Wednesday 1st October 20081.0 Principles
The third dimension of sight is generated within the brain as it identifies and understands the different views as seen by the left and right eye. The challenge of providing a real 3D view to a consumer lies in the flat 2D nature of monitors and print. The left and right eyes see the same image on a monitor, and thus it is flat and without depth. To convince the brain that there is a third dimension to the scene presented, the left and right eye must be shown different images. Various techniques of ‘trickery’ to achieve this have been developed. One technique is to use a separate display for each eye simultaneous, either using two displays, or interleaving two images via filtration. Another is to flick between showing each view whilst obscuring the ‘other’ eye. What follows is a brief overview of current 3D viewing technology and its practicality for consumer level use.
2.0 Techniques
2.1 VR Headsets
US military using a stereo VR headset driven by a bespoke simulator for parachute training
VR headsets are a bespoke, bulky and expensive means to provide images to the eye. Most headsets provide both eye with the same image, giving the impression of a single flat display some distance from the user. Some, however, offer a separate feed to each display driven by a bespoke workstation to provide an immersive 3D effect. These typically cost upwards of £1000.
2.2 Polarised Glasses
Typical polarized glasses for Imax cinemas
By projected two displays simultaneously, with the wave-length of each display polarized 90 degrees apart – a viewer with matching polarised glasses can establish a 3D view. This is the technique used by Imax 3D cinemas. This technique has now been brought to the consumer level by integrating polarisation into a single LCD display by Zalman who produced a “19 and a “22 display for around £300 and £350 respectively.
2.3 Shuttered Glasses
Wireless IR commanded LCD shutter glasses
Rather than showing two displays simultaneously, the shuttered technique utilised the inherent latency and memory within the brains ability to view, by flicking between a left and right eye view. A CRT monitor (LCD’s are unable to refresh quickly enough) is used at a high refresh rate, typically 120hz. A pair of powered LCD glasses commanded via cable or via an IR transmitter are synchronised to this rate, and alternately render each eye opaque. The display is then commanded to show a left eye view when the right eye is opaque and vice versa, in rapid succession, producing a net frame rate of half that of the monitor (i.e. 60 hz). Wireless glasses are typically priced at £60
2.4 Anaglyph
Card mounted Red-Cyan anaglyph glasses
Anaglyphs use colour filtration to provide each eye with a separate image from an LCD or CRT display, or a printed imaged. The image targeted for the left eye is filtered red, and the right eye filtered green and blue. Anaglyph images are therefore typically greyscale. A varying level of success has been achieved in colour by using the red channel of a left-eye image, and the green and blue channels of the right eye image . The anaglyph technique is often unreliable or ineffective in those who suffer from colour-blindness. The price of glasses is negligible – with card mounted glasses costing as little as 40 pence.
3.0 Content Provision
3.1 VR Headsets
VR headsets typically require bespoke 3D workstations with specific graphics cards driving the twin displays. This technology has not filtered down to the consumer level as of 2008.
3.2 Polarisation/Shuttering
Customised drivers for most nVidia and ATI graphics cards are available to enable most common game engines (including the heavily customisable Half Life 2) to produced a 3D image with the Polarised solution provided by Zalman, or the LCD shuttered glasses. Browser plugins such as Cult 3D (now unsupported) or Viewpoint Media Player are not supported with this technique. There are problems with the reliability of this technique between the plethora of different combinations of motherboard, graphics card, monitor, operating system and graphics drivers. For this to work a ‘PC enthusiast’ level of computer knowledge is required. Most office-based PC’s are not equipped with suitable graphics cards and depend on integrated graphics by Intel which does not support this technology.
3.2 Anaglyph
The same customised drivers provided by nVidia described in 3.2 can also be commanded to provide an Anaglyph view. The same issues regarding compatibility and reliability remain. Drivers from Iz3d (http://iz3d.com) also enable this effect on any Direct 3D display but do cause problems with dual-monitor configurations while enabled. The effect is less convincing and reliable than the others, and again, does not work with browser plugins.
Anaglyph differs, however, in that media can be pre-prepared as stills or animations. These forgo any level of interactivity, however.
Anaglyph still image of 3D model rendered in 3D Studio Max
4.0 Conclusions
4.1 Current technology
The Zalman 3D displays combined with polarized glasses offer the most reliable and trouble-free technique for viewing interactive 3D material. However, material can only be provided using commercial graphics engines and not in-browser plugins such as Viewpoint Media Player.
Anaglyph Glasses can offer a cheap and simple way to gain an element of 3D, but only in non interactive animations or still images can be displayed.
For interactive 3D material, however, a specific platform, and a custom programmed display application need to be developed
4.2 Future technology
It is hard, if not impossible to imagine where this technology may lead. Hollywood has recently begun to revisit the 3D movie industry after a lull during the ’90s. If and how that will feed in to commercially available productions for home viewing remains to be seen, however currently, there is little to suggest that interactivity in 3D will become commercially attractive platform for mass consumption in the next 5 years.