what is referred to as field-sequential 3D. This means that each of the two sub-frames with the full-size images intended for the left and the right eyes are displayed intermixed in a sequential order, one after the other rather than simultaneously. The simultaneous representation of the two sub-frames takes place only with passive 3D-glasses systems.
3D display systems using field sequential 3D TV technology make use of active 3D glasses. These separate the two sub-frame images according to the left and right eye to then combine properly in the viewer’s brain; it is the latter that create the illusion of a single 3D image from the way these two 2D images are presented to each eye. Without these glasses, the image on a 3D TV appears as a doubled and blurred 2-D picture of the intended 3D representation.
3D shutter glasses consist of two active LCD lenses―hence the term LCD shutter glasses. These synchronize with the frame content on the screen, to allow each eye see only the content intended for it.
The viewer would not see any flicker as the process is repeated at 120 per second to generate a full 1080p 60 Hz 3D image for each eye.
This means that the system is effectively delivering two simultaneous streams of 1080p60 high definition content even though the source material on the Blu ray disc is in most cases recorded in 24 fps. This is possible thanks to the latest developments not only in 3D HDTVs, but also in HDMI, and a whole new breed of Blu ray players that are capable of supporting the required bandwidth for the two 1080p Full HD streams.
Only HDMI ver. 1.4 (and above) is capable of supporting enough data throughput to deliver two simultaneous streams of 1080p60 over a single HDMI interconnect. And the recently finalized Blu ray standard―designated Blu-ray 3DTM―has been designed to support the new sequential 3D TV in full HD; for this reason, Blu-ray 3D is also referred to as Full HD 3D or FHD3D TV format.
However, not all that glitters is gold. The fact that original movie content has always been recorded in 24fps means that 120Hz refresh rate HDTVs have to use 2:3 pull-down processing to match the 60Hz frame rate of the 3D TV content with that of the 24 fps 3D movie content.