Almost real, almost here: A Quick Guide to 3D Displays

Posted at: Thursday 28th August 2008 by Mark Mackay

Long overlooked by gaming, 3D images with depth are back - at Nvision 2008, manufacturers of 3D displays were out in force. We take a look at how depth is the new frontier for graphics.

Techniques for displaying 3D images date back over 100 years, when graphics was a field which had more in common with magic and optical illusions than technology and silicon. While graphics today is altogether more serious, with geometry shaders replacing the kaleidoscope, one area of graphics is still a niche activity: conveying a 3D image that looks three dimensional.

Nvidia has provided limited support for 3D imaging for some time, but with its 3D driver left months between updates and games going unpatched, products such as Zalman's Trimon 3D display have left a lot to be desired. At the recent Nvision 2008 show however it became clear that 3D imaging is far from forgotten. Three different methods of providing depth to a flat image were on show.

THE PASSIVE APPROACH

First up, the ‘passive’ approach, demoed to Custom PC by iZ3D’s Charlie ‘Welder’ Rosenberg. The company was showing a 22in flat panel monitor, featuring a native resolution of 1,680 x 1,050 with a contrast ratio of 700:1 and a 5ms response time. Fairly standard specs, but the display itself actually comprises two LCD panels, each showing what is essentially the same image, but with one being a marginally offset version of the other. Two two displays alternate horizontally orientated rows of pixels to offset the two images. The viewer must wear a pair of polarised 3D glasses, and as a result, the two images are fed to your left and right eyes respectively; when the brain decodes this information, it combines the two images and the difference is used to create the illusion of depth.

This is the same 3D effect Zalman uses in the Trimon, a technique known as stereoscopy - although the Trimon doesn't use two separate LCDs, opting for polarizing filters on the screen itself. As a result of iZ3D's  dual-layer-LCD screen approach, the cost of manufacturing the its display is high: the 22in model retails at $599 and is currently only available to buy from the US, potentially adding to the cost should you be shipping the monitor to the U.K. The 26in prototype model that was on display is yet to be priced.

THE ACTIVE APPROACH

The second method of creating 3D images we saw on at Nvision was the result of a collaborative effort between Viewsonic and Nvidia, which Nvidia is modestly calling 'NVIDIA's GeForce Stereoscopic 3D technology.' As the name suggests, this kit again makes use of stereoscopy, but instead of glasses with a passive polarization filter, the lenses are two LCD screens that alternately block out the view of the left and right eye at a super-fast speed. In order to accommodate this fast switching, Viewsonic has to manufacture a display refresh rate of 120Hz (giving 60Hz per eye). The glasses must by synced to the refresh rate of the monitor and this is accomplished by transmitting data via an infrared box that sits on the chassis of the display. The Viewsonic models available on release of Nvidias technology will be of considerably higher spec than that of iZ3Ds, providing a 1000:1 contrast ratio and a 3ms response time. Nvidia were very tight lipped about the cost of this technology, but seemed very confident that it would be hitting the shelves this year. Given the closeness of the release date, it seems likely that their reluctance to provide a cost is because it will be pretty pricey, although the use of active glasses means you don't need a dual-LCD display as you do with iZ3D.